As the world heats up, vast slabs of permafrost are melting, releasing materials that have been trapped in its icy grip for years. This includes a host of microbes that have lain dormant for hundreds of millennia in some cases.
To study emerging microbes, scientists have now resurrected a number of these “zombie viruses” from Siberian permafrost, including one thought to be nearly 50,000 years old – a record age for a frozen virus reverting to a state capable of infecting people. other organizations.
The team behind this work, led by microbiologist Jean-Marie Alempic of the French National Center for Scientific Research, says these resuscitating viruses potentially pose a significant threat to public health, and that further study must be conducted to assess the danger that these infectious agents might pose upon awakening from their freezing slumber.
“A quarter of the northern hemisphere rests on permanently frozen ground, called permafrost,” the researchers write in their paper.
“Due to global warming, the irreversible melting of permafrost releases frozen organic matter for a million years, most of which decays into carbon dioxide and methane, further enhancing the greenhouse effect.”
The 48,500-year-old amoeba virus is actually one of 13 described in a new study now in preprint, with nine thought to be tens of thousands of years old. The researchers established that each was distinct from all other known viruses in terms of genome.
While the record breaking virus was found under a lake, other extraction sites included mammoth wool and the intestines of a Siberian wolf – all buried under permafrost. Using live single-celled amoeba cultures, the team proved that viruses still had the potential to be infectious pathogens.
We are also seeing large numbers of bacteria released into the environment as the world warms, but given the antibiotics available to us, one could argue that they would prove less of a threat. A new virus – like SARS-CoV-2 – could be much more problematic for public health, especially as the Arctic becomes more populated.
“The situation would be much more dire in the case of plant, animal or human diseases caused by the resurgence of an old unknown virus,” write the researchers.
“It is therefore legitimate to wonder about the risk that old viral particles remain infectious and re-circulate through the thawing of old layers of permafrost.”
This team is in shape to diligently dig up viruses in Siberia, with a previous study detailing the discovery of a 30,000-year-old virus. Like the new record holder, it was also a pandoravirus, a giant large enough to be visible under light microscopy.
The revived virus was given the name Yedom from Pandoraviruswhich recognizes its size and the type of permafrost soil in which it was found. Researchers believe there are also many more viruses to be found, beyond those that only target amoebae.
Many of the viruses that will be released when the ice melts will be completely unknown to us – although it remains to be seen how infectious these viruses will be once exposed to light, heat and humidity. oxygen from the external environment. These are all areas that could be the focus of future study.
Virologist Eric Delwart of the University of California, San Francisco, agrees that these giant viruses are just the start when it comes to exploring what lies beneath the permafrost. Although Delwart was not involved in the current study, he has a lot of experience in resuscitating ancient plant viruses.
“If the authors do indeed isolate live viruses from ancient permafrost, it’s likely that even smaller, simpler mammalian viruses would also survive frozen for eons,” Delwart said. new scientist.
The research has not yet been peer reviewed but is available on bioRxiv.
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