Table 2.

Important findings on the origin of SARS-CoV-2.

S. no	SARS-CoV-2	Findings	Reference
1	Higher sequence identity between SARS-CoV-2 and RaTG13	SARS-CoV-2 from BAL fluid represented 96.2% sequence similarity between SARS-CoV-2 and bat RaTG13. As per the accumulating evidence, bats could be the closest relative. Also, this study further confirms SARS-CoV-2 spike protein utilizes ACE2 receptor to enter the cells.	[40]
2	Pangolin-CoV is identical to SARS-CoV-2 at the whole-genome level	Zhang et al. has reported that Pangolin-CoV exhibited 91.02% similarity to SARS-CoV-2. Where, the S1 spike subunit of Pangolin-CoV is exhibited much more similarity to SARS-CoV-2 than RaTG13. This data suggest that there are five key amino acid residues involved in binding with ACE2 receptors, which are entirely consistent between Pangolin-CoV and SARS-CoV-2. Also, this data further tells that some of the Pangolin-CoV genes depicted higher amino acid sequence identity to SARS-CoV-2 genes than to RaTG13 genes include ORF1b (73.4%/72.8%), ORF7a (96.9%/93.6%), and ORF10 (97.3%/94.6%) as well as the spike protein (97.5%/95.4%).	[41]
3	SARS-CoV-2 might be a recombinant virus, with its genome evolved from Yunnan bat virus–like SARSr-CoVs and its RBD region acquired from pangolin virus-like SARSr-CoVs.	Lau et al. evidences that SARS-CoV-2 genomes exhibited different percentage genome identities such as 96.1% of SARSr-Ra-BatCoV-RaTG13, 87.8% of SARSr-Rp-BatCoV-ZC45, 87.6% of SARSr-Rp-BatCoV-ZXC21, and 85.3% of pangolin-SARSr CoV/P4L/Guangxi/2017. Additionally, these findings suggest that SARS-CoV-2 showed high amino acid sequence identities with that of SARSr-Ra-BatCoV RaTG13, except the receptor RBD region while RBD is closest to that of pangolin-SARSr-CoV/MP789/Guangdong/2019 infers that SARS-CoV-2 might be a recombinant virus.	[45]
4	SARS-CoV-2 was likely constructed via laboratory recombination	James Lyons-Weiler claimed that SARS-CoV-2 having a unique sequence (1378 bp), which is located in the middle of its spike glycoprotein gene that had no similarity with other coronaviruses. Furthermore, this report also claims that this sequence was much similar to that of a common expression vector named pShuttle-SN commonly used in research.	[46]
5	SARS-CoV-2 is not a laboratory origin	Hao et al. opposed the above mentioned James Lyons-Weiler's conclusion and claimed that sequence (1378 bp) from SARS-CoV-2 was also found in other coronavirus and which exists as naturally. The vector system pShuttle-SN was built in year of 2005 as an expression plasmid carrying a fragment sequence of spike gene from SARS-CoV, which caused the similarity match between plasmid and the SARS-CoV-2 spike gene sequence.	[47]
6	SARS-CoV-2 is not a purposefully manipulated virus or laboratory construct.	Andersen et al. claims that SARS-CoV-2 spike protein has six RBD amino acids that are critical for binding to human or human-like ACE2, is different from SARS-CoV, as a reason, the virus might be the most likely the result of natural selection.	[48]