Origin of Covid-19: viruses close to SARS-CoV-2 discovered in bats

the essential It could be a “major advance” in the search for the origins of the Covid – 19: researchers from the Institut Pasteur have identified viruses similar to SARS-CoV? 2 in bats in northern Laos, capable of infecting humans.

The conclusions of the work, which has been freely available since Wednesday on the scientific platform “Research Square”, have yet to be peer reviewed for publication in a scientific journal.

In order to better understand the evolution of SARS-CoV-2 and its origins, which have been the subject of intense speculation for months, researchers from the Institut Pasteur in Paris, the Institut Pasteur in Laos and the National University of Laos led end 2020 and start 2021 a field mission in the north of the country with different species of bats living in limestone caves.

“The original idea was to try to identify the origin of this epidemic”, explains to AFP Marc Eloit, head of the laboratory ” discovery of pathogens “at the Institut Pasteur in Paris, whose teams analyzed the various samples collected. “For various reasons which accumulate, it is suspected that certain insectivorous bats could be the reservoir of the virus”.

The samples took place in an area forming part of an immense karstic relief, geological formations mainly made up of limestone, which also encompasses northern Vietnam and southern China.

“Laos shares this common territory with southern China, filled with cavities where bats live, hence the idea of ​​going over there “, continues Marc Eloit. Because what happens there is representative of this ecosystem.

Conclusions of analyzes by the Institut Pasteur: the virus sequences found in bats are almost identical to those of SARS-CoV-2 and researchers were able to demonstrate their ability to allow viruses to enter human cells.

However, the viruses studied lacked the “furin site” present in the SARS-CoV-2, a function that activates the so-called Spike protein by allowing the virus to better enter human cells and whose existence conditions the pathogenicity of the virus.

No intermediary?

Several hypotheses could explain this missing link, advances Marc Eloit. “Perhaps a non-pathogenic virus first circulated in humans before mutating,” he emphasizes, for example. “Or a virus very close to the identified viruses has this furinous site, but we have not yet found it”.

Another question: “how did the bat virus found in caves get to Wuhan”, in China, the known starting point of the pandemic, 2 km away? No answer for the moment.

Anyway, this study “is a major advance in the identification of the origin of SARS-CoV -2 “, estimates Mr. Eloit.

The main conclusion of which would be that there are viruses very close to SARS-CoV-2 in bats capable of infecting humans without an intermediate animal, such as the pangolin.

At the end of August, the WHO experts, author of a report on the origin of the Covid, warned that research was “at a standstill” on this subject.

They were part of a team of 17 international experts mandated by WHO and 17 Chinese experts, whose report was released on 19 March, after an investigation in January in Wuhan.

Without providing a clear answer, this report listed four more or less probable scenarios. The one considered most likely was transmission of the virus to humans via an animal infected with a bat.

Next came the hypotheses of direct transmission without an intermediate animal, of transmission through food, in particular frozen meat, and finally of an accidental laboratory leak, however deemed “extremely improbable”.

Since then, “no data” supporting “the hypothesis of a laboratory leak has been neither published nor submitted to the WHO”, noted the experts.

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