Scientists revive 'zombie virus' frozen under permafrost for 48,500 years

A computer-enhanced microphoto of Pithovirus sibericum that was isolated from a 30,000-year-old sample of permafrost. Credit: Jean-Michel Claverie/IGS/CNRS-AM

Scientists are concerned after a 'zombie virus' that spent 48,500 years frozen in permafrost in Siberia was able to be revived.

French scientist Jean-Michel Claverie tested earth samples taken from permafrost to see whether any viral particles it contained were still infectious.

The Emeritus professor of medicine and genomics at the Aix-Marseille University School of Medicine in Marseille has been in search of what he describes as “zombie viruses” to better understand the risks posed.

In 2014, he managed to revive a virus that he and his team isolated from the permafrost, making it infectious for the first time in 30,000 years by inserting it into cultured cells.

For safety, he’d chosen to study a virus that could only target single-celled amoebas, not animals or humans.

He repeated the feat in 2015, isolating a different virus type that also targeted amoebas.

Jean-Michel Claverie pictured at the Alfred Wegener Institute in Postsdam. Credit: Jean-Michel Claverie/CNN

And in his latest research, published in February in the journal Viruses, Mr Claverie and his team isolated several strains of ancient virus from multiple samples of permafrost taken from seven different places across Siberia.

Those latest strains represent five new families of viruses, on top of the two he had revived previously.

The oldest was almost 48,500 years old, based on radiocarbon dating of the soil, and came from a sample of earth taken from an underground lake 16 meters (52 feet) below the surface.

The youngest samples, found in the stomach contents and coat of a woolly mammoth’s remains, were 27,000 years old.

Mr Claverie told CNN: “We view these amoeba-infecting viruses as surrogates for all other possible viruses that might be in the permafrost.

“We see the traces of many, many, many other viruses.

“So we know they are there (but) we don’t know for sure that they are still alive.

“But our reasoning is that if the amoeba viruses are still alive, there is no reason why the other viruses will not be still alive, and capable of infecting their own hosts.”

Scientists say the world’s permafrost is getting warmer Credit: AP

What is permafrost?

Permafrost covers a fifth of the Northern Hemisphere, having underpinned the Arctic tundra and boreal forests of Alaska, Canada and Russia for millennia.

It can serve as a time capsule, preserving the mummified remains of a number of extinct animals that scientist have been able to unearth and study in recent years - including two cave lion cubs and a woolly rhino.

The reason permafrost is a good storage medium isn’t just because it’s cold, it’s an oxygen-free environment that light doesn’t penetrate.

But current day Arctic temperatures are warming up to four times faster than the rest of the planet, weakening the top layer of permafrost in the region - and leaving scientists fearing what it could expose beneath.

Chemical and radioactive waste that dates back to the Cold War, which has the potential to harm wildlife and disrupt ecosystems, may also be released during thaws.

Scientists have warned that the risks, though low, of melting permafrost are underappreciated.

“There’s a lot going on with the permafrost that is of concern, and (it) really shows why it’s super important that we keep as much of the permafrost frozen as possible,” said Kimberley Miner, a climate scientist at the NASA Jet Propulsion Laboratory at the California Institute of Technology in Pasadena.

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