A patch of Russian permafrost from eastern Siberia contained something potentially scary -- a "giant" virus brought back to life after 30,000 years and powerful enough to kill modern single-cell organisms. That's according to French scientists who discovered the ancient virus.
Scientists from France's Aix-Marseille University and other institutions isolated the virus' DNA from a sample of permafrost collected in Chukotka, the Russian region across the Bering Strait from Alaska.
Previously unknown, the virus is now named Pithovirus sibericum. Radiocarbon dating determined it was 30,000 years old, making it the oldest known virus that has been activated, scientists said.
The findings were published online Monday in the Proceedings of the National Academy of Sciences.
Pithovirus sibericum is well deserving of its "giant virus" designation, according to the study. It is the biggest giant virus ever discovered, the study authors said, measuring 1.5 microns in length. The previous biggest virus was 1 micron long.
Giant viruses are so named because of their size -- big enough to be seen with ordinary microscopes and far bigger and more complex than normal viruses and even some bacteria.
So far, the only damage Pithovirus sibericum has done is to single-cell amoebas. The scientists found that the virus, when exposed to the amoebas, quickly multiplied, and the amoebas died within about 12 hours, according to a supporting primer sent by study co-author Chantal Abergel.
There is no danger to humans or animals from Pithovirus sibericum, the primer assures. But other virus perils may lurk in the Arctic's rapidly-thawing permafrost, study authors warn.
The discovery and revival of this giant virus from the depths of the tundra "suggests that the thawing of permafrost either from global warming or industrial exploitation of circumpolar regions might not be exempt from future threats to human or animal health," the study says.
They note that Arctic permafrost has warmed four times as much over the last century as the earth as a whole -- and that commercial interests are eager to exploit the riches that lie below that warming permafrost.
"The rich mineral resources and oil reserves of the arctic regions are under increasing pressure for their industrial exploitation (involving mining and drilling). It thus becomes urgent to examine which viruses are expected to be encountered -- not only near the surface, but in increasingly deeper and more ancient permafrost layers," the study concludes.
The sampled permafrost came from Chukotka's Kolyma region, where rivers have carved cliffs, exposing ancient layers. At those exposed cliffs, samples can be drilled horizontally, avoiding contamination from newer layers.
This particular sample was collected in 2000 by the French scientists' Russian partners, and kept frozen in sterile containers, the primer said. After the Russian scientists were able to regenerate a plant from a 30,000-year-old permafrost layer -- an achievement documented in a 2012 paper published in the Proceedings of the National Academy of Sciences -- the French scientists were inspired to look for ancient viruses.
"The coincidence was that the first virus that we could revive was also the first representative of a new family of giant viruses," the primer said.
The Chukotka region is among those in the Arctic that have become more attractive to resource companies as sea ice retreats. "Mining and drilling means bringing human settlements and digging through these ancient layers for the first time since millions years," the primer said. "If 'viable' virions are still there, this is a good recipe for disaster."
The findings are "interesting and exciting," but not totally unexpected because scientists have long known that viruses can be frozen and stored in laboratories for years, James Van Etten, a University of Nebraska-Lincoln professor of plant pathology, who was not part of the study but who edited the newly published paper, said in an email
But they also raise alarms, Van Etten said.
"Many years ago, during the eradication of the smallpox virus from the planet, there was concern raised that someday one might uncover infectious smallpox viruses from ancient frozen samples. The current finding indicates that it could happen as the permafrost melts due to climate change," he wrote. "My guess is that more viruses will be recovered from the permafrost. How interesting they will be -- no one knows."
Contact Yereth Rosen at yereth(at)alaskadispatch.com
Correction: The preceding report at first used an incorrect unit of measurement to describe the virus. The error has been corrected above.