Nodaviridae
Nodaviridae is a family of nonenveloped positive-strand [RNA virus]es. Vertebrates and invertebrates serve as natural hosts. Diseases associated with this family include: viral encephalopathy and retinopathy in fish. There are two genera in the family.
History
The name of the family is derived from the Japanese village of Nodamura, Iwate Prefecture where Nodamura virus was first isolated from Culex tritaeniorhynchus mosquitoes.Virology
Structure
The virus is not enveloped and has an icosahedral capsid ranging from 29 to 35 nm in diameter. The capsid is constructed of 32 capsomers.Genome
The genome is linear, positive sense, bipartite single stranded RNA consisting of 4500 nucleotides with a 5’ terminal methylated cap and a non-polyadenylated 3’ terminal.RNA1, which is ~3.1 kilobases in length, encodes a protein that has multiple functional domains: a mitochondrial targeting domain, a transmembrane domain, an RNA-dependent RNA polymerase domain, a self-interaction domain and an RNA capping domain. In addition, RNA1 encodes a subgenomic RNA3 that encodes protein B2, an RNA silencing inhibitor.
RNA2 encodes protein α, a viral capsid protein precursor, which is auto-cleaved into two mature proteins, a 38 kDa β protein and a 5 kDa γ protein, at a conserved Asn/Ala site during virus assembly.