Rhadinovirus
| Rhadinovirus | |
|---|---|
| Virus classification | |
| Group: | Group I (dsDNA)
|
| Order: | |
| Family: | |
| Subfamily: | |
| Genus: | Rhadinovirus
|
| Type species | |
| Saimiriine herpesvirus 2 | |
| Species | |
| |
Rhadinovirus (also known as Rhadinoviridae and gamma-2 herpesviruses) is a genus of viruses in the order Herpesvirales, in the family Herpesviridae, in the subfamily Gammaherpesvirinae. Human and mammals serve as natural hosts. There are currently nine species in this genus including the type species Saimiriine herpesvirus 2.[1][2] Diseases associated with this genus include: Kaposi's sarcoma,[1] primary effusion lymphoma and multicentric Castleman's disease, caused by Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV). The term rhadino comes from the Latin fragile, referring to the tendency of the viral genome to break apart when it is isolated.
Hosts
In general, rhadinoviruses infect lymphocytes and adherent cells, such as fibroblasts, epithelial cells, and endothelial cells and once infection occurs, it is, in general, lifelong. Rhandinoviruses infect a wide range of mammals, include humans. Rhadinoviruses have been found in New World monkeys such as the squirrel monkeys (herpesvirus saimiri) and in mice (murine gammaherpesvirus-68). More recently, both KSHV-like viruses and a new form of rhadinovirus called rhesus rhadinovirus have been discovered in Old World monkeys. These findings suggest that an additional human tumor virus related to KSHV may be found in humans.
Structure
Viruses in Rhadinovirus are enveloped, with icosahedral, spherical to pleomorphic, and round geometries, and T=16 symmetry. The diameter is around 150-200 nm. Genomes are linear and non-segmented, around 180kb in length.[1] They are large double-stranded viruses that possess up to 100 genes in a single long chromosome, which is flanked by repetitive DNA sequences called terminal repeats.
| Genus | Structure | Symmetry | Capsid | Genomic arrangement | Genomic segmentation |
|---|---|---|---|---|---|
| Rhadinovirus | Spherical Pleomorphic | T=16 | Enveloped | Linear | Monopartite |
Life cycle
Viral replication is nuclear, and is lysogenic. Entry into the host cell is achieved by attachment of the viral glycoproteins to host receptors, which mediates endocytosis. Replication follows the dsDNA bidirectional replication model. DNA-templated transcription, with some alternative splicing mechanism is the method of transcription. Translation takes place by leaky scanning. The virus exits the host cell by nuclear egress, and budding. Human and mammals serve as the natural host. Transmission routes are sexual, contact, and saliva.[1]
| Genus | Host details | Tissue tropism | Entry details | Release details | Replication site | Assembly site | Transmission |
|---|---|---|---|---|---|---|---|
| Rhadinovirus | Humans; mammals | B-lymphocytes | Glycoproteins | Budding | Nucleus | Nucleus | Sex; saliva |
Taxonomy
Group: dsDNA
Species Details
- Alcelaphine herpesvirus 1 [3] (AIHV-1) – Malignant catarrhal fever virus
- Alcelaphine herpesvirus 2 [3] (AIHV-2) – Hartebeest malignant catarrhal fever virus
- Ateline herpesvirus 2 (AtHV-2) – Herpesvirus ateles
- Ateline herpesvirus 3
- Bovine herpesvirus 4 (BoHV-4) – Movar virus
- Equid herpesvirus 2 [4] (EHV-2)
- Equid herpesvirus 5 [4] (EHV-5)
- Equid herpesvirus 7 [4] (EHV-7) – Asinine herpesvirus 2
- Hippotragine herpesvirus 1 [3] (HiHV-1) – Roan antelope herpesvirus
- Human herpesvirus 8 (HHV-8) – Kaposi's sarcoma-associated herpesvirus
- Macacine herpesvirus 5 (previously Cercopithecine herpesvirus 17, CeHV-17) – Rhesus rhadinovirus
- Murid herpesvirus 4 (MuHV-4) – Mouse herpesvirus strain 68
- Ovine herpesvirus 2 [3] (OvHV-2) – Sheep-associated malignant catarrhal fever of cattle virus
- Saimiriine herpesvirus 2 (SaHV-2) – Herpesvirus saimiri
Notes
Rhadinoviruses are unique because they have mastered the ability to pirate cellular genes from their host cells and incorporate them into their genomes. For example, most rhadinoviruses have a copy of the cyclin gene, which regulates the ability of the cell to divide. These viruses tend to cause tumors when infection occurs outside of their native hosts or in the case of KSHV, in humans when the host is immunosuppressed due to AIDS, old age, or in the setting of organ transplantation.
References
- ^ a b c d "Viral Zone". ExPASy. Retrieved 15 June 2015.
- ^ a b ICTV. "Virus Taxonomy: 2014 Release". Retrieved 15 June 2015.
- ^ a b c d The Herpesviridae Study Group has proposed that this species be reassigned to the genus Macavirus.
- ^ a b c The Herpesviridae Study Group has proposed that this species be reassigned to the genus Percavirus.