Scientific name Viral Group III | Rank Viral Group | |
Similar Positive‑sense single‑str, Picornavirus, Birnaviridae, Poxvirus, Orbivirus | ||
Double-stranded (ds) RNA viruses are a diverse group of viruses that vary widely in host range (humans, animals, plants, fungi, and bacteria), genome segment number (one to twelve) and virion organization (T-number, capsid layers or turrets). Members of this group include the rotaviruses, known globally as a common cause of gastroenteritis in young children, and bluetongue virus, an economically important pathogen of cattle and sheep.
Contents
Of these families, the Reoviridae is the largest and most diverse in terms of host range.
In recent years the increasing knowledge of virus particle assembly, virus-cell interactions, and viral pathogenesis allow approaches for the development of novel antiviral strategies or agents.
Taxonomy
Viruses with dsRNA genomes are currently grouped into a number of families, unassigned genera and species.
Three families infect fungi: Totiviridae, Partitiviridae and Chrysoviridae. These families have monopartite, bipartite and quadripartite genomes respectively. They are typically isometric particles 25–50 nanometers in diameter. Based on sequence similarity of the RNA dependent RNA polymerase, the partitiviruses are probably derived from a totivirus ancestor. A fourth family — Alternaviridae — has recently been described also with quadripartite genome.
Hypoviruses are mycoviruses (fungal viruses) with unencapsidated dsRNA genomes. They may have common ancestry with plant positive strand RNA viruses in supergroup 1 with potyvirus lineages, respectively
A new clade (as yet unnamed) of six viruses infecting filamentous fungi has been reported.
Taxa
Families
Unassigned species
Anti-virals
Since cells do not produce double-stranded RNA during normal nucleic acid metabolism, natural selection has favored the evolution of enzymes that destroy dsRNA on contact. The best known class of this type of enzymes is Dicer. It is hoped that broad-spectrum anti-virals could be synthesized that take advantage of this vulnerability of double-stranded RNA viruses.