The coronavirus could have several animal origins: study

SARS-CoV-2, the virus that causes Covid-19, could have been transmitted multiple times from animals to humans, according to a preliminary analysis of viral genomes sampled from people infected in China and elsewhere at the start of the pandemic.

The results, published on the virological.org discussion forum and not yet peer reviewed, may challenge the hypothesis that SARS-COV-2 escaped from a laboratory, Nature reported.

The discovery could be the “dagger to the heart” of the hypothesis that SARS-CoV-2 escaped from a lab, rather than coming from the wildlife trade, said Robert Garry, a virologist at the ‘Tulane University in Louisiana, United States. .

But others say more research is needed, especially given the limited genomic data from the start of the pandemic.

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The first viral sequences, taken from people infected in late 2019 and early 2020, are divided into two major lineages, called A and B, which have key genetic differences.

The B line has become the dominant line in the world and includes samples taken from people who visited the Huanan seafood market in Wuhan, which also sold wild animals. Lineage A has spread to China and includes samples from people linked to other markets in Wuhan.

“This is a very important study. If you can show that A and B are two separate lineages and there have been two fallouts, that virtually eliminates the idea that it came from a lab,” Garry said.

The results are “consistent with the fact that there have been at least two introductions of SARS-CoV-2 into the human population,” added David Robertson, a virologist at the British University of Glasgow.

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The team analyzed 1,716 genomes of SARS-CoV-2 in the open database called GISAID that were collected before February 28, 2020, and identified 38 of these “intermediate” genomes.

But when they took a closer look at the sequences, they found that many of them also contained mutations in other regions of their genomes. And they say these mutations are definitely associated with lineage A or lineage B – which discredits the idea that the corresponding viral genomes date from an intermediate stage of evolution between the two lineages, the team said.

The team suggests that a lab or computer error probably occurred while sequencing one of the two mutations in these “intermediate” genomes.

However, the team countered that even though some of the genomes were sequenced correctly, other parts of the same genomes, or the locations from which the samples were collected, still make it clear that they belong to one or the other. other line.

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