A new species of 'giant' virus has been revived from a 30,000-year-old sample of Siberian permafrost.

Credit: Chantal Abergel

The first giant virus visible with light microscopy was seen in 2003. Several species have been discovered since, including Pithovirus sibericum (pictured right) found in permafrost in 2014. Jean-Michel Claverie and Chantal Abergel at the CNRS Institute of Microbiology of the Mediterranean in Marseille, France, and their team have now isolated another giant virus from the same piece of permafrost.

They found the virus — named Mollivirus sibericum (pictured left) and seen as spherical particles around 500–600 nanometres in size — multiplying in cultures of amoebas inoculated with the permafrost. Its genome is a double-stranded DNA of 651,523 base pairs, which is unusually devoid of repeats. The authors say that such viruses are probably not rare, and that forms that could infect humans may be reawakened as mining and drilling become more common in the Arctic.

Proc. Natl Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1510795112 (2015)