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The copyright holder for this preprint (which was not peer-reviewed) is the .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 its suppression (e.g., Zamilon). Although the MIMIVIRE mechanism of action is still controversial 14 , the host range of Zamilon has been efficiently expanded to mimiviruses of lineage A by silencing the MIMIVIRE genes 13 and, more recently, by knocking out the putative canonical gene of the system using homologous recombination 15 . The MIMIVIRE system has also been successfully tested in bacteria, restoring susceptibility to antibiotics through the transformation of bacteria with plasmids containing trcg targeting antibioticresistance genes 16 . Nevertheless, host range expansion mediated by spontaneous mutations has never been described in virophages. Moreover, to date, Sputnik, Zamilon and other virophages were almost exclusively challenged with mimiviruses from the three lineages, A-C, but not with distant mimivirus relatives. The only virophage tested with a distant mimivirus was Mavirus. Mavirus replicates only in the marine flagellate Cafeteria roenbergensis coinfected with a distant mimivirus named CroV 17 . Moreover, once this virus begins to replicate, it has been shown that Mavirus acts as an agent of adaptive immunity that protects its host cells from CroV infection 18, 19 .