Circoviridae
Circoviridae | |
---|---|
Virus classification | |
(unranked): | Virus |
Realm: | Monodnaviria |
Kingdom: | Shotokuvirae |
Phylum: | Cressdnaviricota |
Class: | Arfiviricetes |
Order: | Cirlivirales |
Family: | Circoviridae |
Genera | |
Circoviridae is a family of
Structure
Viruses in the family Circoviridae are non-enveloped, with icosahedral and round geometries, and T=1 symmetry.
Genus | Structure | Symmetry | Capsid | Genomic arrangement | Genomic segmentation |
---|---|---|---|---|---|
Cyclovirus | Icosahedral | T=1 | Non-enveloped | Circular | Monopartite |
Circovirus | Icosahedral | T=1 | Non-enveloped | Circular | Monopartite |
Life cycle
Viral replication is nuclear. Entry into the host cell is achieved by penetration into the host cell. 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.[2][3] 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. Birds and mammals serve as the natural host. Transmission routes are fecal-oral.[2][3]
Genus | Host | Tissue tropism | Entry | Release | Replication site | Assembly site | Transmission |
---|---|---|---|---|---|---|---|
Cyclovirus | Birds | Chicken: Thymocytes, erythrobalstoid cells; Egg: embryonal tissues and eggshell membrane | Cell receptor endocytosis | Budding | Nucleus | Nucleus | Horizontal: oral-fecal; vertical: bird to egg |
Circovirus | Birds; pigs | None | Cell receptor endocytosis | Budding | Nucleus | Nucleus | Horizontal; oral-fecal |
Taxonomy
The family Circoviridae contains two genera—Circovirus and Cyclovirus.
- Genus Circovirus: type species: Porcine circovirus 1[2]
- Genus Cyclovirus : type species Human associated cyclovirus 8[2][5]
Clinical
A cyclovirus—cyclovirus-Vietnam—has been isolated from the cerebrospinal fluid of 25 Vietnamese patients with CNS infections of unknown aetiology.[6] The same virus has been isolated from the faeces of healthy children and also from pigs and chickens. This suggests an orofaecal route of transmission with a possible animal reservoir.[6]
See also
- Animal viruses