‘Zombie’ viruses thaw from permafrost in Russia

‘Zombie’ viruses thaw from permafrost in Russia


The thawing of permafrost due to climate change can expose a vast repository of ancient viruses, according to a team of European researchers, who say they have found 13 previously unknown pathogens trapped in the previously frozen soil of Russia’s vast Siberian region.

Scientists found one virus that they estimated was stranded under the lake more than 48,500 years ago, they said, noting potential new danger from a warming planet: what they called “zombie” viruses.

The same team of French, Russian and German researchers previously isolated ancient viruses from permafrost and published their findings in 2015. the concentration of fresh viruses suggests that such pathogens are probably more common in the tundra than previously believed, suggest u pre-print study they published last month on the website BioRxiv, a portal where many scientists publish their research before it is accepted in a scientific journal.

“Every time we look, we will find a virus,” said Jean-Michel Claverie, co-author of the study and professor emeritus of virology at Aix-Marseille Université in France, in a telephone interview. “It’s a done deal. We know that every time we look for viruses, infectious viruses in permafrost, we’re going to find some.”

Although the ones they studied were only infectious to amoebas, the researchers he said there was a risk that other viruses trapped in permafrost for millennia could spread to humans and other animals.

Virologists who were not involved in the research said that the specter of future pandemics is being released from the ranks of the Siberian steppes low on the current list threats to public health. Most new – or old – viruses are not dangerous, and those that survive the deep freeze for thousands of years are usually not in the category of coronaviruses and other highly contagious viruses that lead to pandemics, they said.

The findings of the European team are not yet reviewed. But independent virologists said it was theirs the findings seemed convincing and were relied upon techniques that have produced other, proven results.

The risks of viruses accumulating in the Arctic are worth monitoring, several scientists said. Smallpox, for example, has a genetic makeup that can withstand long-term freezing, and if people come across the thawed corpses of smallpox victims, there is a possibility of re-infection. Other categories of viruses – such as the coronaviruses that cause covid-19 – are more sensitive and less likely to survive deep freezing.

“We have a big natural freezer in nature, which is the Siberian permafrost,” said Paulo Verardi, a virologist who heads the Department of Pathobiology and Veterinary Medicine at the University of Connecticut. “And that can be a bit of a concern,” especially if the pathogens are frozen inside animals or humans, he said.

But, he said, “if you do a risk assessment, it’s very low,” he added. “We have a lot more things to worry about right now.”

For the latest research, the European team took samples from several locations in Siberia over a number of years starting in 2015. The viruses they found — an unusually large type that infects amoeba — were last active thousands, and in some cases, tens of thousands of years ago. Some of the samples were in soil or rivers, although one of the viruses that target amoebas was found in the frozen intestinal remains of a Siberian wolf from at least 27,000 years ago, the team said.

The researchers used amoebas as “virus bait,” they said, because they thought it would be a good way to look for viruses without breeding ones that could spread to animals or humans. But they said that doesn’t mean these viruses did not exist in the frozen tundra.

Radical warming leaves millions on unstable ground

Siberia is warming at one of the fastest rates on Earth, about four times the global average. For many recent summers that hit by wildfires and temperatures reaching 100 degrees Fahrenheit. And its permafrost – ground so cold it stays frozen even in summer – is melting fast. This means that organisms that have been locked away for thousands of years are now exposed, as longer periods of thaw at the ground surface allow objects that were trapped below to rise upwards.

Researchers say the possibility of people coming across human or animal carcasses is increasing, especially in Russia, whose far north is more densely populated than the Arctic regions of other countries. Team they collected some of their samples in Yakutsk, the regional capital and one of the fastest growing cities in Russia due to the mining boom.

Heating permafrost has previously been blamed for outbreaks of infectious diseases. An anthrax outbreak in 2016 hit a remote Siberian village and was linked to a 75-year-old reindeer carcass that emerged from the frozen ground. But anthrax, which is not a virus, is not unique to Siberia and is unlikely to cause a widespread pandemic.

Many virologists say they are more concerned about viruses currently circulating in humans than the risk of unusual ones from the permafrost.

New microbes are constantly emerging or re-emerging, Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, he told the Washington Post in 2015when the first discoveries of permafrost researchers came out.

“This is a fact of our planet and our existence,” he said. “Finding new viruses in permafrost is not much different from all this. Its importance will depend on a sequence of unlikely events: the permafrost virus must be able to infect humans, then it must [cause disease], and must be able to spread efficiently from person to person. It could happen, but it’s very unlikely.”

They are more problematic, say many virologists modern viruses that infect humans and lead to diseases that are sometimes difficult to control, such as Ebola, cholera, dengue and even the common flu. Viruses that cause disease in humans are unlikely to survive the repeated thawing-freezing cycle that occurs at the surface level of permafrost. And the spread of mosquitoes and ticks linked to global warming is more likely to infect humans with pathogens, some experts say.

The extinct virus “appears to be a low risk compared to the large number of viruses circulating among vertebrates around the world, which have proven to be a real threat in the past, and where similar events may occur in the future, because the framework for their advance recognition,” said Colin Parrish, a Cornell University virologist who is also president of the American Society for Virology.

Franjo reported from London.

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