Response of salmonid fish to artificial infection with chum salmon virus

In the fall of 1978, a reovirus was isolated from normal-appearing adult chum salmon (Oncorhynchus keta) returning to the Tokushibetsu Hatchery in Hokkaido, Japan (Winton et al 1981). The chum salmon virus (CSW) was recovered in the chinook salmon (Oncorhynchus tshawytscha) embryo cell line (CHSE-214) where it replicated at 15-20 C, producing foci of syncytia in the monolayer. Electron microscopy revealed icosahedral particles, 75 nm in diameter, with a double capsid. The virus was not inactivated by chloroform or inhibited by fluorodeoxyuridine. It was unstable at 56 C, did not hemagglutinate human type 0 erythrocytes, and had a density of 1.33 g/ml in CsCl . The virus was not neutralized by antiserum against infectious pancreatic necrosis virus or mammalian reovirus serotypes 1, 2 or 3 (Winton 1981). Electrophoretic analysis showed the genome was composed of three large, three medium, and five small segments of double stranded RNA (dsRNA) that ranged from 0.37-2.5 x 10% molecular weight. The virions contained five major structural proteins and several minor proteins (Winton et al 1983).