Selon une étude, il existerait des virus très proches de SARS-CoV-2 chez les chauves-souris capables d’infecter l’homme sans animal intermédiaire, comme le pangolin. Photo SAM PANTHAKY / AFP

Maybe ” big breakthrough In search of the origins of Covid-19: Researchers from the Pasteur Institute have identified viruses similar to SARS-CoV-2 in bats in northern Laos, capable of infecting humans.

Conclusions of this work, in open access since Wednesday Research Arena platform, has not yet been reviewed for publication in a scientific journal.

“Some insectivorous bats could be a reservoir of the virus”

For a better understanding The evolution of SARS-CoV-2 And its origins, which have been the subject of intense speculation for months, researchers from the Pasteur Institute in Paris, the Pasteur Institute in Laos and the National University of Laos at the end of 2020 and the beginning of 2021 conducted a field expedition in the north of the country where different species of bats live in limestone caves.

« The original idea was to try to determine the origin of this epidemic ‘ Mark Elliott, head of the laboratory, explains. Detecting pathogens At the Pasteur Institute in Paris, his team analyzed the various samples collected. ” For various reasons that accumulate, it is suspected that some insect-eating bats can be a reservoir of the virus.. »

The samples were taken in an area that is part of a massive karst topography, and geological formations consisting mainly of limestone, which also include northern Vietnam and southern China.

« Laos shares this common area with southern China, which is full of cavities where bats live, hence the idea to go there. ‘, continues Mark Elliott. Because what happens there is a representative of this ecosystem.

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Conclusions of the Pasteur Institute analyzes: The sequence of the virus in bats is almost identical to that of the SARS-CoV-2 virus, and the researchers were able to demonstrate their ability to allow the viruses to enter human cells.

Many questions and hypotheses

However, the viruses studied lacked ” furin . site It is present in SARS-CoV-2, a function that activates the so-called spike protein by allowing the virus to better enter human cells and whose presence limits the pathogenicity of the virus.

Mark Elwett says that several hypotheses could explain this missing link. ” A non-pathogenic virus may have first spread to humans before it mutated “, asserts for example.” Or a virus very close to the one identified has this fizz site, but we haven’t found it yet. »

Another question: ” How did the bat virus found in caves reach Wuhan », in China, the well-known starting point of the epidemic, 2,000 km away? No answer at the moment.

Anyway, this study” It is a major advance in determining the origin of SARS-CoV-2 ‘ thought Mark Elliott. The main conclusion that may be that there are viruses very similar to SARS-CoV-2 in bats that are able to infect humans without an intermediate animal, Like pangolins.

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