“Zombie” viruses melt in melting permafrost.  But don't panic - for now

“Zombie” viruses melt in melting permafrost. But don’t panic – for now


Permafrost thaw due to climate change could expose a vast store of ancient viruses, according to a team of European researchers, who claim to have found 13 previously unknown pathogens that had been trapped in the previously frozen ground of Russia’s vast Siberian region.

The scientists found a virus which they believe washed up under a lake more than 48,500 years ago, they said, pointing out a potential new danger from a warming planet: what they called zombie viruses.

The same team of French, Russian and German researchers had previously isolated ancient permafrost viruses and published their findings in 2015. This The concentration of fresh virus suggests these pathogens are likely more common in the tundra than previously thought, they suggest in a preprint study they published last month on the BioRxiv website, a portal where many scientists disseminate their research before it is accepted in a scientific journal.

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

Although the ones they studied were only infectious to amoebae, the researchers 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 the specter of future pandemics was raging among the ranks of the Siberian steppe weak on the list of current public health threats. Most new — or old — viruses aren’t dangerous, and those that survive in the freezer for thousands of years tend not to fall into the category of coronaviruses and other highly infectious viruses that lead to pandemics. they stated.

The conclusions of the European team have not yet peer reviewed. But independent virologists have declared that their the conclusions seemed plausible and were based on the same techniques that have produced other verified results.

The risks from pent-up viruses in the Arctic are worth watching, several scientists have said. Smallpox, for example, has a genetic structure that can withstand long-term freezing, and if people come across the thawed corpses of smallpox victims, there is a chance that they will become infected again. Other classes of viruses – like the coronaviruses that cause covid-19 – are more fragile and less likely to survive in the freezer.

“In nature, we have a big natural freezer, which is Siberian permafrost,” said Paulo Verardi, a virologist who heads the University of Connecticut’s Department of Pathobiology and Veterinary Sciences. “And that can be a little worrying,” especially if the pathogens are frozen inside animals or people, he said.

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

For the most recent research, the European team took samples from several sites in Siberia over a series of years from 2015. The viruses they found – of an unusually large type that infects amoebas – 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 targeting the amoeba was found in the frozen intestinal remains of a Siberian wolf from at least 27,000 years ago, the l ‘crew.

The researchers used amoebae as “virus bait”, they said, because they thought it would be a good way to search for viruses without spreading ones that could spread to animals or humans. But they said that didn’t mean those 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, around four times the global average. For many recent summers it has been plagued by wildfires and temperatures reaching 100 degrees Fahrenheit. And its permafrost – ground so cold it stays frozen even all summer – thaws quickly. This means that organisms that have been locked away for thousands of years are now exposed, as longer periods of defrosting at the ground surface allow objects that had been trapped below to rise to the top.

Researchers say the risk of humans stumbling upon human or animal carcasses is increasing, especially in Russia, whose far north is more densely populated than arctic regions in other countries. The team gathered some of their samples in Yakutsk, a regional capital and one of the fastest growing Russian cities due to a mining boom.

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

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

New microbes are emerging or reappearing all the time, Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, told The Washington Post in 2015, when researchers first discovered permafrost.

“It’s a fact of our planet and our existence,” he said. “The discovery of new viruses in permafrost is not much different from all of this. Its relevance will depend on an unlikely sequence of events: The permafrost virus must be able to infect humans, then it must [cause disease], and it must be able to spread effectively from human to human. It can happen, but it is very unlikely. »

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

An extinct virus “appears to be a low risk compared to the large number of viruses that circulate among vertebrates around the world, and which have proven to be real threats in the past, and where similar events could occur in the future. future, as we still do today, lack the framework to recognize them in advance,” said Colin Parrish, a virologist at Cornell University who is also president of the American Society for Virology.

Francis reported from London.

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