Researchers Revive "Zombie Virus" That's Been Dormant for 50,000 Years

By Russ Burlingame

Researchers in the Arctic have been recovering and studying viruses locked in the permafrost for centuries, in the hopes that they can head off any negative impacts to animal and human health, an the oldest has been dormant for almost 50,000 years. The "zombie" virus, found in the upper layer of the Arctic permafrost, has been frozen for an estimated 48,500 years, but warmer temperatures in the Arctic are starting to melt the permafrost, increasing the risk that these long-frozen viruses could become infectious. Jean-Michel Claverie, an Emeritus professor of medicine and genomics at the Aix-Marseille University School of Medicine in Marseille, France, is studying earth samples from Siberia to see what he can find.

As CNN reports, The Arctic permafrost has a preservative effect on things frozen in it, because besides just being cold, it's also removed from sunlight, and there's very little oxygen present. Those factors all unite to preserve everything from animals to plants to viruses that might decay in other circumstances.

"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, California.

Claverie's work aims to find whatever viral strains still exist within the permafrost, and test whether they still have the potential to be infectious. Such "zombie viruses" -- so called because they appeared dead but can reanimate under the right circumstances, not because of any potential illnesses they would cause -- are rare, but Claverie has found some.

Claverie studies "giant viruses," which are large enough to be seen under a regular light microscope, rather than an electron microscope. He is also only experimenting with viruses that he thinks will target single-celled organisms, rather than anything that could prove infectious to animals or humans.

In 2014, Claverie successfully revived a virus that was 30,000 years old by inserting it into cultured cells. The next year, he isolated a different virus type, and has apparently done it several more times since then, according to a new paper in the journal Viruses.

Claverie writes of five new virus families -- the youngest, which came from the stomach contents and coat of a woolly mammoth, was 27,000 years old, while the oldest, which was dug out of an underground lake 52 feet below the surface of the permafrost, is dated back to 48,500 years ago.

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