The SARS-CoV-2 high infectivity is due to the functional polybasic furin cleavage site in the S protein. How it was acquired is unknown. There are two challenges to face: (i) an evolutionary model, to fit the origin of the coronavirus; and (ii) a molecular mechanism for the site acquisition. Here we show genomic fingerprints which are specific of Pangolin-CoVs, Bat-SARS-like (CoVZC45, CoVZXC21), bat RatG13 and human SARS-CoV-2 coronaviruses. This, along with phylogenetic analysis, we found that these species have the same evolutionary origin in the bat, including a genetic recombination of S gene between Pangolin-CoV (2017) and RatG13 ancestors. However, this does not explain why SARS-CoV-2 is the only of them with the furin site, which consists in four amino acid (PRRA) motif. The Arginine doublet is encoded by CGGCGG codons. Surprisingly, none of the Arginine doublet of other furin site of viral proteins from several type of viruses, are encoded by the CGGCGG codons. This makes it difficult to consider a virus recombination as mechanism for the PRRA acquisition. The origin of SARS-CoV-2, is the origin of the recognition cleavage site. The bat coronavirus RaTG13 appears to be the closest relative of the SARS-CoV-2, but was isolated in 2013. So, new RatG13 samples would provide insights into the acquisition of the polybasic motif.

The origin of SARS-CoV-2 is debated, even after 18 months into the COVID-19 pandemic and a special investigation conducted by the World Health Organization. The RaTG13 sequence has been a highlight of discussions surrounding the origin of SARS-CoV-2. Here we express our opinion about the need for better reporting standards for information about sequencing data, especially for pathogens, citing our findings with the reported RaTG13 genome.

RaTG13 (a bat derived SARS-like CoV) is the closest relative sequence of SARS-CoV-2 reported till date. The sample from which RaTG13 was sequenced was a bat fecal swab collected in 2013 from Tongguan, Mojiang, Yunnan province, China. The Illumina based sequence of RaTG13, MN996532.1, was deposited on 27^th Jan 2020 and the raw data (Illumina), https://www.ncbi.nlm.nih.gov/sra/SRX7724752[accn]. There are discrepancies in dates about when the metagenome sequencing of RaTG13 sample was done (2018 or 2020), both stated by the same corresponding author. Comparison of the RNA Seq data of RaTG13 fecal swab to the corresponding data from the bat fecal swabs deposited by the same working group using the same methods indicated that the RaTG13 raw data seemed to be different in various aspects. The fecal swab sample showed abnormally less read of bacterial reads in the swab was exceptionally low, i.e. 0.7%, compared to the 20-90% abundance in other fecal swabs from bats processed by similar methods. Also, another raw data in the form of amplicon sequences was deposited in May 2020; however, the dates mentioned on the files of the sequenced amplicons were older (2017, 2018). The genome assembly of RaTG13 could not be done de-novo and the average coverage of the genome ~8%. Also, literature indicates that RaTG13 RBD cannot bind to Rhinolophus ACE-2 receptors. Collectively, the anomalies in the raw data of RaTG13 and other issues pose an important question about the overall authenticity of the RaTG13 genome sequence.

Genomic analysis indicates that SARS-CoV-2 is most related to RaTG13, a beta corona virus derived from bats by 96% ¹. At present, RaTG13 is only available on the public database in the form of a genome sequence. The genome of RaTG13 (MN996532.1) was sequenced from the RNA of a bat faecal swab collected in 2013 from Yunnan, China, however the exact location is not mentioned. Since RaTG13 is one of the main supports for SARS-CoV-2 to have a natural origin, it is of utmost importance to understand the sample location. RNA dependent RNA polymerase (RdRp) sequence of RaTG13 shows that it is 100% similar to that of bat corona virus BtCoV/4991 and 98.7-98.9% similar to SARS-CoV-2 RdRp ². BtCoV/4991 was described to be a SARS-like (SL-) corona virus from bat faeces sampled in an abandoned mine from Mojiang ². Both the publications ^1,2 are authored by Dr. Zheng-li Shi (Z-L Shi), who is described as the bat woman of China ³. However, BtCoV/4991 has not been mentioned by Zhou et al 2020 ¹ where novel corona virus was first described. Based on the RdRp sequence similarities, similarities in sample collection dates, sample locations, and the fact that RaTG13 is mentioned synonymous to BtCoV/4991 on the Chinese bat database, it is predicted that RaTG13 and BtCoV/4991 originate from the same sample. The sample, bat faecal swab was collected in 2013 from an abandoned mineshaft in Mojiang by Dr. Shi and her work group. In 2012, in a Mojiang mineshaft, six mine workers suffered from atypical pneumonia and three of them died. These workers were engaged in the work of clearing debris from a mineshaft which had a lot of bats and bat faeces ^3,4. A detailed health investigation indicated that the miners suffered from atypical pneumonia mostly of the viral origin ⁴. Therefore, in the light of the present Covid-19 caused by SARS-CoV-2, the fact that its phylogenetic neighbour RaTG13 originated from bat faeces collected from a mineshaft, which was also the origin of pneumonia-like disease in miners in 2012, should be noted.

A recent manuscript (Zhou, P. et al. “A pneumonia outbreak associated with a new coronavirus of probable bat origin”, Nature 579, 270–273 (2020). https://doi.org/10.1038/s41586-020-2012-7) from Wuhan Institute of Virology claimed the identification of a bat coronavirus, RaTG13, which showed 96.2% genome homology with SARS-CoV-2. In this paper, we raise the puzzling observations surrounding the identification, characterization, unique genome features of this RaTG13 strain, as well as its 100% nucleotide identity in partial RdRp gene with another bat coronavirus strain BtCoV/4991. And the paper presented premature hypothesis of potential bat origin of SARS-CoV-2 while RaTG13 strain was not successfully isolated. We also present the concerns on the methodology, data quality and experiment procedures described in this paper. We call for the authors to provide additional data, to share related samples to be verified and further characterized by other scientists.