Their capsids, formed by multiple proteins, have icosahedral symmetry and are arranged generally in concentric layers. The genomes of these viruses consist of 10 to 12 segments of dsRNA, each generally encoding one protein. Reoviridae are currently classified into nine genera. Duplopiviricetes mostly contains plant and fungal viruses and includes the following four families: Amalgaviridae, Hypoviridae, Partitiviridae, and Picobirnaviridae. The class Duplopiviricetes is the second clade of dsRNA viruses and is in the phylum Pisuviricota, which also contains positive-sense single-stranded RNA viruses. The phylum is divided into three classes: Chrymotiviricetes, which primarily contains fungal and protozoan viruses, Resentoviricetes, which contains reoviruses, and Vidaverviricetes, which contains cystoviruses. Apart from RdRp, viruses in Duplornaviricota also share icosahedral capsids that contain 60 homo- or heterodimers of the capsid protein organized on a pseudo T=2 lattice. Duplornaviricota ĭuplornaviricota contains most dsRNA viruses, including reoviruses, which infect a diverse range of eukaryotes, and cystoviruses, which are the only dsRNA viruses known to infect prokaryotes. In the Baltimore classification system, which groups viruses together based on their manner of mRNA synthesis, dsRNA viruses are group III. Based on phylogenetic analysis of RdRp, the two clades do not share a common dsRNA ancestor but are instead separately descended from different positive-sense, single-stranded RNA viruses. Both are included in the kingdom Orthornavirae in the realm Riboviria. Two clades of dsRNA viruses exist: the phylum Duplornaviricota and the class Duplopiviricetes, which is in the phylum Pisuviricota. The family Reoviridae is the largest and most diverse dsRNA virus family in terms of host range. 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. 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). In the Baltimore classification system, dsRNA viruses belong to Group III. Double-stranded RNA viruses evolved two separate times from positive-strand RNA viruses. The two groups do not share a common dsRNA virus ancestor. ĭouble-stranded RNA viruses are classified in two separate phyla Duplornaviricota and Pisuviricota (specifically class Duplopiviricetes), which are in the kingdom Orthornavirae and realm Riboviria. The positive-strand RNA can also be replicated by the RdRp to create a new double-stranded viral genome. The positive-strand RNA may be used as messenger RNA (mRNA) which can be translated into viral proteins by the host cell's ribosomes. The double-stranded genome is used to transcribe a positive-strand RNA by the viral RNA-dependent RNA polymerase (RdRp). Double-stranded RNA viruses ( dsRNA viruses) are a polyphyletic group of viruses that have double-stranded genomes made of ribonucleic acid.
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