Alphapithovirus

Alphapithovirus is a genus of giant virus known from two species, Alphapithovirus siberiense, which infects amoebae, and Alphapithovirus massiliense. It is DNA-based and is a member of the nucleocytoplasmic large DNA viruses clade. It was discovered in 2014, when a viable specimen was found in a 30,000-year-old ice core harvested from permafrost in Siberia, Russia. It is the third-largest known giant virus, behind only Megaklothovirus horridgei and Klothovirus casanovai.

== Description == The genus name Alphapithovirus, a reference to large storage containers of ancient Greece known as pithoi, was chosen to describe the new species. A specimen of Alphapithovirus measures approximately 1.5 μm (1,500 nm) in length and 0.5 μm (500 nm) in diameter, making it one of the largest viruses yet found, behind only Megaklothovirus and Klothovirus in size. At the time of its discovery in 2014, the Pithovirus was the largest known virus by diameter. It is 50% larger in size than the Pandoraviridae, the previous largest-known viruses, and is larger than Ostreococcus, the smallest eukaryotic cell, although Pandoravirus has the largest viral genome, containing 1.9 to 2.5 megabases of DNA.