HISTOPATHOLOGY OF VIRAL DEFORMITY IN YELLOWTAIL FINGERLING, SERIOLA-QUINQUERADIATA

Histopathological changes assoicated with the infection of viral defor mity virus (VDV) were described in yellowtail fingerlings, Seriola qui nqueradiata, from a hatchery in Nagasaki Prefecture. Advanced congesti on in the liver, edema and anemia in the kidney, anemia in the spleen and congestion in the various parts of the brain were observed in natu rally diseased fish. Experimentally infected fish showed congestion an d focal necrosis in the liver, vacuolar degeneration in tubular epithe lial cells and edematous changes in the hematopoietic tissue of kidney , and extensive anemia and necrosis of the splenic tissues. In the bra in of fish showing abnormal swimming behavior and deformity, advanced congestion and hemorrhage were found in all fish examined. Histopathol ogical features in experimentally infected fish closely resembled thos e in naturally diseased fish. These findings suggest that lesions in t he brain are related to abnormal swimming behavior and deformity of th e diseased fish.