French scientists bring back to life a giant, still-infectuous virus lying dormant from the Siberian tundra for 30,000 years, raising fears that global warming could unleash other ancient viruses deadly to man.
French scientists have awakened a giant, Stone Age virus – the world’s biggest – locked deep under the ice of Siberia for at least 30,000 years.
The virus, which poses no danger to humans or animals, is so large it can be seen under a microscope, and dates back to the times when mammoths and Neanderthals walked the Earth.
“This is the first time we’ve seen a virus that’s still infectious after this length of time,’ said Professor Jean-Michel Claverie, from the National Centre of Scientific Research, who revived the virus with Chantal Abergel, his fellow researcher and wife.
“Sixty percent of its gene content doesn’t resemble anything on Earth,” Dr Abergel said.
Although harmless, the scientists warned that other viruses that man’s immune system is ill-equipped to deal with might be lurking under the permafrost at risk of being unleashed due to drilling or global warming.
Dubbed Pithovirus sibericum, the virus was found in a 100 foot-deep sample of permanently frozen soil taken from coastal tundra in Chukotka, near the East Siberian Sea.
The team thawed the virus and watched it replicate in a culture in a petri dish, where it infected an amoeba – a simple single-celled organism.
Radiocarbon dating of the soil put the vegetation that grew in it at more than 30,000 years old, according to a paper published in the US journal Proceedings of the National Academy of Sciences.
Modern viruses are tiny and have few genes. The influenza virus, for example, has 13 genes and is about 100 nanometers across. But P. sibericum has 500 genes.
It is the first in a new category of viral giants, a family known as Megaviridae, for which two other categories already exist.
The virus is so big that it can be seen through an optical microscope, rather than the more powerful electron microscope.
The work shows that viruses can survive being frozen for extremely long periods, the French scientists said. They warned that humanity must steel itself for the potential arrival of harmful viruses.
“People will go there; they will settle there, and they will start mining and drilling. Human activities are going to perturb layers that have been dormant for 3 million years,” said Prof Claverie.
“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.
“The risk that this scenario could happen in real life has to be viewed realistically.”