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Rhadinovirus (synonyms: Rhadinoviridae and gamma-2 herpesviruses) is a genus of viruses in the order Herpesvirales, in the family Herpesviridae, in the subfamily Gammaherpesvirinae. Humans and other mammals serve as natural hosts.<ref name=ViralZone>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name=ICTV>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Diseases associated with this genus include: Kaposi's sarcoma,<ref name=ViralZone/> 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.
SpeciesEdit
The genus consists of the following 12 species:<ref name=ICTV />
- Rhadinovirus atelinegamma2, also called Ateline gammaherpesvirus 2
- Rhadinovirus atelinegamma3, also called Ateline gammaherpesvirus 3
- Rhadinovirus bovinegamma4, also called Bovine gammaherpesvirus 4
- Rhadinovirus colobinegamma1
- Rhadinovirus cricetidgamma2, also called Cricetid gammaherpesvirus 2
- Rhadinovirus humangamma8, commonly called Kaposi's sarcoma-associated herpesvirus and Human herpesvirus 8 (HHV-8)
- Rhadinovirus macacinegamma5, also called Macacine gammaherpesvirus 5
- Rhadinovirus macacinegamma8, also called Macacine gammaherpesvirus 8
- Rhadinovirus macacinegamma11, also called Macacine gammaherpesvirus 11
- Rhadinovirus macacinegamma12, also called Macacine gammaherpesvirus 12
- Rhadinovirus muridgamma4, also called Murid gammaherpesvirus 4
- Rhadinovirus muridgamma7, also called Murid gammaherpesvirus 7
- Rhadinovirus saimiriinegamma2, also called Saimiriine gammaherpesvirus 2
HostsEdit
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. Rhadinoviruses 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 (Murid gammaherpesvirus 68). More recently, both KSHV-like viruses and a new form of rhadinovirus called rhesus rhadinovirus have been discovered in Old World monkeysTemplate:Citation needed. These findings suggest that an additional human tumor virus related to KSHV may be found in humansTemplate:Citation needed.
StructureEdit
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.<ref name=ViralZone /> 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 cycleEdit
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. Humans and other mammals serve as natural hosts. Transmission routes are sexual, contact, and through saliva.<ref name=ViralZone />
| 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 |
NotesEdit
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.
ReferencesEdit
External linksEdit
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