Scientists revive ‘zombie’ virus trapped for 48,500 years in Arctic permafrost

‘Zombie’ viruses that have spent up to 48,500 years frozen in the ground could reawaken as permafrost melts due to climate change, scientists warn.

Significantly warmer temperatures in the Arctic are already melting the region’s permafrost, the permanently frozen layer beneath the Earth’s surface.

Researchers are now trying to assess how much of a risk the bacteria and viruses trapped inside could pose to humans – and they’re carefully reviving some in the process.

“Fortunately, we can reasonably hope that an epidemic caused by a revived prehistoric pathogenic bacterium can be quickly controlled by the modern antibiotics at our disposal (…) even if bacteria carrying antibiotic resistance genes seem to be surprisingly widespread in permafrost”, authors of a study published in February in the magazine Virus writing.

He warned that “the situation would be much more dire in the case of plant, animal or human diseases caused by the resurgence of an old unknown virus” for which there would be no specific treatment or vaccine immediately available.

Permafrost thaw in Siberia has previously been linked to anthrax outbreaks in reindeer, as unusually hot summers have caused ancient anthrax spores to resurface from animal graveyards.

In this latest study, French researcher Jean-Michel Claverie and his team reported that they succeeded in isolating and reviving several ancient permafrost viruses, including a giant virus strain (Pithovirus) found in a permafrost sample 27,000 years old containing a lot of mammoth wool.

Most of the virus isolates belonged to the Pandoraviridae family, a family of double-stranded DNA viruses that infect amoebas – very small, simple organisms consisting of a single cell.

Unknown viruses yet to be discovered

“This study confirms the ability of large DNA viruses infecting Acanthamoeba to remain infectious after more than 48,500 years in deep permafrost,” the authors wrote.

For safety reasons, Claverie and his team focused on reviving prehistoric viruses that target single-celled amoebas, rather than animals or humans.

Other scientists in Russia are currently looking for “paleoviruses” directly from the remains of mammoths, woolly rhinos or prehistoric horses preserved in permafrost.

“Without needing to embark on such a risky project, we believe our results with viruses infecting Acanthamoeba can be extrapolated to many other DNA viruses capable of infecting humans or animals,” Claverie and his team wrote. .

They warned that as yet unknown viruses are likely to be released as the permafrost thaws.

“How long these viruses might remain infectious once exposed to outdoor conditions (UV light, oxygen, heat), and what is the likelihood that they will encounter and infect a suitable host in the meantime, is still impossible to estimate,” they said.

“But the risk is set to increase in the context of global warming, in which the melting of permafrost will continue to accelerate and more and more people will populate the Arctic in the wake of industrial enterprises.”

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