Evolutionary insights from studies on viruses of hyperthermophilic archaea

The morphological diversity of viruses which parasitize hyperthermophilic archaea thriving at temperatures greater than or equal to80 degreesC appears to exceed that of viruses of prokaryotes living at lower temperatures. Based on assumptions of the existence of viruses in the prebiotic phase of evolution and hot origins of cellular life, we suggest that this remarkable diversity could have its source in ancestral diversity of viral morphotypes in hot environments. Attempts are made to trace evolutionary relationships of viruses of hyperthermophilic archaea with other viruses. (C) 2003 Editions scientifiques et medicales Elsevier SAS. All rights reserved.