| Orthoreovirus | |
|---|---|
| Virus classification | |
| Group: | Group III (dsRNA) |
| Order: | Unassigned |
| Family: | Reoviridae |
| Subfamily: | Spinareovirinae |
| Genus: | Orthoreovirus |
| Type species | |
| Mammalian orthoreovirus |
|
| Species | |
|
Avian orthoreovirus |
|
Orthoreoviruses are members of the Reoviridae virus family. They have double stranded RNA genomes and are therefore group III viruses. These viruses infect vertebrates (including humans) but no disease symptoms are normally seen. In some cases however, orthoreovirus infection can lead to complications, especially in mice and birds.
The structure of the virus particles is complex. The virus is non-enveloped and has icosahedral symmetry with a triangulation number of 13. It can be compared to a wheel with spokes radiating out of it. The virus has a double protein shell. The outer shell is approximately 80 nm in diameter and the inner shell is 60 nm in diameter.
The genome can be divided into three main classes: L (large), M (medium) and S (small). The L genes encode λ proteins, the M genes encode μ proteins and the S genes encode σ proteins. σ1, σ3, λ2 and μ1c proteins make up in the outer capsid. Proteins λ1, λ3, σ2 and μ2 make up the inner capsid.
Replication of the virus takes place in the host cell cytoplasm.
Like other members of the Reoviridae family, the reoviruses are non-enveloped and characterized by concentric capsid shells that encapsidate a segmented dsRNA genome. A reovirus has eight structural proteins and ten segments of dsRNA. A series of uncoating steps and conformational changes accompany cell entry and replication. High-resolution structures are known for almost all of the proteins of mammalian reovirus (MRV), which is the best-studied genotype. Electron cryo-microscopy (cryoEM) and X-ray crystallography have provided a wealth of structural information about two specific MRV strains, type 1 Lang (T1L) and type 3 Dearing (T3D).[1]