A novel bipartite negative-stranded RNA mycovirus of the order Bunyavirales isolated from the phytopathogenic fungus Fusarium sibiricum

A novel negative-stranded RNA mycovirus was isolated from the phytopathogenic fungus Fusarium sibiricum strain AH32. This virus, tentatively named Fusarium sibiricum coguvirus 1 (FsCV1), has a bipartite genome consisting of two RNA segments (RNA1 and RNA2). The negative-sense RNA1 is 6737 nt in length, encoding the RNA-dependent RNA polymerase (RdRp, p251) in the viral complementary (vc) strand. The ambisense RNA2 (1232 nt long) encodes two overlapping proteins: the nucleocapsid protein (NP, p38) in the vc strand and an unknown function protein (UFP, p36) in the viral (v) strand, different from the typical features of Bunyavirales members: the two open reading frames are separated by a long AU-rich intergenic region (IR). Phylogenetic analysis based on the RdRp demonstrated that FsCV1 belongs to the genus Coguvirus, family Phenuiviridae, order Bunyavirales. This is the first report of a coguvirus infecting a fungus.