| Circoviridae | |
|---|---|
Virus classification  | |
| (unranked): | Virus |
| Realm: | Monodnaviria |
| Kingdom: | Shotokuvirae |
| Phylum: | Cressdnaviricota |
| Class: | Arfiviricetes |
| Order: | Cirlivirales |
| Family: | Circoviridae |
| Genera | |
Circoviridae is a family of DNA viruses. [1] [2] Birds and mammals serve as natural hosts. There are 101 species in this family, assigned to 2 genera. Diseases associated with this family include: PCV-2: postweaning multisystemic wasting syndrome; CAV: chicken infectious anemia. [3] [4]
Viruses in the family Circoviridae are non-enveloped, with icosahedral and round geometries, and T=1 symmetry. [2] The diameter is around 20 nm. Genomes are circular and non-segmented, around 3.8kb in length. The capsid consists of 12 pentagonal trumpet-shaped pentamers. [3] There are two main open reading frames arranged in opposite directions that encode the replication and capsid proteins. Alternative start codons are common in the avian species.[ citation needed ]
| Genus | Structure | Symmetry | Capsid | Genomic arrangement | Genomic segmentation |
|---|---|---|---|---|---|
| Cyclovirus | Icosahedral | T=1 | Non-enveloped | Circular | Monopartite |
| Circovirus | Icosahedral | T=1 | Non-enveloped | Circular | Monopartite |
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 |
The family Circoviridae contains two genera— Circovirus and Cyclovirus .
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]
Geminiviridae is a family of plant viruses that encode their genetic information on a circular genome of single-stranded (ss) DNA. There are 520 species in this family, assigned to 14 genera. Diseases associated with this family include: bright yellow mosaic, yellow mosaic, yellow mottle, leaf curling, stunting, streaks, reduced yields. They have single-stranded circular DNA genomes encoding genes that diverge in both directions from a virion strand origin of replication. According to the Baltimore classification they are considered class II viruses. It is the largest known family of single stranded DNA viruses.
Pseudoviridae is a family of viruses, which includes three genera.
Gyrovirus is a genus of viruses, in the family Anelloviridae. Until 2011, chicken anemia virus was the only Gyrovirus identified, but since then gyroviruses have also been identified in humans. Diseases associated with this genus include: chicken infectious anemia, which is associated with depletion of cortical thymocytes and erythroblastoid cells.
Lipothrixviridae is a family of viruses in the order Ligamenvirales. Thermophilic archaea in the phylum Thermoproteota serve as natural hosts. There are 11 species in this family, assigned to 4 genera.
Corticovirus is a genus of viruses in the family Corticoviridae. Corticoviruses are bacteriophages; that is, their natural hosts are bacteria. The genus contains two species. The name is derived from Latin cortex, corticis. However, prophages closely related to PM2 are abundant in the genomes of aquatic bacteria, suggesting that the ecological importance of corticoviruses might be underestimated. Bacteriophage PM2 was first described in 1968 after isolation from seawater sampled from the coast of Chile.
Halspiviridae is a family of viruses that consists of a single genus, Salterprovirus, which consists of a single recognised species; Salterprovirus His1. This virus was isolated from hypersaline water in Australia and was able to be cultured on the halophilic archaeon Haloarcula hispanica. Like many other archaeoviruses, His1 has an approximately limoniform (lemon-shaped) virion.
Bicaudaviridae is a family of hyperthermophilic archaeal viruses. Members of the genus Acidianus serve as natural hosts. There is only one genus, Bicaudavirus, and one species, Acidianus two-tailed virus, in this family. However, Sulfolobus tengchongensis spindle-shaped viruses 1 and 2 are regarded to belong to this family also.
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. It is a single stranded DNA virus (ssDNA). There are 49 species in this genus. Some members of this genus cause disease: PCV-1 is non pathogenic, while PCV-2 causes postweaning multisystemic wasting syndrome (PMWS).
Betabaculovirus is a genus of viruses, in the family Baculoviridae. Arthropods serve as natural hosts. There are 26 species in this genus.
Iotapapillomavirus is a genus of viruses, in the family Papillomaviridae. Rodents serve as natural hosts. There are two species in this genus. Diseases associated with this genus include: cutaneous lesions and benign skin tumours, such as papillomas and keratoacanthomas.
Lambdapapillomavirus is a genus of viruses, in the family Papillomaviridae. Cats and dogs serve as natural hosts. There are five species in this genus. Diseases associated with this genus include: mucosal and cutaneous lesions.
Xipapillomavirus is a genus of viruses, in the family Papillomaviridae. Bovine serve as natural hosts. There are five species in this genus. Diseases associated with this genus include: true papillomas on the cutaneous or mucosal surfaces of cattle.
Zetapapillomavirus is a genus of viruses, in the family Papillomaviridae. Horses serve as natural hosts. There is only one species in this genus: Zetapapillomavirus 1. Diseases associated with this genus include: cutaneous lesions.
Quadriviridae is a family of double-stranded RNA viruses with a single genus Quadrivirus. The fungi Rosellinia necatrix serves as a natural host. The name of the group derives from the quadripartite genome of its members where in Latin quad means four. There is only one species in this family: Rosellinia necatrix quadrivirus 1.
Aveparvovirus is a genus of viruses, in the subfamily Parvovirinae of the virus family Parvoviridae. There are three species in this genus. Diseases associated with this genus include: enteric disease and malabsorption syndrome.
Copiparvovirus is a genus of viruses in subfamily Parvovirinae of the virus family Parvoviridae. Pigs and cows are known to serve as natural hosts. There are seven species in this genus.
Genomoviridae is a family of single stranded DNA viruses that mainly infect fungi. The genomes of this family are small. The genomes are circular single-stranded DNA and encode rolling-circle replication initiation proteins (Rep) and unique capsid proteins. In Rep-based phylogenies, genomoviruses form a sister clade to plant viruses of the family Geminiviridae. Ten genera are recognized in this family.
Redondoviruses are a family of human-associated DNA viruses. Their name derives from the inferred circular structure of the viral genome . Redondoviruses have been identified in DNA sequence based surveys of samples from humans, primarily samples from the oral cavity and upper airway.
Smacoviridae is a family of single-stranded DNA viruses. The genomes of this family are small. The name Smacoviridae stands for 'small circular genome virus'. The genomes are circular single-stranded DNA and encode rolling-circle replication initiation proteins (Rep) and unique capsid proteins. As of 2021, 12 genera and 84 species are recognized in this family. The viruses in this taxon were isolated from faecal samples from insects and vertebrates by metagenomic methods. Little is known about their biology.
Cressdnaviricota is a phylum of viruses with small, circular single-stranded DNA genomes and encoding rolling circle replication-initiation proteins with the N-terminal HUH endonuclease and C-terminal superfamily 3 helicase domains. While the replication-associated proteins are homologous among viruses within the phylum, the capsid proteins are very diverse and have presumably been acquired from RNA viruses on multiple independent occasions. Nevertheless, all cressdnaviruses for which structural information is available appear to contain the jelly-roll fold.
| Authority control databases: National |
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