A NEW VIRUS ISOLATED FROM SALMONID FISH

An undescribed virus was isolated from the brain of coho salmon (Oncor hynchus kisutch), iwana (Salvelinus phuvius), rainbow trout (O. mykiss ) and ayu (Plecoglossus altivelis), and ovarian fluid of masu salmon ( O. masou) cultured in the northern part of Japan. The virus was isolat ed from both juveniles and adult fishes. Diseased fish showed abnormal swimming movement and were lethargic. The virus replicated, inducing cytopathic effects and lysis in susceptible cell lines at temperatures of 5 to 25 degrees C. Persistent infection was observed in several fi sh cell lines. The virus particles were enveloped, and were icosahedra l in shape with about 80 nm in diameter with a central electron-dense core. The virus was replicated with IUdR and BVdU, and inclusion bodie s in the infected cells were stained with acridine orange. The virus d ensity was 1.155 g/ml and the viral RNA was 7.3 kb in length. The viru s was stable to pH, diethyl ether and chloroform. The virus was not ne utralized by antisera against known 6 fish viruses.