Caulimovirus
A Viral Biorealm page on the genus Caulimovirus
Baltimore Classification
Higher order taxa
Virus; Retro-transcribing viruses; Caulimoviridae; Caulimovirus
Species
Blueberry red ringspot virus, Carnation etched ring virus, Cauliflower mosaic virus, Cestrum yellow leaf curling virus, Dahlia mosaic virus, Figwort mosaic virus, Horseradish latent virus, Mirabilis mosaic virus, Strawberry vein banding virus
Description and Significance
Cauliflower mosaic virus, in the genus Caulimovirus of the family Caulimoviridae, was the first plant virus discovered to use DNA instead of RNA as its genetic material. Members of this genus are plant pararetroviruses, meaning they use reverse transcription of an RNA intermediate in order to replicate. (sources: Haas et al., Mushegian et al.)
Genome Structure
The genome contains a single molecule of circular and is not segmented. The genome is made of a double stranded DNA and is -RT. Virions do not contain minor species of non-genomic nucleic acid. The complete genome is sequenced, but can only be estimated at about 8000 nucleotides long. It has single-stranded discontinuities at specific sites and the transcribed strand has at least one discontinuity while the non-trnascribed strand has two discontinuities. The genome may have an intergenic poly (A) region. Members of this genus have 6 or 7 open reading frames (ORFs); viruses in the Caulimoviridae family with either more or fewer ORFs have been reclassified into other genera in the family (sources: ICTVdB, Descriptions of Plant Viruses)
Virion Structure of a Caulimovirus
The virions of a caulimovirus consist of a round, non-enveloped capsid that has icosahedral symmetry (T=7). The isometric capsid is 35-47.52-50 nm in diameter. The capsid shells of the caulimovirus virions are composed of multiple layers. The capsids appear round or hexagonal in outline. The capsomer arrangement may be clearly visible or not so obvious. (source: ICTVdB, Mushegian et al.)
Reproduction Cycle of a Caulimovirus in a Host Cell
Replication involves the reverse transcription of an RNA intermediate. (source: Mushegian et al.)
Viral Ecology & Pathology
Caulimoviruses may be transmitted by a vector, mechanical inoculation, grafting or contact between hosts. Caulimoviruses are not transmitted by seeds or pollen. Vector transmission is conducted by insects of the order Hemiptera, family Aphididae. The virus is transmitted in a semi-persistent or non-persistent manner. The vector looses the virus when it moults. The virus does not replicate in the vector and is not transmitted congenitally to the progeny of the vector. (source: ICTVdB)
References
Descriptions of Plant Viruses: Notes on Genus: Caulimovirus.
Haas et al. "Cauliflower mosaic virus : still in the news." Molecular Plant Pathology 3.6 (2002): 419-429.
ICTVdB - The Universal Virus Database, version 4. http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/
Mushegian et al. "Molecular Analysis of the Essential and Nonessential Genetic Elements in the Genome of Peanut Chlorotic Streak Caulimovirus." Virology 206.2 (1995): 823-834.
