‘Zombie virus’ resurrected after being frozen for 48,500 years

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Thawing of frozen landscapes has the potentional to unleash infectious “zombie viruses” that have been locked underground for thousands of years, according to new research.

One quarter of the Northern hemisphere has permanently frozen ground beneath it, and is facing irreversible thawing due to the climate crisis. This decomposing landscape releases carbon dioxide and methane into the atmosphere, adding more heat to the planet.

The new study, led by microbiologist Jean-Marie Alempic from the French National Centre for Scientific Research, looked at samples collected from permafrost in the Russian province of Siberia. From these, scientists were able to awaken 13 new viruses which they labelled “zombie viruses” - including one which remained infectious after more than 48,500 years in deep permafrost.

The study, which is yet to be peer-reviewed, noted that there has been limited research into “live” viruses found in permafrost.

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

The viruses examined in the study were capable of infecting Acanthamoeba - a microscopic, single-celled living organism.

The use of Acanthamoeba as “virus bait” was a valid choice, the researchers said, because they are not only “ubiquitous” in soils and fresh and marine waters but also in pools, taps, drains, aquariums, sewage, as well as in hydrotherapy baths, cooling systems, ventilators, and intensive care units - to name a few.

“The detection of their virus may thus provide a useful test for the presence of any other live viruses in a given setting,” the study said.

While the biohazard risk of reviving prehistorical amoeba-infecting viruses is “totally negligible”, the team noted, the findings suggested that a virus freed from the permafrost could pose future risk to animal or human population -particularly with unexpected, rapid changes caused by the climate crisis.

“It is thus likely that ancient permafrost (eventually much older than 50,000 years, our limit solely dictated by the validity range of radiocarbon dating) will release these unknown viruses upon thawing,” it read. “How long these viruses could remain infectious once exposed to outdoor conditions (UV light, oxygen, heat), and how likely they will be to encounter and infect a suitable host in the interval, is yet impossible to estimate. But the risk is bound to increase in the context of global warming when permafrost thawing will keep accelerating, and more people will be populating the Arctic in the wake of industrial ventures.”