Increasingly higher temperatures in Arctic cause permafrost to “thaw”, potentially destructive viruses which, although dormant for millennia, can threaten the health of humans and animals.

While the possibility of a pandemic caused by a disease from the distant past sounds like a far-fetched plot from a science fiction movie, scientists warn that the risk, although low, is underestimated.

Chemical and radioactive waste left over from the Cold War, with the potential to cause serious harm to wildlife and local ecosystems, can also be released during the “thaw” of frozen ground.

“There’s a lot going on in the permafrost that’s worrying, and it really shows why it’s important to keep as much of the permafrost frozen as possible,” said Kimberly Miner, a climate scientist at NASA’s Jet Propulsion Laboratory at the California Institute of Technology. Pasadena, California.

Permafrost, sediments or rocks cover a fifth of the Northern Hemisphere, forming the basis of the arctic tundra and boreal forests of Alaska, Canada and Russia for millennia. It works like one types of chronocapsules which preserves, in addition to ancient viruses, the mummified remains of extinct animals, some of which scientists have been able to find and study.

Permafrost is good storage not only because of the cold. anoxic environment where no light can reach. However, today’s temperatures in the Arctic are rising four times faster than in the rest of the planet, weakening the region’s top layer of permafrost.

To better understand the danger posed by frozen viruses, Jean-Michel Claverie, emeritus professor of medicine and genomics at the Aix-Marseille University School of Medicine in Marseille, examined soil samples collected from Siberian permafrost to see if they contained viral particles. remain infectious. He’s looking for “zombie viruses,” as he calls them, and he actually managed to find some of them.

Virus hunter

Claverie is studying a special type of virus he discovered in 2002. Known as giant viruses, they are much larger than normal viruses and are visible through a conventional microscope rather than a high-powered electron microscope, making them a good model for such laboratory studies.

His efforts to find viruses preserved in permafrost were partly inspired by a group of Russian scientists who, in 2012, brought a wild flower back to life from 30,000-year-old seed tissue found in a squirrel burrow.

In 2014, he managed to revive a virus he and his team had isolated from permafrost by introducing it into cultured cells and making it re-infectious for the first time in 30,000 years. For safety reasons, he decided to study a virus that could only be applied to single-celled amoebae, not animals or humans.

He repeated this scientific feat in 2015 by isolating a different type of virus, again targeting amoebas.

In his last a study published Feb. 18 in the journal VirusesClaveri and colleagues isolated different strains of the ancient virus from several samples collected from seven different permafrost regions in Siberia. can infect cultured amoeba cells.

These latest strains represent five new families of viruses in addition to the two previously recovered. The oldest of them was ca. 48,500 years, obtained from soil radiodating and obtained from a soil sample collected in an underground lake at a depth of 16 meters from the earth’s surface. The newest specimens found in the stomach and wool of a woolly mammoth were 27000 years.

The fact that viruses remain contagious after so many tens of millennia is evidence of one potentially big problem, Claverie warns. He expresses fear that the world will perceive his research as a mere scientific curiosity, not realizing the possibility of the return to life of ancient viruses, which would pose a serious threat to public health.

“We view these amoeba viruses as substitutes for all other possible viruses that might be present in permafrost,” he says.

“We see traces of many, many, many other viruses. So we know it’s there. We don’t know for sure if they are still alive. But our reasoning is that if amoeba viruses are still alive, there is no reason why there shouldn’t be other viruses. alive and able to infect their hostshe adds.

“Not all viruses are bad”

Of course, as the scientists elaborate, they have little to no idea of ​​how long these viruses can remain infectious after exposure to today’s conditions, or how likely they are to meet the right host.

Not all viruses are pathogens that can cause disease. Some benign, even useful for their owners. And despite the fact that about 3.6 million people live in the Arctic, it remains sparsely populated, so the risk of human infection with ancient viruses is extremely low.

However, “the risk will undoubtedly increase in the context of global warming, so permafrost melt will continue to accelerate, and thus more and more people will settle in the Arctic for industrial purposes,” Claverie warns.

Source: CNN