French scientists found an ancient giant virus named Mollivirus sibericum in a frozen soil sample collected from permafrost in Siberia, which has been sleeping in prehistoric permafrost in the region for over 30,000 years. The newly discovered virus would be the second giant virus discovered in the same area, following the discovery of Pithovirus sibericum in 2014.
Mollivirus sibericum is the fourth type of giant virus following the Minivirus from 2003, the Pandoraviruses found in 2013, and Pithovirus sibericum discovered last year. Their research results were published in the journal of PNAS on September.
“Its (the Mollivirus sibericum) approximately spherical virion (0.6-µm diameter) encloses a 651-kb GC-rich genome encoding 523 proteins of which 64% are ORFans; 16% have their closest homolog in Pandoraviruses and 10% in Acanthamoeba castellanii probably through horizontal gene transfer.”
“M. sibericum is approximately 0.6 μm long—slightly larger than P. sibericum—with 650,000-base-pair genome that codes for more than 500 proteins.” They also explained that compared to other ancient giant viruses, it is more closely to the modern viruses, whose genome is relatively similar to that of the Iridoviridae and Marseilleviridae virus.
When scientists use virus infection spine amoeba (Acanthamoeba) to awake it up, M. sibericum virus can still infect and kill Acanthamoeba even being frozen after so many years. But according to these scientists, M. sibericum virus, like all viruses, can only infect a specific host, and therefore it can be considered no impact on humans and animals. However, they also warned that under the surface there are still unknown ancient virus, and some organisms may be lurking in extreme environments, waiting to wake up.
“If we are not careful, and we industrialise these areas without putting safeguards in place, we run the risk of one day waking up viruses such as small pox that we thought were eradicated,” lead researcher Jean-Michel Claverie, said
Siberian ice is melting slowly since 1970, but in recent years, global warming and increased frequency of human activity brings out the opportunity for the emergence of crisis. Once this type of permafrost is thawing, storing carbon and methane will follow the outflow, which will exacerbate climate change.
Methane is a greenhouse gas with the ability to promote the Earth to absorb solar heat twenty times stronger than carbon dioxide. Methane released due to massive thawing of permafrost, one of the most critical point climatologists worried, will lead to a vicious cycle of global warming.
In addition to methane, the permafrost also stores about 1.7 trillion metric tons of carbon, twice than the amount of the current atmospheric carbon dioxide. It is estimated that in 2100 there will be 120 billion metric tons of carbon flowed, enough to making the average global temperature rise 0.3 degree Celsius.