OnuMV1c and OnuMV7 are two newly isolated viruses from Ophiostoma novo-ulmi, cause of Dutch Elm (trees) Disease, in Canada. These viruses belong to the genus Mitovirus in the family Narnaviridae.
Mitoviruses are the class of double stranded RNA (dsRNA) viruses found exclusively in mitochondria. They have no capsid and encode an RNA-dependent RNA polymerase (RdRp) needed for RNA replication.
OnuMV1c has high level of similarity in its encoded RdRp to the RdRp encoded by mitovirus OnuMV1b. Researchers are of the opinion that OnuMV1c may have been derived from OnuMV1b through a recombination event and they made their opinion on the bases of the finding of high degree of conservation of the C-terminal regions of OnuMV1c and OnuMV1b and the very low conservation of the N-terminal regions.
On the other hand, OnuMV7 is distinct from any other known Ophiostoma mitovirus and has not been shown to be derived from any other mitovirus. Researchers have reported that OnuMV7 may replicate with a different mechanism than that of the other known mitoviruses and that mechanism could further be studied in future.
Researchers are still not clear about the origin of OnuMV1c and OnuMV7 viruses. There are chances of horizontal transfer from other yet unidentified species.
William E Hintz, Joyce S Carneiro, Irina Kassatenko, Aniko Varga, Delano James (2013). Two novel mitoviruses from a Canadian isolate of the Dutch elm pathogen Ophiostoma novo-ulmi (93–1224) Virology Journal DOI: 10.1186/1743-422X-10-252