Circoviridae

Circoviridae
Virus classification
Group:	Group II (ssDNA)
Family:	Circoviridae
Genera
Circovirus Cyclovirus Gyrovirus

The Circoviridae are a family of viruses. These are small, relatively poorly-studied viruses, with circular, single-stranded DNA genomes of approximately one to four kilobases

Virology

The virons are non enveloped about 20 nanometers in diameter with icosahedral symmetry - triangulation number (T) = 1. The capsid consists of 12 pentagonal trumpet shaped pentomers.

The genome is monopartite, circular, single-stranded DNA of between 1.8 to 3.8 kilobases. There are two main open reading frames arranged in opposite directions that encode the replication (Rep) and capsid (Cap) proteins. Alternative start codons are common in the avian species.

The viruses replicate their genomes via a rolling circle mechanism. A stem loop structure with a conserved nonanucleotide motif is located at the 5' intergenic region of circovirus genomes and is thought to initiate rolling-cycle replication.

Taxonomy

The family Circoviridae contains three genera, Circovirus, Cyclovirus and Gyrovirus.

Two circoviruses have been identified in fish - Barbel circovirus (BaCV) 1 and 2.^[1] Their genomes are in length and contain two major open reading frames similar to the capsid and replication associated protein genes found in other circoviruses.

• Genus Circovirus: type species: Porcine circovirus type 1 and 2, beak and feather disease virus (BFDV)^[2]

• Genus Cyclovirus : Dragonfly cyclovirus

• Genus Gyrovirus: type species: Chicken anaemia virus

See also

• Animal viruses

References

1. ^ Lorincz M, Csagola A, Farkas SL, Szekely C, Tuboly T (2011) First detection and analysis of a fish circovirus. J Gen Virol
2. ^ Mankertz P (2008). "Molecular Biology of Porcine Circoviruses". Animal Viruses: Molecular Biology. Caister Academic Press. ISBN 978-1-904455-22-6. http://www.horizonpress.com/avir. 

External links

• ICTVdB Entry for Circoviridae
• ViralZone: Circoviridae