Proteomic analyses of Pandoravirions

With its 2.5 Mb DNA genome packed in amphora-shaped particles of bacterium-like dimension (1.2 µm in length, 0.5 µm in diameter), the Acanthamoeba-infecting Pandoravirus salinus remained the most spectacular and intriguing virus since its description in 2013. Following its isolation from shallow marine sediment off the coast of central Chile, that of its relative Pandoravirus dulcis from a fresh water pond near Melbourne, Australia, suggested that they were the first representatives of an emerging worldwide-distributed family of giant viruses. This was further suggested when P. inopinatum discovered in Germany, was sequenced in 2015. We now report the isolation and genome sequencing of three new strains (P. quercus, P.neocaledonia, P. macleodensis) from France, New Caledonia, and Australia. Using a combination of transcriptomic, proteomic, and bioinformatic analyses, we found that these six viruses share enough distinctive features to justify their classification in a new family, the Pandoraviridae, distinct from that of other large DNA viruses.