A new study provides evidence that the virus causing Covid-19 is of natural origin and not the result of human manipulation in the laboratory, as some rumors suggest.
“There is immense evidence” that the new coronavirus started from a Chinese laboratory, assured the head of American diplomacy Mike Pompeo on May 3. However, while more and more rumors going in this direction circulate, they are unfounded, assure Chinese researchers. “In particular, one particular feature was highlighted — an insertion ofamino acids — which could be an indication of human manipulation. But our work shows very clearly that this type of insertion can occur in nature,” justifies Weifeng Shi, professor at the Institute of Agent Biology pathogens from Shandong First Medical University (China) in an article published on May 10 in the journal Current Biology.
“Since the discovery of SARS-CoV-2, a number of unfounded suggestions have been made that the virus originated in a laboratory (…) In particular, it has been proposed that the insertion of S1/S2 is very unusual and possibly indicative of laboratory manipulation. Our article shows very clearly that these events occur naturally in wild animals. This provides strong evidence that SARS-CoV-2 is not a lab escape,” assures Weifeng Shi, lead author of the study.
Genome-wide, the closest relative of SARS-CoV-2 is another virus, called RaTG13, identified in bats in Yunnan province. However, by analyzing 227 bat samples, also taken from Yunnan, between May and October 2019, they identified another virus quite similar to the one causing Covid-19: RmYN02.
Events that can occur “naturally in animal betacoronaviruses”
“Since the discovery that bats are the reservoir of the SARS coronavirus in 2005, there has been a great deal of interest in bats as reservoir species for infectious diseases, in particular because they carry a very large diversity of RNA viruses, including coronaviruses”, explains Professor Shi.
While RmYN02 cannot infect human cells, it is very closely related to SARS-CoV-2 in parts of the genome. In the longest coding section of the genome, 1ab, they even share 97.2% of their RNA. Moreover, RmYN02 has amino acid insertions close to those seen on SARS-CoV-2 and which were rumored to be evidence of manipulation of the virus in a laboratory. Also, the fact that these insertions are similar but not identical to those of SARS-CoV-2 shows that they occurred during independent insertion events and that it can happen naturally.. “Our results suggest that these insertion events that initially seemed very unusual may, in fact, occur naturally in animal betacoronaviruses,” explains Professor Shi.
“Our work sheds further light on the evolutionary ancestry of SARS-CoV-2. Neither RaTG13 nor RmYN02 are direct ancestors of SARS-CoV-2, as there is still an evolutionary gap between these viruses. But our study strongly suggests that sampling more wild species will reveal viruses that are even more closely related to SARS-CoV-2 and possibly even its direct ancestors, which will tell us a lot. on how this virus appeared in humans.”
The suspicious United States
Not sure, however, that this new study is enough to overcome the various conspiracy theories that have emerged since the appearance of the Covid epidemic. “China is notorious for its propensity to infect the world and to use substandard labs. This is not the first time that the world has been endangered by viruses from Chinese laboratories”, recently accused Mike Pompeo, refusing to specify whether he thought that the virus had been intentionally released by the Chinese authorities. These last “continue to prevent access to Westerners, to the best doctors. We need to be able to go there. We still don’t have the samples of the virus we need.” he denounced.
Earlier, however, US intelligence said it was joining “the broad consensus of the scientific community to agree that the Covid-19 virus was not man-made or genetically modified” while not ruling out that the pandemic was caused by an accident at the Wuhan Institute of Virology, known for studying coronaviruses. “The intelligence community will continue to rigorously study information and intelligence that emerges to determine whether the outbreak began through contact with infected animals or was the result of a laboratory accident in Wuhan.”the statement concluded.
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