Genus: Deltapartitivirus


Genus: Deltapartitivirus

Distinguishing features

All members of the genus Deltapartitivirus infect plants. Deltapartitiviruses have two dsRNA segments that are believed to be individually encapsidated in separate particles and the genome is typically 3.13.2 kbp in total.

Virion

Morphology

The virions of pepper cryptic virus 1 and pepper cryptic virus 2 are isometric and approximately 30 nm in diameter (Sabanadzovic and Valverde 2011). 

Physicochemical and physical properties

Virions of beet cryptic virus 2 have a buoyant density of  1.36 g cm−3 in CsCl gradients (Accotto and Boccardo 1986). 

Nucleic acid

Viral genome comprises two dsRNA segments, which are individually about 1.61.7 and 1.41.6 kbp.

Proteins

There is a single major coat protein (CP) with predicted Mr ranging from 38 to 49 kDa. The Mr of the RNA-dependent RNA polymerase (RdRP), as predicted from nucleotide sequence analysis, is  approximately 54 kDa. Virion-associated RNA polymerase activity is present.

Genome organization and replication

Each genome segment is monocistronic: dsRNA1 codes for the RdRP and dsRNA2 codes for the major CP. Additional dsRNA segments representing second versions of dsRNA2 and encoding seemingly full-length capsid proteins with unknown function have been detected in several deltapartitiviruses, including beet cryptic virus 2 (HM560704), Fragaria chiloensis cryptic virus (DQ355439), Raphanus sativus cryptic virus 2 (DQ218038) and Rose cryptic virus 1 (EU413668). Deltapartitiviruses do not usually have long poly(A) tracts near the plus-strand 3-terminus of their genome segments.

Biology

Deltapartitiviruses induce  persistent infections in plants. They are transmitted by ovule and by pollen to the seed embryo.

Species demarcation criteria

The species demarcation criteria within genus Deltapartitivirus are:

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

Member Species

SpeciesVirus name(s)Exemplar isolateExemplar accession numberExemplar RefSeq numberAvailable sequenceOther isolatesOther isolate accession numbersVirus abbreviationIsolate abbreviation
Beet cryptic virus 2beet cryptic virus 2HungaryRNA1: HM560702; RNA2: HM560703; RNA3: HM560704Complete genomeBCV2
Beet cryptic virus 3beet cryptic virus 3XieRNA1: S63913Partial genomeBCV3
Fig cryptic virusfig cryptic virusBN13RNA1: FR687854; RNA2: FR687855RNA1: NC_015494; RNA2: NC_015495Complete genomeFCV
Pepper cryptic virus 1pepper cryptic virus 1Jal01RNA1: JN117276; RNA2: JN117277Complete genomePCV1
Pepper cryptic virus 2pepper cryptic virus 2HW/01RNA1: JN117278; RNA2: JN117279Complete genomePCV2
Pepper cryptic virus 2pepper cryptic virus 2YYRNA1: LC195294; RNA2: LC195295PCV2

Related, Unclassified Viruses 

Virus name*

Accession number

dsRNA1/RdRP

dsRNA2/CP

dsRNA3

Fragaria chiloensis cryptic virus isolate NCGR CFRA 9089

DQ093961

DQ355440

DQ355439

Raphanus sativus cryptic virus 2

DQ218036

DQ218037

DQ218038

rose cryptic virus 1 isolate ShB-1

EU413666

EU413667

EU413668

persimmon cryptic virus isolate SSPI

HE805113

HE805114

 
* Representative isolate of a virus with a complete published genome sequence
Segment encoding the larger version of CP