Reoviridae
| Reoviruses | |
|---|---|
 |
|
| Intact double-shelled Rotavirus particles | |
| Virus classification | |
| Group: | Group III (dsRNA) |
| Order: | Unassigned |
| Family: | Reoviridae |
| subfamily | |
Reoviridae is a family of viruses that can affect the gastrointestinal system (such as Rotavirus) and respiratory tract. Viruses in the family Reoviridae have genomes consisting of segmented, double-stranded RNA (dsRNA).[1] The name "Reoviridae" is derived from respiratory enteric orphan viruses.[2] The term "orphan virus" means that a virus that is 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. 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.
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[edit] Structure
Reoviruses are non-enveloped and have an icosahedral capsid (T-13) composed of an outer and inner protein shell.[2] 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 ~ 3.9 kbp – 1kbp and each segment encodes 1-3 proteins. 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).[2]
Since these viruses have dsRNA genomes, replication occurs exclusively in the cytoplasm and the virus encodes several proteins which are needed for replication and conversion of the dsRNA genome into (+)-RNAs. The virus can enter the host cell via a receptor on the cell surface. The receptor is not known but is thought to include sialic acid and junctional adhesion molecules (JAMs). The virus is partially uncoated by proteases in the endolysosome, where the capsid is partially digested to allow further cell entry. The core particle then enters the cytoplasm by a yet unknown process where the genome is transcribed conservatively causing an excess of (+) sense strands, which are used as mRNA templates to synthesize (-) sense strands. Viral particles begin to assemble in the cytoplasm 6–7 hours after infection.
[edit] Genera and type species
Fifteen genera of Reoviridae exist and are divided based on the presence of a "turret" protein on the inner capsid.[3][4]
As of July 2009, ratified by the ICTV, there are two subfamilies; Sedoreovirinae & Spinareovirinae in the family Reoviridae.[5] [6]
"The name Spinareovirinae will be used to identify the subfamily containing the spiked or turreted viruses and is derived from ‘reovirus’ and the Latin word ‘spina’ as a prefix, which means spike, denoting the presence of spikes or turrets on the surface of the core particles. The term ‘spiked’ is an alternative to ‘turreted’, that was used in early research to describe the structure of the particle, particularly with the cypoviruses. The name Sedoreovirinae will be used to identify the subfamily containing the non-turreted virus genera and is derived from ‘reovirus’ and the Latin word ‘sedo’, which means smooth, denoting the absence of spikes or turrets from the core particles of these viruses, which have a relatively smooth morphology."[7]
The subfamily Sedoreovirinae contains 6 genera:
The subfamily Spinareovirinae contains 9 genera:
- Aquareovirus
- Coltivirus
- Cypovirus
- Dinovernavirus
- Fijivirus
- Idnoreovirus
- Mycoreovirus
- Orthoreovirus
- Oryzavirus
Other genera
[edit] Therapeutic applications
The reovirus has been demonstrated to have oncolytic (cancer-killing) properties and has encouraged the development of reovirus-based therapies for cancer treatment.[9]
Reolysin is a formulation of reovirus that is currently in clinical trials for the treatment of various cancers.[10]
[edit] See also
[edit] References
- ^ a b c MicrobiologyBytes - Reoviruses
- ^ Hill, Claire, Booth T et al. (1999). "The structure of a cypovirus and the functional organization of dsRNA viruses". Nature structural biology (Lippincott Williams & Wilkins) 6 (6): 565–569. doi:10.1038/9347. PMID 10360362.
- ^ Knipe, David, Howley P et al. (2006). Fields Virology. Philadelphia, Pa.: Wolters Kluwer, Lippincott Williams & Wilkins. pp. 1855. ISBN 0781760607.
- ^ Carstens, E. B. (January 2010). "Ratification vote on taxonomic proposals to the International Committee on Taxonomy of Viruses (2009)". Archives of Virology (Springer Wien) 155 (1): 133–146. doi:10.1007/s00705-009-0547-x. ISSN 1432-8798. PMID 19960211. http://www.springerlink.com/content/55520571803m75n3/fulltext.pdf.
- ^ "ICTV 2009 MASTER SPECIES LIST VERSION 4". 20 March 2010. http://talk.ictvonline.org/cfs-filesystemfile.ashx/__key/CommunityServer.Components.PostAttachments/00.00.00.12.31/ICTV_2D00_Master_2D00_Species_2D00_List_2D00_2009_5F00_v4.xls[dead link]
- ^ Attoui, Houssam; Mertens, Peter. "Template for Taxonomic Proposal to the ICTV Executive Committee To create a new SubFamily in an existing Family". 2007.127-129V.v2.Spina-Sedoreovirinae. ICTV. pp. 1–9. http://talk.ictvonline.org/files/ictv_official_taxonomy_updates_since_the_8th_report/m/vertebrate-2008/1221.aspx
- ^ Deng XX, Lü L, Ou YJ, Su HJ, Li G, Guo ZX, Zhang R, Zheng PR, Chen YG, He JG, Weng SP (2011) Sequence analysis of 12 genome segments of mud crab reovirus (MCRV). Virology
- ^ Lal R, Harris D, Postel-Vinay S, de Bono J (October 2009). "Reovirus: Rationale and clinical trial update". Curr. Opin. Mol. Ther. 11 (5): 532–9. PMID 19806501.
- ^ Thirukkumaran C, Morris DG (2009). "Oncolytic viral therapy using reovirus". Methods Mol. Biol.. Methods in Molecular Biology 542: 607–34. doi:10.1007/978-1-59745-561-9_31. ISBN 978-1-934115-85-5. PMID 19565924.
[edit] External links
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