Scientists say an ancient virus that froze in Siberian permafrost 48,500 years ago has become the oldest known so far.
It is among seven permafrost viruses that have been resuscitated after thousands of years.
The youngest has been frozen for 27,000 years, and the oldest, called Pandoravirus yedoma, has been frozen for 48,500 years.
Although the viruses do not pose a danger to humans, scientists warn that other viruses exposed to the melting ice could be “catastrophic” and lead to new epidemics.
The 48,500-year-old virus is the Pandora virus, which infects single-celled organisms known as amoebas. Image A shows the isolated Pandora virus egg-shaped particle with a small hole or opening called an ostiole (white arrowhead). B shows a mixture of pandoravirus and ‘megavirus’ particles with a ‘stargate’ – a white starfish-like structure (white arrowhead)
Pandoravirus yedoma was found in permafrost 52 feet (16 m) below the bottom of a lake at Yukichi Alas in Yakutia, Russia
Revival of viruses
“48, 500 years is a world record,” Jean-Michel Claverie, a virologist at Aix-Marseille University in France, told New Scientist.
Named after Pandora’s Box, pandoravirus is a genus of giant viruses first discovered in 2013, and the second largest in physical size of any known virus genus after pithovirus.
The Pandora virus is 1 micrometer long and 0.5 micrometer wide, which means it can be seen with a light microscope.
This 48,500-year-old specimen was found in permafrost 52 feet (16 meters) below the bottom of a lake in the Yukichi Alas in Yakutia, Russia.
Professor Claverie and colleagues have previously resurrected two 30,000-year-old viruses from permafrost, the first of which was announced in 2014.
All nine viruses are capable of infecting single-celled organisms known as amoebas — but not plants or animals. However, other frozen viruses can be extremely dangerous to plant and animal life, including humans.
Permafrost is ground that remains permanently frozen even during the summer months. In the photo, the ice in the Arctic is melting in the spring
Frost frost and greenhouse gases
Carbon freezes deep in the Arctic permafrost — land that stays completely frozen -32 degrees Fahrenheit (0 degrees Celsius) or colder — for at least two years in a row.
As Earth warms, scientists worry that some of the carbon in permafrost could escape into the atmosphere as carbon dioxide or methane.
Increasing the amount of these gases in the atmosphere could make the Earth’s climate warmer.
More information: US National Ice and Snow Data Center
About 65 percent of Russia’s territory is classified as permafrost – land that remains permanently frozen even during the summer months.
But as temperatures rise due to global warming, the earth is now starting to thaw, coughing up animals and things that have been frozen for thousands of years.
Remains of a woolly rhinoceros that went extinct around 14,000 years ago and a 40,000-year-old wolf’s head – perfectly preserved that still contains fur – have been discovered in recent years.
It even spawned an industry based on the woolly mammoth – which became extinct around 10,000 years ago – as hunters hunt for unearthed skeletons so they can extract their tusks and sell them to ivory traders.
But the discovery of such well-preserved specimens has also prompted fear that diseases the animals may have carried could be frozen with them and, unlike their hosts, might survive thawing.
Professor Clavery warned last year of “very good” evidence that “you can revive bacteria from deep permafrost”.
He even discovered one of these viruses himself—the parovirus—which began attacking and killing amoebae when they thawed from the permafrost.
While the pithovirus, which was frozen for about 30,000 years before the experiment, is harmless to humans, Prof Clavery said it shows that viruses frozen for so long can ‘wake up’ and begin to re-infect the host.
Scientists disagree about the exact age of the Arctic ice cap, the permafrost that surrounds it, and thus the age of the stuff it contains.
A depicted elongated particle of pithovirus (1.9 μm long) showing a single cork-like structure (white arrowhead)
But most of the unfrozen finds unearthed so far date from the last ice age, about 115,000 to 11,700 years ago.
In their paper, Professor Claverie and colleagues say that the release of live bacteria or archaea that have lain in cryptobiosis in permafrost for millions of years is a ‘potential public health concern’.
And they say that “the situation will be more catastrophic in the case of plant, animal or human diseases caused by the revival of an unknown ancient virus.”
“As is unfortunately well documented by recent (and ongoing) epidemics, every new virus, even for well-known families, almost always requires the development of very specific medical responses, such as new antivirals or vaccines.”
The Arctic is of course less populated than other parts of the world, but Professor Clavery said more people are now going there to extract resources such as gold and diamonds.
Unfortunately, the first step in extracting these resources is to strip away the top layers of permafrost, thus exposing people to viruses.
“It is impossible to estimate how long these viruses can remain infectious once exposed to external conditions (UV light, oxygen, heat), and how likely they are to encounter and infect a suitable host in the interval,” says the team.
“But the risk is bound to increase in the context of global warming when the thawing of permafrost continues to accelerate, and more people will live in the Arctic in the wake of industrial projects.”
These nine viruses are further detailed in a new preprint paper, which has not yet been reviewed, on the bioRxiv server.
Last month, scientists warned that the chance of the virus “transferring” to other species increases with the melting of glaciers – slow-moving icebergs.
Melt water from glaciers can transfer pathogens to new hosts, making parts of the Arctic a “breeding ground for emerging epidemics.”
Deadly viruses may be released from melting Arctic ice, study warns
A study says that melting glaciers amid rising global temperatures could be the cause of the next deadly pandemic.
Scientists investigated how climate change affects the risk of “spreading” – a virus jumping to another species – by examining samples from Lake Hazen in the Arctic.
Lake Hazen, seen from above in this NASA image, is the largest Arctic freshwater lake in the world
They found that the chance of an event spreading increases as glaciers melt, as meltwater can transfer pathogens to new hosts.
Experts warn that a warming climate could lead to Arctic viruses coming into contact with new environments and hosts, increasing the risk of this ‘viral spread’.
“Diffusion risks increase with runoff from melting glaciers, a proxy for climate change,” the researchers say in their paper published in Proceedings of the Royal Society B.
“If climate change also shifts the species pool of potential viral vectors and reservoirs north, the high Arctic could become a breeding ground for emerging epidemics.”