Common ancestry of herpesviruses and tailed DNA bacteriophages

Comparative analysis of capsid protein structures in the eukaryote-infecting herpesviruses (Herpesviridae) and the prokaryote-iefecting tailed DNA bacteriophages (Caudovirales) revealed a characteristic fold that is restricted to these two virus lineages and is indicative of common ancestry. This fold not only serves as a major architectural element in capsid stability but also enables the conformational flexibility observed during viral assembly and maturation. On the basis of this and other emerging relationships, it seems increasingly likely that the very diverse collection of extant viruses may have arisen from a relatively small number of primordial progenitors.