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Table 5 Evolutionary connections between prokaryotic and eukaryotic viruses and related selfish genetic elements

From: The ancient Virus World and evolution of cells

Lineages of eukaryotic viruses Lineages of prokaryotic viruses Shared genes Type of relationships References
Positive-strand RNA viruses Positive-strand RNA bacteriophages (MS2, etc) RdRp Possible direct vertical link (monophyly) although capsid proteins of RNA phages are unrelated to those of eukaryotic viruses [87]
Retroid viruses and elements Retrons, group II introns RT Possible direct vertical relationship although eukaryotic viruses/elements have many additional genes including proteases and virion components; none of the prokaryotic elements have capsids. [32, 103, 104]
Parvoviruses, papovaviruses, circoviruses, geminiviruses, helitron transposons Small DNA bacteriophages (e.g., φX174) and plasmids RCRE Generic evolutionary relationship linked to the common mode of replication [17–19]
Adenoviruses Tailed bacteriophages with genome-linked terminal proteins (e.g., PRD1) JRC, DNA polymerase, terminal protein, packaging ATPase Possible direct relationship suggested by the coherent set of conserved proteins [116]
Herpesviruses Tailed bacteriophages JRC, large terminase subunit, UL9 helicase, DNA polymerase, assemblin (virion morphogenetic protease) Possible direct relationship suggested by the coherent set of conserved proteins. However, a more complex relationship with different phages might be more likely [109, 117]
Nucleo-Cytoplasmic Large DNA viruses (NCLDV) Tailed bacteriophages, plasmids JRC, S3H, primase, packaging ATPase, Holliday junction resolvase, helicases Complex relationships with different groups of phages and plasmids; in particular, the fusion primase-S3H protein most closely resembles a homolog from archaeal plasmids. [53, 107]