Ancient virus revived after 30,000 years trapped in ice

Experts warn that global warming and mining could uncover dangerous viruses from the past

LAST UPDATED AT 09:38 ON Tue 4 Mar 2014

A VIRUS from the distant past has been brought back to life by French scientists after lying dormant in the Siberian permafrost for more than 30,000 years

Do I need to worry?

Not immediately. Dubbed Pithovirus sibericum, the virus is harmless to humans and animals. Researchers say it can only infect a type of amoeba called Acanthamoeba.

Still, scientists say that the experiment proves that there is a potential threat that global warming could unlock "unknown pathogens" entombed in frozen soil, as the earth's temperature rises.

Where did the virus come from?

The virus was retrieved from a 30-metre-deep sample of frozen earth found near the coastal tundra in Chukotka, near the East Siberia Sea, AFP reports. The average annual temperature there is minus 13.4 degrees Celsius (7.8 degrees Fahrenheit), which scientists say was key to the virus's survival.

The findings were published in the Proceedings of the National Academy of Sciences (PNAS).

Professor Jean-Michel Claverie, from the National Centre of Scientific Research (CNRS) at the University of Aix-Marseille in France, said: "This is the first time we've seen a virus that's still infectious after this length of time."

Why does it matter?

The Pithovirus sibericum belongs to a class of giant viruses that was first discovered ten years ago. The class is so large that its members can be viewed with a regular optical microscope rather than a more powerful electron microscope. This one measuring 1.5 micrometres in length, is the largest yet found, the BBC reports.

Co-author of the report, Dr Chantal Abergel, also from the CNRS, said: "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."

But researchers warned that other pathogens hidden in permafrost could turn out to be harmful to humans.

"We are addressing this issue by sequencing the DNA that is present in those layers," said Dr Abergel. "This would be the best way to work out what is dangerous in there.''

How secure is Siberia's permafrost?

Researchers say that the area is "under threat". Since the 1970s, Siberian permafrost has "retreated and reduced in thickness". Scientists say that the effects of global warming could speed that process. The region is also being looked at for its natural resources.

Claverie says that any efforts to mine the area could risk exposing new viruses: "It is a recipe for disaster. 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."

But some experts say that it is unlikely many viruses from the past will be capable of becoming active again after thousands of years underground.

Professor Jonathan Ball, a virologist from the University of Nottingham, told the BBC: "Finding a virus still capable of infecting its host after such a long time is still pretty astounding - but just how long other viruses could remain viable in permafrost is anyone's guess. It will depend a lot on the actual virus. I doubt they are all as robust as this one." · 

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