Reoviridae

Class III viruses, with a segmented double-stranded RNA genome; there are about 8-10 segments each coding for a different polypeptide and only one strand of the RNA (minus strand) acts as template for mRNA (plus strand). Icosahedral capsid, and the virion includes all the enzymes needed to synthesize mRNA. The viruses originally included in this group do not seem to cause any disease in humans, though they have been isolated from the respiratory tract and gut of patients with a variety of diseases; the name is derived from ‘Respiratory, Enteric, Orphan viruses’. Several pathogenic viruses are now classed as reoviruses including orbivirus, a tick-borne virus that causes Colorado tick fever, and rotavirus.