ICTV virus taxonomy profile: Birnaviridae

Abstract

Birnaviridae is a family of viruses with bi-segmented dsRNA genomes totalling about 6 kbp forming icosahedral, non-enveloped virions. The family includes four genera, members of three of which (Aquabirnavirus, Avibirnavirus and Blosnavirus) infect vertebrates (excluding mammals), whereas members of the fourth genus (Entomobirnavirus) infect insects. Each genus includes 1-3 species. Infectious pancreatic necrosis virus of salmonids and infectious bursal disease virus of poultry are two economically important birnaviruses. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of Birnaviridae, which is available at www.ictv.global/report/birnaviridae.

Keywords: Birnaviridae; ICTV Report; taxonomy.

Fig. 1.

Structure of infectious bursal disease virus particles. (Left) three-dimensional model derived from X-ray crystallography (courtesy of F. Rey) with its T=13 laevo icosahedral shell. (Right) diagram of the distribution of polypeptides and virus genome in particles.

Fig. 2.

Schematic representation of the gene arrangement in the coding strand of genome segment A of birnaviruses, depicting representatives of the four genera: infectious bursal disease virus, infectious pancreatic necrosis virus, blotched snakehead virus and Drosophila X virus. Polyprotein cleavage sites are indicated by a vertical bar. The location and size of the small ORFs are indicated below the polyprotein ORF. Parentheses at the 5′-ends indicate the length of the 5′-non-coding region where known. Segment B of birnaviruses (not shown) encodes VP1 of 840 to 1050 aa.