Discovered 13 "zombie" viruses that had been trapped for millennia in the permafrost of Siberia : the oldest dates back to almost 50,000 years ago and, like the others, has shown that it is still able to infect the cells with which it was put into laboratory contact.

This is demonstrated by the experiments conducted by an international team led by microbiologist Jean-Marie Alempic, of the French National Center for Scientific Research (Cnrs).

The results therefore clarify how the melting of ice due to global warming could awaken unknown and potentially dangerous microorganisms .

The viruses re-emerged from Siberia have a different genome than other currently known viruses. Nine of them would be tens of thousands of years old: the oldest is a giant virus that infects single-celled organisms known as amoebas and has been called Pandoravirus yedoma. The researchers found it buried under a lake, while the other viruses were extracted from other sources, including the fur of a mammoth and the intestines of a Siberian wolf, all buried under the permafrost. Brought to the laboratory and brought into contact with amoebas, the viruses proved to still be capable of infecting them.

The scholars therefore conclude that it is "legitimate to reflect on the risk that ancient viral particles remain infectious and return to circulation due to the melting of ancient layers of permafrost".


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