Zombie viruses are waking up due to climate change – 10/15/2023 – Science

Spending two weeks camping on the muddy, mosquito-infested banks of Russia’s Kolyma River may not seem like the most glamorous work trip. But it’s a sacrifice that virologist Jean-Michel Claverie was willing to make to uncover the truth about zombie viruses — yet another risk that climate change poses to public health.

Their findings reveal a grim reality of global warming as it thaws ground that has been frozen for millennia. Claverie, 73, has spent more than a decade studying “giant viruses,” including those nearly 50,000 years old found in deep layers of Siberian permafrost.

With the planet already 1.2°C warmer than in pre-industrial times, scientists predict the Arctic could be ice-free in summer by the 2030s. Concerns that the warmer climate will release greenhouse gases trapped, like methane, in the atmosphere as the region’s permafrost thaws have been well documented, but dormant pathogens are a less explored danger.

Last year, Claverie’s team published research showing that they extracted multiple ancient viruses from Siberian permafrost, all of which remained infectious.

“With climate change, we are used to thinking about dangers coming from the south,” Claverie said in an interview in his laboratory at the Luminy campus of Aix-Marseille University in France, referring to the spread of vector-borne diseases from regions warmer tropical.

“Now we realize there may be some danger coming from the north as the permafrost thaws and releases microbes, bacteria and viruses.”

Ways in which this could pose a threat are still emerging. A heatwave in Siberia in the summer of 2016 activated anthrax spores, leading to dozens of infections, killing a child and thousands of reindeer.

In July of this year, a separate team of scientists published findings showing that even multicellular organisms could survive permafrost conditions in an inactive metabolic state, called cryptobiosis. They managed to revive a 46,000-year-old roundworm from Siberian permafrost just by rehydrating it.

“It’s fundamental from the point of view that we can stop life and then restart it,” says Teymuras Kurzchalia, professor emeritus at the Max Planck Institute for Cell Biology and Molecular Genetics, who was involved in the study. “This means that it is innate for some living organisms to somehow slow down or suspend metabolic processes.”

For years, global health agencies and governments have been monitoring unknown infectious diseases against which humans have no immunity or drug therapies. The WHO (World Health Organization) in 2017 added a generic “Disease X” to a shortlist of pathogens considered high priority for research and for which it aims to develop an action plan to prevent or contain an epidemic. Since the Covid-19 pandemic shut down the world for months, efforts have only intensified.

“WHO works with more than 300 scientists to analyze the evidence for all families of viruses and bacteria that can cause epidemics and pandemics, including those that can be released as permafrost thaws,” said WHO spokeswoman Margaret Harris.

Although largely unrelated, Claverie’s research occupies a similar boundary. Tucked away at the base of a rocky cliff on the outskirts of Marseille, France, the shelves in his laboratory complex at first glance have the feel of a curio shop or the home of an eccentric collector.

Plastic bottles of soil samples and glass vials of elusive brown liquids jostle for space, while Claverie’s office displays a woolly rhinoceros vertebra and the remains of a mammoth tusk that his team found on an expedition to Siberia in 2019. Expensive machines and a biosafety room within the complex, on the other hand, indicate that this is far from a frivolous pastime.

Just like her workspace, Claverie’s friendly disposition and ready smile are underscored by an intimidating level and variety of knowledge. Coming from a background in theoretical particle physics, applied computer science, and biochemistry, he had no formal training in virology — something Claverie says was an advantage in his career, coming to the field without preconceptions.

Claverie was born and raised in Paris, but his career took him around the world. His first foray into theoretical biology came in 1979, when he turned down a place in the laboratory of famous MIT (Massachusetts Institute of Technology) biophysicist Alexander Rich and instead chose to travel to San Diego to meet Francis Crick—the award-winning biologist Nobel Prize winner who discovered the molecular structure of DNA.

Strolling through the halls of the Salk Institute for Biological Studies, he bumped into the biologist, who, impressed by Claverie’s enthusiasm and determination, gave him a job recommendation.

“We had lunch together every Wednesday after that,” says Claverie.

It was perhaps this propensity to think outside the box that sparked his fascination with permafrost — layers of land that have remained below freezing for at least two consecutive years. Some Siberian permafrost samples date back up to 650,000 years.

“He began work on permafrost after reading that a flowering plant was revived from a piece of fruit frozen for 30,000 years,” says Chantal Abergel, Claverie’s wife and an experimental biologist who heads the lab’s operations.

“He thought that if something as complex as a flowering plant could be revived, then we could hope to revive viruses from permafrost as well.”

Claverie and Abergel work on an X-ray diffraction device used to determine the three-dimensional structure of viral proteins.

Claverie first showed that “live” viruses can be extracted from Siberian permafrost and successfully revived in 2014. For safety reasons, his research has focused only on viruses capable of infecting amoebas, which are sufficiently distant from the human species to avoid any risk of accidental contamination. But he felt the scale of the public health threat indicated by the results had been underestimated or wrongly considered a rarity.

So in 2019, his team isolated 13 new viruses, including one frozen beneath a lake more than 48,500 years ago, from seven different ancient samples of Siberian permafrost — evidence of their ubiquity.

Publishing the results in a 2022 study, he emphasized that a viral infection from an unknown, ancient pathogen in humans, animals or plants could have potentially “disastrous” effects.

“Going back in time 50,000 years leads us to the disappearance of Neanderthals from the region,” he says. “If Neanderthals died from an unknown viral disease and that virus resurfaced, it could pose a danger to us.”

Permafrost, soil that was once teeming with animal life, offers perfect conditions for preserving organic matter: it is natural, dark, oxygen-free and allows little chemical activity. In Siberia, it can reach up to a kilometer deep — the only place in the world where permafrost goes that deep — and covers around two-thirds of Russian territory. In just one gram it is possible to find thousands of species of dormant microbes, according to an article published in the journal Nature in 2021.

For 400,000 years, the underlying layers of permafrost have been largely stable. So much so that Russian cities have sprung up across Siberia, drilling their foundations deep into the concrete-like frozen ground. But now, with the Arctic warming faster than any other area on the planet, vast methane craters have opened up across the region and entire cities are sinking.

More recently, geopolitics has created new blind spots. Arranging trips to Siberia and collaborating with Russian laboratories was not easy even before Russia invaded Ukraine in February 2022. But communications with former colleagues and collaborators in the country have now all but stopped.

Claverie’s laboratory, like many others in the Western world, is government funded. “We were told not to talk to the Russians anymore,” he says.

The effects of global warming in Siberia pose both risks and rewards for the Russian economy. Thawing permafrost is estimated to be putting around $250 billion worth of infrastructure at risk and is already believed to have contributed to environmental disasters such as the 2020 Norilsk oil spill as the ground becomes unstable.

However, the region also has a wealth of natural resources — coal, natural gas, gold, diamonds and iron ore. Unlike other permafrost-covered regions like Alaska and Greenland, Claverie says Russia has been more active in mining these soils: “They’re digging holes everywhere.”

Some scientists also fear that technology such as Russia’s floating nuclear power plant, the Akademik Lomonosov, could turn previously inaccessible areas along the Siberian coast into mining hubs, as ice-free routes through the Arctic Circle increase accessibility. .

Mining at these great depths, in addition to the active layer that thaws each summer, would increase the possibility of human interaction with a potentially harmful ancient pathogen, says Claverie.

This highlights the dilemma intrinsic to research as well — that hunting the next big threat to humanity may inadvertently propagate the danger. The potential for cross-contamination during sampling expeditions is high. Thus, some are beginning to advocate less proactive and resource-hungry approaches.

“It would be good to establish a specialized way of tracking the Inuit population, for example, to see what kinds of diseases they get,” says Claverie. “And if something is coming from the permafrost, we’ll be able to capture it much more quickly.”

Large organizations are also waking up to this risk. Earlier this month, the United States Agency for International Development abandoned its $125 million project to hunt viruses in Southeast Asia, Africa and Latin America that could potentially infect humans, amid concerns that the research itself could trigger a pandemic.

Meanwhile, Claverie will not return to Siberia, regardless of the outcome of the war. He says he has made it clear that the danger exists and that expeditions to discover more secrets buried in these frozen depths would be madness.

“The older you get, the better you become at philosophy,” he says. “Maybe it’s best to leave these things alone.”