Over 200 genetic sequences obtained from some of the earliest samples of COVID-19 in China were deleted from an American database within three months, following a request from the same Chinese researchers who had uploaded them in the first place, say multiple reports on the contentious matter.
However, a researcher in Seattle, US, has been able to recover 13 of these samples from Google drive – the analysis of which, with other genetic information available, suggests 'a variety of coronaviruses may have been circulating in Wuhan before the initial outbreaks linked to animal and seafood markets in December 2019,' reports The New York Times.
While the analysis ‘neither strengthens nor denies’ the theory that the virus could have leaked out of the Wuhan institute of Virology in China (popularly knows as the Wuhan lab), it raises questions about why the sequences were deleted in the first place.
Jesse Bloom, the researcher behind the revelation and a virologist at the Fred Hutchinson Cancer Research Center felt that the deletion of sequences could suggest that someone tried to 'obscure their existence'.
His study is yet to be peer reviewed.
What the Sequences Mean
Bloom and his research partner Michael Worobey were looking for information on genetic sequences of the virus published by different researcher groups, when they found a March 2020 study containing a spreadsheet which included data on 241 genetic sequences collected by scientists at Wuhan University.
Study of genetic sequences is important as it offers clues and information that could help scientists in understanding how the SARS-CoV-2 jumped to humans from other species, like bats, for instance. Early sequences can bring us closer to the exact point when the virus started affecting humans.
When Bloom looked up the Sequences on the US Government-owned Read Archive database, where they had been uploaded, he found them missing.
After some more research, he found that each of the genetic sequences were uploaded on as a single Google Cloud. After keying in the names of files, Bloom could recover 13 of the deleted sequences.
After comparing the the 13 sequences with other published early sequences, Bloom noticed mutations in the Wuhan market virus, that were later missing from sequences of samples collected later.
"“Some of the earliest samples come from the Huanan Seafood Wholesale Market in Wuhan, where an outbreak occurred in December 2019. But those market viruses actually have three extra mutations that are missing from SARS-CoV-2 samples collected weeks later. In other words, those later viruses look more like coronaviruses found in bats, supporting the idea that there was some early lineage of the virus that did not pass through the seafood market.”" - The New York Times.
The report says that the deleted sequences also did not have the three mutations from the Wuhan market, suggesting that, 'by the time SARS-CoV-2 reached the market, it had been circulating for awhile in Wuhan or beyond.'
(With inputs from The New York Times)
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