An ancient virus of unprecedented size has been recovered from 30,000-year-old permafrost in Siberia and reactivated. Incredibly, sixty percent of its genes do not resemble anything currently found on Earth.

The virus, which is so large it can be seen under a microscope, dates back to a time when mammoths, Neanderthals, and early humans walked the Earth. And now it has been revived, bringing new fears that other potentially harmful pathogens could be released by the thawing tundra of Siberia.

The virus, which has been dubbed Pithovirus sibericum after the Greek ‘pithos, meaning a large amphora, is infectious to amoebas but does not appear harmful to human cells. It was found in a 100-foot-deep sample of permanently frozen soil taken from coastal tundra in Chukotka, near the East Siberian Sea, and the detailed findings have just been released in the journal Proceedings of the National Academy of Sciences .

Exploration of the Siberian permafrost is expected to increase as it is thought to contain thirty percent of the world’s oil reserves, gold deposits and other key minerals. There is therefore a danger that viruses which humans have never encountered before, and have no immunity to, could emerge from the ice. “The revival of viruses that are considered to have been eradicated, such as smallpox, whose replication process is similar to that of Pithovirus, is no longer limited to science fiction,” said Professor Jean-Michel Claverie, from the National Centre of Scientific Research, who revived the virus with Chantal Abergel, his fellow researcher and wife. “The risk that this scenario could happen in real life has to be viewed realistically.”

But perhaps the most ground-breaking aspect of the research is the fact that it doesn’t resemble any other virus known on Earth. Modern viruses are tiny and have only few genes. But Pithovirus sibericum contains an incredible 500 genes, placing it in a new category of viral giant, a family known as Megaviridae. “Sixty percent of its gene content doesn’t resemble anything on Earth,” Dr Abergel said.

In a radio interview broadcast on BBC Radio 4's Today programme, Professor Claverie explained that the recently discovered giant virus has been made out of different genetic material than that which is currently known, suggesting it is without any “common history”.

“When we find more and more of those giant viruses it seems to point to some kind of multiple origin of life other than only a single one because they are made of totally different genetic material in a way and so we really wonder where that is coming from. We don’t see any trace of common history”

The implications are huge – if life has “multiple origins” what are they? And where are they from?

Featured image: Depiction of a virus - this is not a true representation of the Pithovirus sibericum

By April Holloway