Purification and characterization of a new reovirus from the Chinese mitten crab, Eriocheir sinensis.

A new reovirus was recently isolated from a freshwater crab, the Chinese mitten crab, Eriocheir sinensis, in China. The complete viral particles are 55 nm in diameter, icosahedral, non-enveloped and have a mean buoyant density of 1.39 g cm(-3) in CsCl gradient. The viral genome is composed of 12 pieces of dsRNA with an electrophoretic pattern of 3/4/2/3. This virus infects connective tissue of the gills, gut and hepatopancreas. Partial cDNA cloning and sequence analysis showed that the RNA-dependent RNA polymerase is located in the first RNA segment. From its biochemical, ultrastructural and physicochemical properties, this virus is quite different from the genus Aquareovirus (Reoviridae). It may represent a new genus of Reoviridae, different from the other crab reoviruses, P and W(2).