A genus of viruses of vertebrates (family Reoviridae) that multiply in arthropods, including certain viruses formerly included with the arboviruses. They are antigenically distinct from other groups of viruses and are characterized by an indistinct but rather large outer layer of capsomeres that give the appearance of rings (hence the name). The genus includes, among others, bluetongue virus of sheep and African horse sickness virus. [L. orbis, ring, + virus]
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or·bi·vi·rus 'ȯr-bi-.vī-rəs n
1) cap a genus of double-stranded RNA viruses of the family Reoviridae that have a genome composed of 10 segments with the core RNA particles having characteristic ring-shaped capsomers and that include the causative agents of African horse sickness and bluetongue
2) any of the genus Orbivirus of reoviruses
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Or·bi·vi·rus (orґbĭ-vi″rəs) [L. orbis circle + virus] orbiviruses; a genus of viruses of the family Reoviridae, separable into at least 14 antigenically distinct groups. They infect a variety of vertebrates and include the human pathogens Orungo virus and Kemerovo virus, as well as the agents of bluetongue and African horse sickness. Mosquitoes, sandflies, and ticks are vectors.Medical dictionary. 2011.