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The viruses have turned up in mammoth wool, Siberian mummies, prehistoric wolves, and the lungs of an Influenza victim buried in Alaska’s permafrost.
And scientists say there’s more to come.
An international team of researchers from institutions in Russia, Germany and France warns that ‘the risk of ancient viral particles remaining infectious’ has been underestimated.
Worse, these scientists now believe that ‘the risk is bound to increase in the context of global warming, in which permafrost thawing will keep accelerating,’ unleashing some diseases that had been trapped in the ice since prehistoric times.
Climate change risks unleashing more long-dead viruses, the researchers say, as ‘permafrost thawing will keep accelerating.’ Above, scientists examine a 14,300-year-old wolf-dog preserved by the Tumat permafrost since pre-historic times. These remains were found in 2015
The team — which includes experts in genomics, microbiology and geoscience, some of whom have been tracking these resurrected ‘zombie’ viruses for nearly a decade — published their findings in the journal Viruses last February.
Below are six long-frozen microbes that scientists have unearthed from the permafrost’s quickly melting fossil record.
In the late 1990s, Swedish pathologist Dr. Johan V. Hultin found a cache of 1918 Influenza virus RNA in the lungs of a woman slain by the virus nearly 80 years prior.
Dr. Hultin had been searching intentionally for Influenza samples that could help medical researchers better understand how to fight future pandemics.
But his discovery was an early indication of just how easily deadly viruses could be preserved in arctic permafrost.
Hultin, in collaboration with the US Armed Forces Institute of Pathology, exhumed the body of a large Inuit woman buried in a mass grave of Influenza victims near a remote village outside the town of Brevig Mission, Alaska.
Thanks to the permafrost, enough RNA from the Influenza virus was so well preserved that the researchers could sequence the entire 1918 strain’s genome.
But the discover was both a victory for medical researchers and dark omen of what other diseases might be frozen in time under the ice.
Thanks to the Alaskan permafrost, enough of RNA from the 1918 Influenza virus was so well preserved that researchers could sequence the entire pandemic strain’s genome. Above, a colorized image of the 1918 Influenza virus taken by a transmission electron microscope
First dredged out of the Siberian permafrost in 2014, from 100 feet (30m) under the ground, the gigantic ancient virus Pithovirus sibericum is one of the few viruses visible under an ordinary, high school-style, light microscope.
At about 1.5 micrometers, P. sibericum is over seven-times the size of a modern human-infecting virus, which typically range from 20–200 nanometers.
French scientists with the National Centre of Scientific Research at the University of Aix-Marseille (CNRS-AMU) resurrected the 30,000-year-old zombie P. sibericum by exposing sacrificial amoebas to the virus.
‘This is the first time we’ve seen a virus that’s still infectious after this length of time,’ Professor Claverie of CNRS-AMU said at the time.
As Claverie’s co-author on a 2014 PNAS study about the virus, Chantal Abergel, told the BBC: ‘It comes into the cell, multiplies and finally kills the cell. It is able to kill the amoeba – but it won’t infect a human cell.’
Although P. sibericum poses no clear and present danger to either people or animals, the researchers chose their amoeba ‘canaries in the coalmine’ as a way to test the future risks posed by undead pathogens emerging from the thaw.
Along with their co-authors on the new study in Virus this year, Claverie and Abergel called this approach a ‘decisive advantage’ using amoebas as ‘a specific bait to potentially infectious viruses.’
But just the fact that these viruses could be fully revived was a bad sign.
‘The ease with which these new viruses were isolated,’ they wrote, ‘suggests that infectious particles of viruses specific to many other untested eukaryotic hosts [including humans and animals] probably remain abundant in ancient permafrost.’
While the 30,000-year-old P. sibericum virus poses no threat to humans, its present-day ability to kill ameobas portends that more deadly ancient viruses could revived. Above, an ultrathin section of a Pithovirus inside an infected amoeba (credit: Bartoli, Abergel, IGS and CNRS-AMU)
Frozen Mollivirus sibericum was found alongside those same 30,000-year-old Siberian permafrost samples as P. sibericum.
Slightly smaller than P. sibericum (as small as 0.6 micrometers), M. sibericum is another giant virus that’s not a threat to humans or animals — but its proximity to P. sibericum left scientists worried that the permafrost was packed with undead pathogens.
‘We cannot rule out that distant viruses of ancient Siberian human (or animal) populations could reemerge as arctic permafrost layers melt and/or are disrupted by industrial activities,’ Claverie, Abergel and their co-authors wrote in their 2015 study.
Frozen, well-preserved viruses have turned up in mammoth wool, Siberian mummies, prehistoric wolves, and the lungs of an Alaskan Influenza victim. Above, the first full carcass of a cave bear, approximately 39500 years old, unearthed from the Yakutia permafrost in 2020
Scientists now believe that pandemic risks due to permafrost thaw ‘will keep accelerating’ due to climate change. At left, Kotelny Island permafrost melt. At right, Russia has identified about 430 giant permafrost ‘gas bombs’ which could explode forming massive craters in the Arctic
Pandoravirus and Megavirus mammoth
Both the Pandoravirus mammoth and Megavirus mammoth were discovered in 27,000-year-old clump of ice and frozen mammoth wool on the banks of the Yana river in Russia.
Like past ancient giant viruses, P. mammoth and M. mammoth have been shown to be capable of killing amoebas.
Researchers have chosen amoebas as their test ‘canaries’ because these single-celled organisms are close enough to human-like and animal-like eukaryotic cells to be informative, but not close enough to risk creating a new pandemic.
For their study this year, Claverie, Abergel and their team exposed the newfound Pandoravirus strain to another culture of amoebas, as well as to human and mouse cells.
The move was part of a standard protocol to verify that viruses cannot infect mammalian cells.
While both of these viruses fortunately could not infect those human and mouse cells, the researchers don’t think it’s time to breathe a sigh of relief yet.
They wrote that it’s still ‘legitimate to ponder the risk of ancient viral particles remaining infectious and getting back into circulation by the thawing of ancient permafrost layers.’
Both the Pandoravirus mammoth and Megavirus mammoth were discovered in 27,000-year-old clump of ice and frozen mammoth wool on the banks of the Yana river in Russia. Like past ancient giant viruses, both have been shown to be capable of killing amoebas
‘Wolf’ virus (Pacmanvirus lupus)
An ancient relative of African swine fever virus, Pacmanvirus lupus was found thawing from the 27,000-year-old intestines of frozen Siberian wolf.
The remains of this Siberian wolf (Canis lupus) were found at the same Yana riverbed site as the two mammoth viruses.
Like the rest of these large-sized ancient viruses, P. lupus still capable of coming back to life and killing amoebas, even though it’s been out of the game since the Mesolithic or Middle Stone Age.
Ancient relative of African swine fever virus, Pacmanvirus lupus was found thawing from the 27,000-year-old intestines of frozen Siberian wolf. Like the rest, it’s still capable of coming back to life and killing amoebas, even it has been out of the game since the Middle Stone Age
Smallpox needs no introduction. The brutal disease was officially eradicated globally, according to the United Nations World Health Organization, in 1980.
But in 2004, French and Russian scientists found smallpox inside an icy 300-year-old Siberian mummy frozen in the tundra of Russia’s Sakha Republic.
The mummy dates back to hasty graves made during a smallpox outbreak during the late 17th to early 18th centuries in northeastern Siberian region.
Each of the archeological sites consisted of frozen wooden graves buried in the permafrost, but the unusual grave with the smallpox had been stuffed with five frozen mummies.
Individual burials were traditional practice in the region at the time and further analysis suggested to the researchers that the corpses were buried rapidly after their death.
Each of the archeological sites consisted of frozen wooden graves buried in the permafrost, but the unusual grave with the smallpox had been stuffed with five frozen mummies. The 2004 smallpox findings were first published in the The New England Journal of Medicine
Smallpox needs no introduction. The brutal disease was officially eradicated globally, according to the United Nations World Health Organization, in 1980. Above, a smallpox virion, image courtesy of US Centers for Disease Control and Prevention
For the authors of the new paper in Virus, this 2004 smallpox discovery shows just how bad viral eruptions from melting permafrost can get.
‘Probably for safety/regulatory reasons,’ the wrote, ‘there were not follow-up studies attempting to “revive” these viruses (fortunately).’
But that does not mean these viruses could revive on their own, as the rising temperatures continue thawing out the vast northern landscapes of regions like Siberia and Alaska.
‘Very few studies have been published on this subject,’ Claverie, Abergel and their team wrote.