David Prangishvili

From extreme geothermal environments (temperatures above 80°C) in Europe, Asia and North America, we have isolated and characterized more than two dozen different DNA viruses, assigned to 11 viral families, which infect hyperthermophilic members of Archaea, the third domain of life, next to the domains of Bacteria and Eukarya (for review, see Prangishvili, 2013. The Wonderful World of Achaeeal Viruses. Annu. Rev. Microbiol. 67: 565-585). The morphologies of these viruses are exceptionally diverse and include spindle-shaped, two-tailed, bottle-shaped, ovoid, coil-shaped, droplet-shaped and other forms which differ dramatically from those of DNA viruses from pother two domains of life, Bacteria and Eukarya. Moreover, genomes of hyperthermophilic archaeal viruses proved to be terra incognita with overwhelming majority of their genes without homologs in other viruses or cellular life forms. The distinctiveness of these viruses extends to the structures of the proteins they encode and the mechanisms underlying the interactions of these viruses with their hosts.

In my talk, I will summarize the state of art of our studies on hyperthermophilic archeal viruses, and discuss the recent advances towards understanding molecular details of the life cycle of these viruses, their interactions with the host cell, as well as functions and structures of the virus-encoded proteins. In conclusion, I will outline what we have learned about the origin and evolution of viral world and virus-host interactions from the studies on viruses of Archaea and their comparisons with viruses of Bacteria and Eukarya.