Genus: Sequivirus


Genus: Sequivirus

Distinguishing features

Virions contain three CPs of about 32-34, 22-26 and 22-24 kDa. The genome consists of a single molecule of ssRNA that encodes a single large polyprotein. The replication block (NTB-Pro-Pol) is contained in the C-terminal region of the polyprotein. The structural protein domains are present in the N-terminal region of the polyprotein but are separated from the N-terminus by a protein domain of about 40-60 kDa. Infectivity of the genome is susceptible to proteinase treatment suggesting the presence of a 5ʹ-linked VPg (Murant et al., 1987). The parsnip yellow fleck virus (PYFV) RNA is not polyadenylated (Turnbull-Ross et al., 1992). This is a unique property within this family. In contrast, the RNA of carrot necrotic dieback virus is polyadenylated (Menzel and Vetten 2008). Tubular structures containing virus-like particles have been observed traversing the cell wall of PYFV-infected cells (Murant et al., 1975). However, their role in cell-to-cell movement has not been investigated and the presence of a movement protein in the polyprotein (possibly upstream of the CPs) needs to be confirmed.

The natural host range of sequiviruses includes species in several plant families. Transmission is by aphids in a semi-persistent manner. However, it is dependent on the presence of a helper virus in the genus Waikavirus (Murant and Gould 1968).

Virion

See discussion under family description.

Genome organization and replication

See discussion under family description.

Biology

See discussion under family description.

Species demarcation criteria

See discussion under family description.

Member Species

SpeciesVirus name(s)Exemplar isolateExemplar accession numberExemplar RefSeq numberAvailable sequenceOther isolatesOther isolate accession numbersVirus Abbreviation(s)Isolate Abbreviation
Carrot necrotic dieback viruscarrot necrotic dieback virusAnthriscusEU980442Complete genomeCNDV
Dandelion yellow mosaic virusdandelion yellow mosaic virusDSM2DQ675189Partial genomeDaYMV
Parsnip yellow fleck virusparsnip yellow fleck virusP121D14066NC_003628Complete coding genomePYFV

Virus names, the choice of exemplar isolates, and virus abbreviations, are not official ICTV designations.
Download GenBank/EMBL query for sequences listed in the table here.