birnaviruses

Birnaviruses are a family of non-enveloped RNA viruses that infect a wide range of hosts, including birds, fish, and insects. The family name, Birnaviridae, is derived from "BIRNA," which stands for "Bird RNA virus." These viruses possess a unique genome structure, consisting of two segments of double-stranded RNA (dsRNA). This dsRNA genome is characteristic of the family and plays a crucial role in their replication cycle.

The virion of a birnavirus is typically icosahedral in shape, with a diameter of approximately 50-70 nanometers. They are known for their stability, particularly in the environment, which can contribute to their transmission. Birnaviruses are broadly classified into two genera: Avibirnavirus, which primarily infects birds, and Aquabirnavirus, which infects aquatic animals like fish.

In birds, infectious bursal disease virus (IBDV), an avibirnavirus, is a significant pathogen causing significant economic losses in the poultry industry due to its immunosuppressive effects. In fish, infectious pancreatic necrosis virus (IPNV), an aquabirnavirus, is a major cause of disease and mortality in farmed salmonids and other fish species. The study of birnaviruses is important for understanding viral pathogenesis, host immune responses, and for developing strategies for disease prevention and control in both agricultural and wild populations.