Genus Partitivirus

Type Species	Gaeumannomyces graminis virus 019/6-A	(GgV-019/6-A)

Virion Properties

Morphology

Virions are 30-35  nm in diameter. Negatively stained particles are often penetrated by stain giving the appearance of empty particles even though physical data indicate that they contain dsRNA (Fig. 1).

Physicochemical and Physical Properties

Mr of virions is estimated to range from 6 to 9 10⁶. S_20w values range from 101-145. Particles lacking nucleic acid have an S_20w of 66-100S. Virion buoyant density in CsCl is 1.29-1.30 and 1.34-1.36  g/cm³ for particles without and with nucleic acid respectively. Additional density and sedimenting components are found in preparations of some viruses and are believed to comprise replicative intermediates. These consist of particles containing ssRNA and particles with both ssRNA and dsRNA. Virus purification is usually carried out at neutral pH.

Nucleic Acid

Virions contain two unrelated linear dsRNA segments, 1.4-2.2  kbp in size, which are separately encapsidated. The dsRNA segments of the individual viruses are of similar size. Additional segments of dsRNA (satellite or defective) may be present.

Proteins

Virions contain a single major CP, Mr 42-73 10³. Virion-associated RNA polymerase activity is present.

Genome Organization and Replication

The virion-associated RNA polymerase catalyzes in vitro end-to-end transcription of each dsRNA to produce mRNA, by a semi-conservative mechanism. Virions accumulate in the cytoplasm (Fig. 2).

List of Species Demarcation Criteria in the Genus

The criteria to differentiate species in the genus are:

	host range,
	size of dsRNA segments, and
	serological relationships.

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 names, genome sequence accession numbers [ ], and assigned abbreviations ( ) are:

Species in the Genus

Agaricus bisporus virus 4 (Mushroom virus 4)		(AbV-4)
Aspergillus ochraceous virus		(AoV)
Atkinsonella hypxylon virus	[L39125, L39126, L39127]	(AhV)
Gaeumannomyces graminis virus 019/6-A		(GgV-019/6-A)
Gaeumannomyces graminis virus T1-A		(GgV-T1-A)
Penicillium stoloniferum virus S		(PsV-S)
Rhizoctonia solani virus		(RsV)

Tentative Species in the Genus

Diplocarpon rosae virus	(DrV)
Penicillium stoloniferum virus F	(PsV-F)
Phialophora radicicola virus 2-2-A	(PrV-2-2-A)