First evidence of host range expansion in virophages and its potential impact on giant viruses and host cells

Said Mougari; Nisrine Chelkha; Dehia Sahmi-Bounsiar; Fabrizio Di Pinto; Philippe Colson; Jonatas Abrahao; Bernard La Scola

The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/780841 doi: bioRxiv preprint Several studies have reported the occurrence of spontaneous large genomic deletions in dsDNA viruses, including the giant Mimivirus, poxviruses, African swine fever virus (ASFV), and chlorella viruses [43] [44] [45] [46] . In all these viruses, the deletion concerned sequences of several kilobase pairs (kbp) in length located around each end of the virus genomes. The ends of the genomes of these viruses seem to be highly recombinogenic in contrast to the central region, which is more subjected to selective pressures because it contains conserved core genes 43 . For ASFV, the deletion was associated with an enhancement in the capacity of the virus to replicate in Vero cells 45 . For Mimivirus, the loss of genes affected genes encoding fibers and ankyrin repeat-containing proteins. This genetic variation has given rise to a new subpopulation of viruses lacking surface fibers that were resistant to virophage 43 . Spontaneous in-frame deletions have also been reported for several other viruses, including influenza virus, photosynthetic cyanophages and severe acute respiratory syndrome coronavirus (SARS-CoV).