Family: Birnaviridae

Genus: Aquabirnavirus


Distinguishing features

Viruses in the genus infect fish, possibly molluscs. 


See discussion under family description

Genome organization and replication

See discussion under family description


Aquabirnaviruses have been isolated from a variety of aquatic animals in freshwater, brackish or seawater environments. The ubiquitous nature of these agents and, in some cases, the lack of any association with disease has led to difficulty in assigning nomenclature. The first reports of isolation of infectious pancreatic necrosis virus (IPNV) were limited to epizootics in cultured brook trout (Salvalinus fontinalis). Soon IPNV was found to be responsible for disease in a variety of salmonid fish, including members of the genera Salmo, Salvalinus, and Oncorhynchus. The virus has also been associated with nephritis in Japanese eels (Anguilla japonica), with “spinning disease” in menhaden (Brevoortia tryrannus), and with ascites and cranial hemorrhagic in yellowtail fingerlings (Seriola quinqueradiata). In salmonid fish fingerlings, IPNV causes acute gastroenteritis and destruction of the pancreas. A birnavirus has been associated with hematopoietic necrosis causing high mortalities in turbot (Scophthalmus maximus) with renal necrosis. A non-typical apoptosis has been observed in cultured cells infected by IPNV. 

Species demarcation criteria

Three species of aquabirnaviruses are established, primarily on the basis of the hosts of the member viruses. However, the extremely close genetic relationship between viruses of these species (Figure 4) suggests that there may be a case for combining them into a single species. Aquabirnaviruses do, nevertheless, display considerable antigenic diversity. Based on reciprocal neutralization assays using polyclonal antisera and immunoassays with monoclonal antibodies specific of the capsid protein VP2, isolates within the genus have been grouped into nine cross-reactive serotypes: A1 (type strain West Buxton), A2 (type strain Sp), A3 (type strain Ab), A4 (type strain Hecht), A5 (type Tellina virus 2), A6 (type strain Canada 1), A7 (type strain Canada 2), A8 (type strain Canada 3), and A9 (type strain VR299). Capsid protein sequences correlate well with serological classification and geographical distribution. Six genogroups were defined on the basis of VP2 sequence similarities: while genogroup 1 clusters serotypes A1 and A9, genogroup 2 corresponds to serotypes A7 and A8, genogroup 3 to serotype A3, genogroup 4 to serotypes A5 and A6, genogroup 5 to serotype A2, and genogroup 6 to serotype A4 (Blake et al., 2001). Further sequence characterization of aquabirnaviruses in Asia and Australasia has provided evidence for the existence of an additional genogroup (type strain yellowtail ascites virus) and an enlarged genogroup 5 including the strain NZ10 and relatives. 

Related, unclassified viruses

Virus name

Accession number

Virus abbreviation

marine birnavirus - AY-98

B: AY123970


marine birnavirus - H-1

B: AY129665


Victorian trout aquabirnavirus - 10-04677

A: KP268664; B: KP268679


Tasmanian aquabirnavirus – 98-00208

A: KP268650; B: KP268665


Virus names and virus abbreviations are not official ICTV designations.