Reovirus
| Reoviruses | |
|---|---|
 |
|
| Intact double-shelled Rotavirus particles | |
| Virus classification | |
| Group: | Group III (dsRNA) |
| Order: | Unassigned |
| Family: | Reoviridae |
| Subfamilies and Genera | |
Reoviridae is a family of viruses. They have a wide host range, including vertebrates, invertebrates, plants, and fungi. They are unique in that they lack lipid envelopes and package their genomes of discrete double-stranded segments of RNA within multi-layered capsids. Lack of a lipid envelope has allowed three-dimensional structures of these large complex viruses (diameter,∼600–1,000) to be obtained. There are currently 87 species in this family, divided among 30 genera. Reoviruses can affect the gastrointestinal system (such as Rotavirus) and respiratory tract. The name "Reo-" is derived from respiratory enteric orphan viruses. The term "orphan virus" refers to the fact that some of these viruses have been observed not associated with any known disease. Even though viruses in the Reoviridae family have more recently been identified with various diseases, the original name is still used.
Reovirus infection occurs often in humans, but most cases are mild or subclinical. Rotavirus, however, can cause severe diarrhea and intestinal distress in children. The virus can be readily detected in feces, and may also be recovered from pharyngeal or nasal secretions, urine, cerebrospinal fluid, and blood. Despite the ease of finding Reovirus in clinical specimens, their role in human disease or treatment is still uncertain.
Some viruses of this family infect plants. For example, Phytoreovirus and Oryzavirus. Most of the plant infecting reoviruses are transmitted between plants by insect vectors .The viruses replicate in both the plant and the insect, generally causing disease in the plant, but little or no harm to the infected insect.
Recently researchers at the university of Leeds have found that Reovirus stimulates the body's own immune system to kill off the cancerous cells.
Reoviruses are non-enveloped and have an icosahedral capsid composed of an outer (T=13) and inner (T=2) protein shell. The genomes of viruses in Reoviridae contain 10–12 segments which are grouped into three categories corresponding to their size: L (large), M (medium) and S (small). Segments range from about 0.2 to 3 kbp and each segment encodes 1–3 proteins (10-14 proteins in total). Reoviridae proteins are denoted by the Greek character corresponding to the segment it was translated from (the L segment encodes for λ proteins, the M segment encodes for μ proteins and the S segment encodes for σ proteins).
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