Zombie virus revived after 48,500 years in permafrost

The ancient microbe was still capable of infecting cells, bolstering concerns global warming will lead to lethal pathogens being released.

The virus was trapped in Siberian permafrost for nearly 50,000 years. Picture: iStock.

Scientists have revived a virus that had been trapped in Siberian permafrost for nearly 50,000 years, bolstering concerns that global warming will lead to ancient pathogens being released.

That the microbe was still capable of infecting cells highlights the danger of so-called zombie viruses emerging from thawing soils, researchers said.

Known as a pandoravirus, it infects only single-cell organisms and should pose no threat to humans. It had been trapped beneath a lake bed in Yakutia for 48,500 years, making it the oldest “live” virus to be recovered so far.

In a study Professor Jean-Michel Claverie, of Aix-Marseilles University, and his colleagues say that up to a fifth of the land of the Northern hemisphere is underpinned by permanently frozen ground. This permafrost is thawing, releasing organic matter that has been locked away for up to a million years. Much of it will decompose, producing carbon dioxide and methane, which will reinforce global warming.

The permafrost also contains viruses and other microbes that have remained dormant since prehistoric times. The researchers say that there have been no significant updates on the discovery of “live” viruses in permafrost since 2015.

“This wrongly suggests that such occurrences are rare and that ‘zombie viruses’ are not a public health threat,” they add.

A Russian project is underway to recover “palaeoviruses” directly from the permafrost-preserved remains of mammoths and other extinct animals.

In order to “restore an appreciation closer to reality”, they say that they were able to isolate 13 types of virus from seven ancient Siberian permafrost samples. They only looked for viruses that would infect an amoeba known as acanthamoeba. This was for safety reasons, as these bugs should not be able to infect people. “The biohazard associated with reviving prehistorical amoeba-infecting viruses is … totally negligible,” they write.

By contrast, they say that a Russian project to recover “palaeoviruses” directly from the permafrost-preserved remains of mammoths, woolly rhinoceros and prehistoric horses is risky, as they would infect mammals. That work is being carried out at the Vector laboratory in Novosibirsk.

Concerns of “zombie” pathogens being reawakened from the ice gained traction in 2016 when a child died in an anthrax outbreak in northern Siberia. The case was linked to a heatwave that melted permafrost and exposed an infected reindeer carcass. The disease had not been seen there since 1941.

Researchers at Ohio State University reported last year that they had detected genetic material from 33 viruses in ice samples taken from the Tibetan plateau. They were estimated to be up to 15,000 years old.

The Times