English: Branch 4 of the RNA virus RNA-dependent RNA polymerases (RdRps): dsRNA viruses of eukaryotes and prokaryotes. (A) Phylogenetic tree of the virus RdRps showing ICTV-accepted virus taxa and other major groups of viruses. Approximate numbers of distinct virus RdRps present in each branch are shown in parentheses. Symbols to the right of the parentheses summarize the presumed virus host spectrum of a lineage. Inv., viruses of invertebrates (many found in holobionts, making host assignment uncertain); myco., mycoviruses; uncl., unclassified. Green dots represent well-supported (≥0.7) branches. (B) Genome maps of a representative set of branch 4 viruses (drawn to scale) showing color-coded major conserved domains. Where a conserved domain comprises only a part of the larger protein, the rest of this protein is shown in light gray. The locations of such domains are approximated (indicated by fuzzy boundaries). CapE, capping enzyme; CP, capsid protein; iCP, internal capsid protein; NS, nonstructural protein; NTPase, nucleotide triphosphatase; oCP, outer capsid protein; P, protein; phytoreoS7, homolog of S7 domain of phytoreoviruses; pHel, packaging helicase; vOTU, virus OTU-like protease; VP, viral protein. The CPs of totiviruses and chrysoviruses are homologous to iCPs of reoviruses and cystoviruses (black rectangles).