Origin of the Covid: the hope of a “major breakthrough” after a discovery by the Institut Pasteur

It could be a “major breakthrough” in the search for the origins of Covid-19. Viruses close to SARS-CoV-2, capable of infecting humans, have been found in northern Laos in bats, according to the conclusions of work by researchers at the Institut Pasteur, in open access since Wednesday on the “Research Square” scientific platform.

These conclusions are the result of a field mission carried out in late 2020 and early 2021 in the north of the country with different species of bats living in limestone caves, in order to better understand the evolution of SARS-CoV-2 and its origins, which have been the subject of intense speculation for months.

The samples took place in a region that is part of an immense karstic relief, geological formations mainly made up of limestone, which also encompasses northern Vietnam and southern China. “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.

“Laos shares this common territory with southern China, filled with cavities where bats live, hence the idea of ​​going there”, continues Marc Eloit. Because what happens there is representative of this ecosystem. Gold, “For various reasons which accumulate, it is suspected that certain insectivorous bats could be the reservoir of the virus”.

In detail, the virus sequences found in bats are almost identical to those of SARS-CoV-2 and researchers have been able to demonstrate their ability to allow viruses to enter human cells. However, the viruses studied lacked the “furin site” present in SARS-CoV-2, a function which activates the so-called Spike protein by allowing the virus to better enter human cells and whose existence conditions the pathogenicity of the virus.

Several hypotheses could explain this missing link, argues 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 furin 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, 2000 km away? No answer for the moment. Be that as it may, Mr. Eloit qualifies this study as“major advance in the identification of the origin of SARS-CoV-2”, whose main conclusion would be that there are viruses very similar to SARS-CoV-2 in bats capable of infecting humans without an intermediate animal, such as the pangolin.

At the end of August, WHO experts, author of a report on the origin of the Covid, warned that the research was “to the point of death” on this topic. Without providing a clear answer, this report listed four more or less probable scenarios, the most likely then being that of the transmission of the virus to humans via an animal infected by a bat.