Notes on Genus: Caulimovirus
Type member: Cauliflower mosaic virus
This is one of 7 genera in the family Caulimoviridae
, which are distinctive amongst plant viruses in having double-stranded DNA. Members of the genus Caulimovirus
saic virus group) have large (45-50 nm diameter) icosahedral particles. Characteristic viroplasms are produced in infected plant cells and are the sites for virus replication and particle assembly. The genus was originally very diverse but only those with 6 or 7 open reading frames are now included in this genus.
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 7800-8200 base pairs. Genome has discontinuities in both strands: one in the transcribed (alpha- or minus-) strand and one to three in the non-transcribed strand.
Genus Genomic Organization
Seven open reading frames have been identified. Two RNA transcripts are thought to act as mRNAs for translation of the ORFs.
Type Member Genomic Organization
There are believed to be 7 open reading frames:
|1 ||38 kDa ||Movement protein|
|2 || 18 kDa ||Helper protein involved in aphid transmission |
|3 || 15 kDa || Thought to be a DNA binding protein incorporated into the virion but now known to co-operate with P2 in aphid transmission|
|4 ||57 kDa ||Coat protein (precursor of 42 kDa protein subunit of the virion shell)|
|5 ||79 kDa ||Viral reverse transcriptase|
|6 ||58 kDa ||Inclusion body protein involved in symptom production, host range etc.|
|7 ||11 kDa ||Unknown function|