The monotypic genus Avibirnavirus only comprises a viral species of the family Birnaviridae , namely the Infectious Bursitis virus (s. Infectious bursal disease virus : IBDV), which is earlier than Gumboro virus was designated.
The non-enveloped virions of the IBDV are 60 nm in diameter and show icosahedral symmetry with a triangulation number of T = 13. The genome is divided into two segments of double-stranded RNA. Segment A has a size of 3183 bp , segment B of 2715 bp. Two serotypes 1/2 of the IBDV have been described, of which serotype 1 is pathogenic in chickens , whereas serotype 2 does not cause any disease in these.
The virus causes a disease in chickens, infectious bursitis , which is accompanied by inflammation and impairment of the immune system . The virus protein VP2 is able to induce apoptosis in mammalian cells , in particular B lymphocytes are destroyed in the lymph tissue of diseased animals. The virus is highly contagious and spreads worldwide.
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B. Delmas, FSB Kibenge et al .: Genus Avibirnavirus . In: CM Fauquet, MA Mayo et al .: Eighth Report of the International Committee on Taxonomy of Viruses , London, San Diego, 2004, p. 566f