Chrysoviruses in .

, the fungus that causes rice blast, is the most destructive pathogen of rice worldwide. A number of mycoviruses have been identified. These include viruses 1, 2, and 3 (MoV1, MoV2, and MoV3) belonging to the genus, , in the family, ; partitivirus 1 (MoPV1) in the family, ; chrysovirus 1 strains A and B (MoCV1-A and MoCV1-B) belonging to cluster II of the family, ; a mycovirus related to plant viruses of the family, ( virus A); and a (+)ssRNA mycovirus closely related to the ourmia-like viruses ( ourmia-like virus 1).

A dsRNA mycovirus, Magnaporthe oryzae chrysovirus 1-B, suppresses vegetative growth and development of the rice blast fungus.

A double-stranded RNA (dsRNA) mycovirus was found in isolate S-0412-II 2a of the rice blast fungus Magnaporthe oryzae. Sequence analysis of the five dsRNA segments (dsRNA1 through dsRNA5) revealed that this mycovirus is closely related to Magnaporthe oryzae chrysovirus 1-A (MoCV1-A), tentatively classified as a member of the Chrysoviridae; therefore, it was named Magnaporthe oryzae chrysovirus 1-B (MoCV1-B). Virus particles were spherical and composed of the ORF1, ORF3 and ORF4 proteins.