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Baltimore Classification

Higher order taxa

Viruses; Retro-transcribing viruses; Caulimoviridae; Caulimovirus


Blueberry red ringspot virus, Carnation etched ring virus, Dahlia mosaic virus

Description and Significance

The cauliflower mosaic virus and related caulimoviridae viruses infect crucifers, groundnuts, soybeans, and cassava. The cauliflower mosaic virus promoter sequence is used to construct vectors to put genes into transgenic plants. When the virus attacks the host, signs and symptoms may persist or vary seasonally.

Genome Structure

The genome contains a single molecule of circular and is not segmented. The genoms 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 about 8000 nucleotides long. The genome is sequenced but only an estimate is available. The complete sequence is 6800-7771-8175 nucleotides long.

The genome has a guanine+cytosine content of 28-35.5-43 %. 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. (source: ICTV dB Descriptions)

Virion Structure of a Caulimovirus

The virions of a caulimovirus consis of a capsid that is not envelped but round with icosahedral symmetry (T=7). The isometric capsid has a diameter of 35-47.52-50 nm. The capsid shells of 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: ICTV dB Descriptions)

Reproduction Cycle of a Caulimovirus in a Host Cell

The genome of caulivirus replicates in the nucleus or the cytoplasm and involves a reverse transcription step. The virus codes for 7ORFs. Sub-genomic RNA is present in infected cells.

Viral Ecology & Pathology

Caulimoviruses may be transmitted by a vector, mechanical inoculation, grafting or contact between hosts. Caulimovirus is not transmitted by seeds or pollen.

As regards vector transmission, the virus is trasmitted 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.