Double-stranded RNA viruses

Double-stranded RNA virus
Electron micrograph of rotaviruses. The bar = 100 nm
Virus classification
Group:	Group III (dsRNA)
Kingdom: Phylum: Class
Orthornavirae Duplornaviricota Pisuviricota Duplopiviricetes

Double-stranded RNA viruses (dsRNA viruses) are a polyphyletic group of viruses that have double-stranded genomes made of ribonucleic acid. The double-stranded genome is used as a template by the viral RNA-dependent RNA polymerase (RdRp) to transcribe a positive-strand RNA functioning as messenger RNA (mRNA) for the host cell's ribosomes, which translate it into viral proteins. The positive-strand RNA can also be replicated by the RdRp to create a new double-stranded viral genome.^[1]

A distinguishing feature of the dsRNA viruses is their ability to carry out transcription of the dsRNA segments within the capsid, and the required enzymes are part of the virion structure.^[2]

Double-stranded RNA viruses are classified into two phyla, Duplornaviricota and Pisuviricota (specifically class Duplopiviricetes), in the kingdom Orthornavirae and realm Riboviria. The two phyla do not share a common dsRNA virus ancestor, but evolved their double strands two separate times from positive-strand RNA viruses. In the Baltimore classification system, dsRNA viruses belong to Group III.^[3]

Virus group members vary widely in host range (animals, plants, fungi, and bacteria), genome segment number (one to twelve), and virion organization (T-number, capsid layers, or turrets). Double-stranded RNA viruses include the rotaviruses, known globally as a common cause of gastroenteritis in young children, and bluetongue virus, an economically significant pathogen of cattle and sheep. The family Reoviridae is the largest and most diverse dsRNA virus family in terms of host range.^[2]