Genus Mitovirus

Type Species	Cryphonectria parasitica mitovirus 1-NB631	(CpMV1-NB631)

Virion Properties

No virions have been reported for members of this genus.

Nucleic Acid

A single segment of dsRNA of 2.7  kb can be isolated from mitochondria of infected isolates. No poly(A) tail is associated with the 3-end of the putative coding strand of the dsRNA. A single-stranded RNA of 2.7  kb, also without a poly(A) tail, is present in infected tissue. No large protein was identified from cell-free translations charged with melted dsRNA or in vitro transcripts representing the putative coding strand.

Proteins

No structural proteins were identified in the dsRNA-containing mitochondrial fraction of Cryphonectria parasitica mitovirus 1-NB631 (CpMV1-NB631)-infected tissue.

Antigenic Properties

None reported.

Genome Organization and Replication

The putative coding strand of CpMV1-NB631 is predicted to be translatable only in mitochondria, not in cytoplasm. When mitochondrial codon usage is invoked, the deduced translation product is a putative 97 10³ protein containing RNA-dependent RNA polymerase motifs. No large polypeptide is predicted from the complementary strand in cytoplasmic or mitochondrial translation. No details of replication are known.

Biological Properties

The virus infects members of the chestnut blight fungus, Cryphonectria parasitica. Confirmed member viruses reduce virulence of the fungus (i.e., cause “hypovirulence”). CpMV1-NB631 is localized in mitochondria. It can be transmitted to uninfected strains by hyphal fusion (anastomosis). The transmission rate of CpMV1-NB631 through conidia is 100%. Transmission through ascospores occurs at 20-50% when the infected parent is the female in matings, but does not occur when the infected parent is male in matings.

List of Species Demarcation Criteria in the Genus

Not applicable.

List of Species in the Genus

Official virus species names are in italics. Tentative virus species names, alternative names ( ), strains or serotypes are not italicized. Virus name, genome sequence accession number [ ], and assigned abbreviation ( ) are:

Species in the Genus

Cryphonectria parasitica mitovirus 1-NB631	[L31849]	(CpMV1-NB631)

Tentative Species in the Genus

None reported.

List of Unassigned Viruses in the Family

None reported.

Phylogenetic Relationships within the Family

Not available.

Similarity with Other Taxa

None reported.

Derivation of Names

Mito: sigla from mitochondrial.

Narna: sigla from naked RNA virus.