The Reoviridae family was proposed in 1959 by Sabin to represent respiratory enteric orphan viruses, as they were commonly found in the respiratory and enteric tract, but were not associated with any disease in humans. This name was later found to be misleading as Reoviruses can cause significant disease in humans. The Reoviridae family is composed of 9 genera. The genera Rotavirus, Coltivirus, and Orthoreovirus contain human viruses. Rotaviruses are the major cause of infantile diarrhea and are responsible for almost a million childhood deaths per year, especially in underdeveloped countries. Colitvirus causes Colorado Tick fever, a dengue-like illness as well as encephalitis, in North America. Orthoreoviruses have not yet been linked to specific disease state, although there may be some connection between them and upper respiratory symptoms.


Reoviridae is a family of viruses which are characterized by a double-stranded RNA genome, a spherical shape, and a non-enveloped virion. Unique among viruses, Reoviridae have an outer and inner icosahedral capsid that surround an inner core containing necessary enzymes for mRNA synthesis, including RNA polymerase. It has a segmented genome (Orthoreoviruses have 10, Rotaviruses have 11, and Colitviruses have 12 segments). The genome codes for structural and non-structural genes and can readily reassort, a characteristic exploited by those developing vaccines. They usually have a total size of 18-27 kilobase pairs.