A new virus from the plant pathogenic oomycete Phytophthora infestans with an 8 kb dsRNA genome: the sixth member of a proposed new virus genus.

A virus designated Phytophthora infestans RNA virus 3 (PiRV-3) was characterized from an isolate of P. infestans that was co-infected with a second previously described virus, PiRV-4, a member of the virus family Narnaviridae (Cai et al., 2012). The genome of PiRV-3 is 8112 nt and one strand, designated the positive strand, has two deduced overlapping open reading frames linked by a potential frameshift sequence. The first open reading frame (ORF1) is predicted to encode a protein of unknown function, and ORF2 is predicted to encode an RNA-dependent RNA polymerase (RdRp) most closely related to six unclassified dsRNA viruses of filamentous fungi. The genome organizations of five of the related viruses are similar to PiRV-3, indicating taxonomic linkage among those viruses. We suggest that PiRV-3 and related viruses should be collected into a new virus taxon.