Notes on Genus: Petuvirus
Type member: Petunia vein clearing virus
This is one of 7 genera in the family Caulimoviridae
, which are distinctive amongst plant viruses in having double-stranded DNA. Members of this genus are those with isometric, rather than bacilliform particles and with 1 open reading frame in the genome. The single member of the genus was previously classified in the Caulimovirus
genus, but this now only includes those viruses with 6 or 7 open reading frames. The name is derived from the type member, Petu
nia vein-clearing virus.
Virions isometric, not enveloped, 45-50 nm in diameter with no obvious surface structure. The virion shell is multi-layered.
Virions composed of 16 % nucleic acid.
Monopartite, open circular, double stranded DNA of 7200 base pairs.
Genus Genomic Organization
Although originally thought to have two open reading frames, recent information indicates that there is only one. A methionine tRNA primer-binding site has been identified in the intergenic region.
Type Member Genomic Organization
A single large open reading frame encodes a polyprotein. Various domains have been identified (from the N- to C-terminus):
- Movement protein
- The two distinctive sequence elements [HHCC and DD(35)E] of the integrase function of retroviruses and retrotransposons.
- An RNA-binding element, common to the gag gene of retroelements
- An acid protease
- Reverse transcriptase
- Ribonuclease H