48,500-year-old virus from Siberian permafrost revived – New Scientist

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Seven viruses from the Siberian permafrost have been revived and multiplied in the laboratory. Among them is the oldest ‘reanimated’ virus to date.

Seven types of viruses that have been frozen for thousands of years in the Siberian permafrost have been brought back to life. The youngest were frozen for 27,000 years, while the oldest was in the ice for 48,500 years. This makes the latter the oldest virus that has been revived so far.

“48,500 years is a world record,” says microbiologist Jean-Michel Claverie of the University of Aix-Marseille in France, who carried out the work with his colleagues. His team has previously revived two 30,000-year-old permafrost viruses. The first virus was announced in 2014.

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The fact that all nine viruses remained able to infect cells shows that ancient viruses from melting permafrost pose a threat to the health of plants and animals, including ourselves.

250 million years old

While 48,500 years may be a record for a virus, several groups claim to have resurrected bacteria that were trapped in sediments, ice or salt crystals for up to 250 million years. However, it remains unclear whether the organisms were really that old. It could also have been much younger organisms that contaminated the samples.

The nine viruses Claverie’s team revived are different from any previously known virus, he says. It is therefore unlikely that they are due to contamination of the sample by modern variants. The team disregarded several other viruses that were allegedly revived because their genomes were too similar to those of known viruses.

According to Claverie, it is quite possible to revive viruses that are much older. The deepest permafrost is up to a million years old. However, it is difficult to determine the age of ancient permafrost because standard radiocarbon dating does not work for samples older than 50,000 years.

Pandoravirus

The 48,500-year-old virus emerged from the permafrost 16 meters below the bottom of a lake in Yuketchi Alas in Yakutia, Russia. It’s a pandora virus; a giant virus that infects single-celled organisms known as amoebas. All nine viruses the team has recovered so far are giant viruses that infect amoebas, because that’s the only thing the team is looking for.

The researchers add permafrost samples to amoebic cultures. They then inspect them under a microscope for signs of infection. This shows that the virus is ‘alive’ and multiplying.

If ancient giant viruses remain contagious after such a long freeze, so will other species, Claverie said. Molecular virologist Eric Delwart of the University of California San Francisco, who has reproduced plant viruses from ancient frozen caribou droppings, agrees. “If the authors do indeed isolate living viruses from ancient permafrost, it is likely that smaller, simpler mammalian viruses can also survive frozen for very long periods of time.”

Risk of contamination

That means there’s a risk that these ancient viruses could infect plants or animals, including humans, if they thaw, Claverie says. According to him, this risk is increased by the melting of the permafrost due to climate change. ‘Bacteria and viruses emerge from that every day.’

While few people in the Arctic used to be exposed to such threats of infection, Claverie says, more and more people are moving there to mine resources such as gold and diamonds. And the first step in mining is to remove the top layers of permafrost. “There is a real danger,” he says. “But it’s impossible to quantify this risk.”

Delwart thinks the risk of an ancient permafrost virus causing a pandemic is much lower than that of viruses circulating in domestic and wild animals. “Global warming is terrifying enough without adding the release of deadly frozen viruses to the long list of expected environmental catastrophes,” he says.

Real threat

But epidemic expert Rebecca Katz of Georgetown University in Washington DC says we should take this danger seriously. “It makes sense to understand all the possible routes for these viruses to emerge so that we are as prepared as possible,” she says. “The threat of ancient viruses released by the thawing permafrost is very real.”

Deliberate attempts to revive permafrost viruses could also be risky, Claverie says. His approach is safe because amoeba-infecting viruses cannot infect plants or animals, he adds. However, a team from the State Research Center of Virology and Biotechnology VECTOR in Russia plans to revive viruses that infect mammoths, Claverie says. ‘That’s horrible. I’m totally against that.’

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