Orbivirus
4181580
192560830
2008-02-19T14:55:37Z
AndonicO
1792859
Reverted edits by [[Special:Contributions/Banana Guy 2|Banana Guy 2]] ([[User talk:Banana Guy 2|talk]]) to last version by Noah Salzman
{{Taxobox
| virus_group = iii
| familia = ''[[Reoviridae]]''
| genus = '''''Orbivirus'''''
| subdivision_ranks = Species
| subdivision = ''[[African Horse sickness|African horse sickness virus]]''<br>
''[[Bluetongue virus]]''<br>
''[[Epizootic hemorrhagic disease of deer virus]]''<br>
''[[Equine encephalosis virus]]''<br>
''[[Ibaraki virus]]''<br>
''[[Palyam virus]]''
}}
The [[genus]] '''Orbivirus''' is a member of the [[Reoviridae]] [[Family (biology) |family]]. This [[genus]] contains 19 [[species]] and at least 130 different [[serotype]]s. Orbiviruses can infect and replicate within a wide range of arthropod and vertebrate hosts.
==Virus Particles==
Orbiviruses are named after their characteristic [[doughnut]] shaped capsomers (In Latin ''Orbi'' means ring). They have non-enveloped particles that are between 70-80nm in diameter. The [[virus]] particles are spherical in appearance and have [[icosahedral]] symmetry. An outer and an inner [[capsid]] layer surround the [[genome]].
==Genome==
These viruses have double stranded [[RNA]] genomes and therefore are classified as Class III viruses. Their genome is linear and is segmented into 10 segments of various lengths. One copy of each gene segment is packaged per virion. In most cases each gene segment encodes a single open reading frame (ORF).
==Replication==
Many Orbiviruses preferentially infect vascular endothelial cells. Orbiviruses [[Viral entry|enter]] the host cell by [[endocytosis]] and the outer capsid is subsequently removed. The whole cycle of [[viral replication]] takes place within the cytoplasm of the host cell. Transcription of the viral genome into mRNA occurs within the core particle and mRNA is translated into proteins using the host cell ribosomes. Viral proteins are synthesized 2-14 days after initial infection. New virons self-assemble within the cytoplasm and are then released from the host cell by [[budding]]. During the budding process they transiently acquire a lipid envelope which can be detected for a short period of time following their release but this is subsequently lost.
==Pathogenesis==
Orbiviruses primarily cause diseases in animals. The different Orbivirus species have different host specificities. Orbiviruses are vector-borne pathogens transmitted between vertebrate hosts by vectors such as mosquitoes, midges, gnats, sandflies and ticks. Bluetongue virus (BTV) is an Orbivirus that causes [[bluetongue disease]] in sheep, cattle, goats and wild ungulates. BTV has been in the forefront of molecular studies for last three decades and now represents one of the best understood viruses at the molecular and structural levels.<ref name=sobrino7>{{cite book |chapterurl=http://www.horizonpress.com/avir|author=Roy P|year=2008|chapter=Molecular Dissection of Bluetongue Virus|title=Animal Viruses: Molecular Biology|publisher=Caister Academic Press|id=[http://www.horizonpress.com/avir ISBN 978-1-904455-22-6]}}</ref> <ref name=roy2>{{cite book |chapterurl=http://www.horizonpress.com/rnav|author=Roy P|year=2008|chapter=Structure and Function of Bluetongue Virus and its Proteins|title=Segmented Double-stranded RNA Viruses: Structure and Molecular Biology|publisher=Caister Academic Press|id=[http://www.horizonpress.com/rnav ISBN 978-1-904455-21-9]}}</ref> Other species of Orbiviruses are responsible for other diseases of animals such as [[African Horse sickness]] and Colorado Tick Fever.
==See also==
*[[Animal virology|Animal viruses]]
== References ==
{{reflist}}
emedicine Orbivirus
[http://www.emedicine.com/med/topic1675.htm]
Draft of the Orbivirus genus description for the ICTV seventh report
[http://www.iah.bbsrc.ac.uk/virus/Reoviridae/Orbivirus/draft_orbivirus_description.htm]
Mertens, (2001) Orbiviruses and Bluetongue virus. In: Encyclopedia of Life Sciences. John Wiley & Sons, Ltd: Chichester. www.els.net [doi:10.1038/npg.els.0001010]
[[Category:Viruses]]
[[Category:Animal virology]]