Birnaviridae

A family of icosahedral nonenveloped viruses, 60 nm in diameter whose genome consists of two segments of linear double-stranded RNA.

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Bir·na·vi·ri·dae (burґnə-vir″ĭ-de) [bisegmented RNA + virus] the two-segmented double-stranded RNA viruses: a family of RNA viruses having a nonenveloped icosahedral virion 60 nm in diameter with 92 capsomers in a T = 9 arrangement. The genome consists of two segments of linear double-stranded RNA (MW 2.2–2.5 Ч 10⁶ and 2.4–2.6 Ч 10⁶, size of total genome about 6 kbp). Viruses contain five major structural polypeptides and are resistant to light and ultraviolet radiation, heat, lipid solvents, and trypsin. Replication and assembly occur in the cytoplasm; it includes Aquabirnavirus (infecting fish, mollusks, and crustaceans), Avibirnavirus (infecting birds), and Entomobirnavirus (infecting insects).