(Credit: Julia Bartoli and Chantal Abergel, IGS and CNRS-AMU)
Scientists have revived a giant virus after it laid dormant in the Siberian permafrost for over 30,000 years.
It was thought to be dead, found 30 metres deep in the permanently frozen soil of the coastal tundra in Chukotka, near the East Siberia Sea, where the average annual temperature is minus 13.4 degrees Celsius. But when evolutionary biologists Jean-Michel Claverie and Chantal Abergel at the National Centre of Scientific Research (CNRS) at the University of Aix-Marseille in France thawed out the new (old) virus they'd discovered, it came back to life, once again becoming infectious.
But the giant virus, named Pithovirus sibericum, is not dangerous to humans: it only infects amoebas, single-celled organisms, eventually killing the cell.
This is the first time that scientists have seen a virus that is still infectious after 30,000 years (when woolly mammoths and Neanderthals were still thriving), a time span determined by carbon-dating the soil. And this is the biggest seen: 1.5 micrometers in length and containing 500 genes. The influenza virus, for context, has only eight genes.
Although this particular virus is relatively harmless, its arrival should be seen as a warning, Claverie and Abergel said. The pair believe that more serious viruses could be located within the Siberian permafrost — a region that is under threat due to climate change — and, as the permafrost retreats, companies have been looking to the region to mine its natural resources, something Professor Claverie thinks would be a mistake.
"It is a recipe for disaster," he told the BBC. "If you start having industrial explorations, people will start to move around the deep permafrost layers. Through mining and drilling, those old layers will be penetrated and this is where the danger is coming from. If it is true that these viruses survive in the same way those amoeba viruses survive, then smallpox is not eradicated from the planet — only the surface. By going deeper we may reactivate the possibility that smallpox could become again a disease of humans in modern times."
The full study, "Thirty-thousand-year-old distant relative of giant icosahedral DNA viruses with a pandoravirus morphology", can be viewed online in the journal PNAS.