Genus: Betapartitivirus

Genus: Betapartitivirus

Distinguishing features

Members of the genus Betapartitivirus infect plants and fungi. Betapartitiviruses have two dsRNA segments that are believed to be individually encapsidated in separate particles, and genomes typically ranging from 4.34.8 kbp in total.

Virion

Morphology

Based on negative-contrast electron microscopy, the virions of white clover cryptic virus 2 are isometric and approximately 38 nm in diameter (Boccardo et al., 1985). The particles appear rounded and are not penetrated by stain (Figure 1.Betapartitivirus). The structure of Fusarium poae virus 1 has been determined by electron cryomicroscopy and 3D reconstruction (Tang et al., 2010). The outer diameter of the capsid is about 40 nm, and each particle contains 120 CP molecules arranged with icosahedral symmetry (Tang et al., 2010). Other reported betapartitivirus particle sizes range from 25 to 35 nm in diameter (Strauss et al., 2000, Lim et al., 2005, Sasaki et al., 2005, Li et al., 2009, Ziegler et al., 2012).

Figure 1.Betapartitivirus. Negative-contrast electron micrograph of particles of an isolate of White clover cryptic virus 2. The bar represents 50 nm. (Ghabrial et al., 2000).

Physicochemical and physical properties

Virion buoyant density of white clover cryptic virus 2 in CsCl is 1.375 g cm−3 (Boccardo et al., 1985).

Nucleic acid

Viral genome comprises two dsRNA segments, which are each about 2.12.4 kbp. 

Proteins

There is a single major coat protein (CP) with predicted Mr of 7177 kDa. The predicted Mr of the RNA-dependent RNA polymerase (RdRP), as deduced from nucleotide sequence analysis, ranges from 77 to 87  kDa. Virion-associated RNA polymerase activity is present.

Genome organization and replication

Each genome segment is monocistronic: the larger genome segment typically encodes the RdRP and the smaller one encodes the putative CP. Atkinsonella hypoxylon virus has a third dsRNA segment appearing not to encode any proteins (see GenBank record L39127) (Oh and Hillman 1995). Members of genus Betapartitivirus commonly have poly(A) tracts (≥10 nt) near to the coding-strand 3-terminus of one or both genome segments.

Biology

Members of the genus Betapartitivirus infect ascomycetous and basidiomycetous fungi (ten species) and plants (seven species). They are transmitted intracellularly during cell division (plants, fungi) or cell fusion and sporogenesis (fungi). Plant betapartitiviruses include former members of the defunct genus Betacryptovirus, which are associated with persistent infections (Lesker et al., 2013). Various host effects have been described for fungal betapartitiviruses: Rosellinia necatrix virus 1 mediates changes in host colony morphology and decreased dispersal via conidiospores (Kanematsu et al., 2010), and the related, unclassified Sclerotinia sclerotiorum partitivirus 1 reduces the virulence of its host (Xiao et al., 2014).

Species demarcation criteria

The species demarcation criteria within genus Betapartitivirus are:

  • ≤ 90% aa sequence identity in the RdRP, and
  • ≤ 80% aa sequence identity in the CP

Member species

Exemplar isolate of the species
SpeciesVirus nameIsolateAccession numberRefSeq numberAvailable sequenceVirus Abbrev.
Atkinsonella hypoxylon virusAtkinsonella hypoxylon virus2HRNA1: L39125;
RNA2: L39126
All
RNA1: NC_003470;
RNA2: NC_003471
All
Complete genomeAhV
Cannabis cryptic virusCannabis cryptic virusFedora17RNA1: JN196536;
RNA2: JN196537
All
Complete genomeCCV
Cannabis cryptic virusCannabis cryptic virushemp09RNA1: KX709964;
RNA2: KX709965
All
Complete genomeCCV
Ceratocystis resinifera virus 1Ceratocystis resinifera virus 1DengRNA1: AY603052;
RNA2: AY603051
All
RNA1: NC_010755;
RNA2: NC_010754
All
Complete genomeCrV1
Ceratocystis resinifera virus 1Ceratocystis polonica partitivirusCMW7151RNA1: AY247204;
RNA2: AY247205
All
Complete genomeCpPV
Ceratocystis resinifera virus 1Ceratocystis polonica partitivirusCMW2284RNA1: AY260756;
RNA2: AY260757
All
Complete genomeCpPV
Crimson clover cryptic virus 2crimson clover cryptic virus 2IPP_IncarnatSKRNA1: JX971982;
RNA2: JX971983
All
RNA1: NC_038837;
RNA2: NC_038838
All
Complete genomeCCCV2
Dill cryptic virus 2dill cryptic virus 2IPP_hortorumRNA1: JX971984;
RNA2: JX971985
All
RNA1: NC_021147;
RNA2: NC_021148
All
Complete genomeDCV2
Fusarium poae virus 1Fusarium poae virus 1A11RNA1: AF047013;
RNA2: AF015924
All
RNA1: NC_003884;
RNA2: NC_003883
All
Complete genomeFpV1
Fusarium poae virus 1Fusarium poae virus 1240374RNA1: LC150606;
RNA2: LC150607
All
Complete genomeFpV1
Heterobasidion partitivirus 2Heterobasidion partitivirus 2pa1RNA1: HM565953;
RNA2: HM565954
All
RNA1: NC_038839;
RNA2: NC_038840
All
Complete genomeHetRV2
Heterobasidion partitivirus 2Heterobasidion partitivirus 2pa1-bRNA1: KF551880Partial genomeHetRV2
Heterobasidion partitivirus 2Heterobasidion partitivirus 2pa1-cRNA1: KF551881Partial genomeHetRV2
Heterobasidion partitivirus 2Heterobasidion partitivirus 2pa1-eRNA1: KF551882Partial genomeHetRV2
Heterobasidion partitivirus 2Heterobasidion partitivirus 2pa1-fRNA1: KF551883Partial genomeHetRV2
Heterobasidion partitivirus 2Heterobasidion partitivirus 2pa1-dRNA1: KF551884Partial genomeHetRV2
Heterobasidion partitivirus 2Heterobasidion partitivirus 2pa1-gRNA1: KF551885Partial genomeHetRV2
Heterobasidion partitivirus 7Heterobasidion partitivirus 7pa1-aRNA1: JN606091;
RNA2: JN606090
All
RNA1: NC_035485;
RNA2: NC_035486
All
Complete genomeHetRV7
Heterobasidion partitivirus 7Heterobasidion partitivirus 7pa1-bRNA1: KF551886Partial genomeHetRV7
Heterobasidion partitivirus 7Heterobasidion partitivirus 7pa1-cRNA1: KF551887Partial genomeHetRV7
Heterobasidion partitivirus 8Heterobasidion partitivirus 8ir1RNA1: JX625227;
RNA2: JX625228
All
RNA1: NC_038841;
RNA2: NC_038842
All
Complete genomeHetRV8
Heterobasidion partitivirus PHeterobasidion partitivirus PIhrmarkRNA1: AF473549RNA1: NC_043393Partial genomeHetPVP
Hop trefoil cryptic virus 2hop trefoil cryptic virus 2IPP_GelbSKRNA1: JX971980;
RNA2: JX971981
All
RNA1: NC_021098;
RNA2: NC_021099
All
Complete genomeHTCV2
Pleurotus ostreatus virus 1Pleurotus ostreatus virus 1South KoreaRNA1: AY533038;
RNA2: AY533036
All
RNA1: NC_006961;
RNA2: NC_006960
All
Complete genomePoV1
Primula malacoides virus 1Primula malacoides virus 1ChinaRNA1: EU195326;
RNA2: EU195327
All
RNA1: NC_013109;
RNA2: NC_013110
All
Complete genomePmV1
Red clover cryptic virus 2red clover cryptic virus 2IPP_NemaroRNA1: JX971978;
RNA2: JX971979
All
RNA1: NC_021096;
RNA2: NC_021097
All
Complete genomeRCCV2
Rhizoctonia solani virus 717Rhizoctonia solani virus 717717RNA1: AF133290;
RNA2: AF133291
All
RNA1: NC_003801;
RNA2: NC_003802
All
Complete genomeRsV
Rosellinia necatrix virus 1Rosellinia necatrix virus 1OkayamaRNA1: AB113347;
RNA2: AB113348
All
RNA1: NC_007537;
RNA2: NC_007538
All
Complete genomeRnV1
White clover cryptic virus 2white clover cryptic virus 2IPP_LirepaRNA1: JX971976;
RNA2: JX971977
All
RNA1: NC_021094;
RNA2: NC_021095
All
Complete genomeWCCV2

Virus names, the choice of exemplar isolates, and virus abbreviations, are not official ICTV designations.

Related, unclassified viruses

 

Virus name*

 Accession number

dsRNA1/RdRP

dsRNA2/CP

Sclerotinia sclerotiorum partitivirus 1 strain SsPV1-WF-1

JX297511

JX297510

Ustilaginoidea virens partitivirus 3 strain HP-30

KF680478

KF680479

Rosellinia necatrix partititivirus 6 strain W113

LC010952

LC010953

Fusarium poae partitivirus 2

LC150608

LC150609

Virus names and virus abbreviations are not official ICTV designations.
* Representative isolate of a virus with a complete published genome sequence
Defective-interfering RNAs derived from dsRNA1 deposited under GenBank accessions LC062720-27