Circovirus


Circovirus is a genus of viruses, in the family Circoviridae. Birds and pigs serve as natural hosts, though dogs have been shown to be infected as well. There are currently 43 species in this genus including the type species Porcine circovirus 1. Some members of this genus cause disease: PCV-1 is non pathogenic, while PCV-2 causes postweaning multisystemic wasting syndrome.

Taxonomy

The following species are recognized:
Viruses in Circovirus are non-enveloped, with icosahedral and Round geometries, and T=1 symmetry. The diameter is around 17 nm. Genomes are circular and non-segmented.
The virions of Circoviruses are surprisingly small, with diameters ranging from 17 up to 22 nm.
GenusStructureSymmetryCapsidGenomic arrangementGenomic segmentation
CircovirusIcosahedralT=1Non-envelopedCircularMonopartite

Life cycle

Viral replication is nuclear. Entry into the host cell is achieved by penetration. Replication follows the ssDNA rolling circle model. DNA templated transcription, with some alternative splicing mechanism is the method of transcription. The virus exits the host cell by nuclear egress, and nuclear pore export.
Birds and pigs serve as the natural host. Transmission routes are fecal-oral and parental.
GenusHost detailsTissue tropismEntry detailsRelease detailsReplication siteAssembly siteTransmission
CircovirusBirds; pigs-Cell receptor endocytosisBuddingNucleusNucleusHorizontal; oral-fecal