Genus: Rhizidiovirus

Chapter Version: ICTV Ninth Report; 2009 Taxonomy Release

Virion properties

Morphology

Virions are isometric, 60 nm in diameter (Figure 1).

Physicochemical and physical properties

The buoyant density of virions in CsCl is 1.31 g cm⁻³; S_20,w is 625. Virions contain 10% nucleic acid.

Nucleic acid

Virions contain a single molecule of dsDNA with a Mr of 16.8 10⁶ and a G+C ratio of 42%.

Proteins

Virions contain at least 14 polypeptides with sizes in the range of 26−84.5 kDa.

Lipids

None reported.

Carbohydrates

None reported.

Genome organization and replication

Particles appear first in the nucleus.

Biological properties

The virus appears to be transmitted in a latent form in the zoospores of its host Rhizidiomyces sp. Activation of the virus, which occurs under stress conditions such as heat, poor nutrition, or aging, results in cell lysis. Rhizidiomyces sp. is a water mold belonging to the kingdom Protista (Chromalveolata); it is no longer classified in the kingdom Fungi. Therefore, there are currently no recognized dsDNA viruses that naturally replicate in fungi.

No research has been done on this dsDNA virus system since 1983.

Species demarcation criteria in the genus

Not applicable.

List of species in the genus Rhizidiovirus

Species names are in italic script; names of isolates are in roman script. Sequence accession numbers [ ] and assigned abbreviations ( ) are also listed.

List of other related viruses which may be members of the genus Rhizidiovirus but have not been approved as species

None reported.

Similarity with other taxa

None reported.

Derivation of name

Rhizidio: from name of the host Rhizidiomyces sp.

Further reading

Dawe, V.H. and Kuhn, C.W. (1983). Virus-like particles in the aquatic fungus, Rhizidiomyces. Virology, 130, 10-20.

Dawe, V.H. and Kuhn, C.W. (1983). Isolation and characterization of a double-stranded DNA mycovirus infecting the aquatic fungus, Rhizidiomyces. Virology, 130, 21-28.

Contributed by

Ghabrial, S.A.