In the coronavirus family, we have so far known seven that could infect humans. Three have caused major epidemics: SARS-CoV 1, MERS, and now SARS-CoV 2, whose crisis does not end. Four more can cause mild colds, and circulate without being concerned. The oldest of these, the NL63 coronavirus, has separated from an animal strain for at least 900 years. Almost a millennium therefore that these viruses infect us.
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But, at the end of June, an American-Australian study published in Current Biology has largely pushed the cursor: an epidemic of coronavirus would have occurred in humans 25,000 to 20,000 years ago, in East Asia.
Watch human adaptation to coronaviruses
Normally, scientists trace viruses by looking at their genetic evolution. In the case of the variants that are of current concern to us, we know, for example, that they diverge from the starting strain identified in Wuhan because they resemble it a little but not quite. This time, the researchers took the problem from the host’s side: if unknown coronaviruses have infected humans in the past, they have had to adapt to these viruses and we should find a trace of this adaptation.
And indeed, researchers have discovered genetic sequences encoding proteins that interact with coronaviruses in people in East Asia. By retracing the trail, these changes would have appeared around 900 generations ago and remain confined to this region. ” These results suggest that coronaviruses or a virus interacting similarly with the human host caused old localized epidemics Write the geneticists and biologists.
Impossible link between genetics and susceptibility to Covid-19
Be careful, these genes code for proteins linked to the attachment of coronaviruses to human cells, but nothing excludes that other viruses which have now disappeared may have used the same docking system. Proteins, and therefore genes, may not be linked to coronaviruses, although the authors are fairly confident.
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These genes are not present in all of the Asian population today. Thus, for lack of cross-genetic studies with health monitoring on SARS-CoV 2 contaminations, it is impossible to say that carriers are better or less well protected against Covid-19. The study also recalls that ” the limitations of this work and the various factors to be taken into account, including socio-economic ones, make it impossible for the moment to assert an increased genetic susceptibility or not to coronaviruses ».