1992 Volume 27 Issue 1 Pages 19-27
A new epizootic occurred in red sea bream, Pagrus major, in Shikoku Island in 1990. Diseased fish swam inactively and showed severe anemia with 20-60% mortality. Typically enlarged cells characterized by bathophilic stainability were observed in the spleen, heart, kidney, liver and gill. From the morphology and localization of these cells, they are considered leucocytes. Hexagonal virions were found in the cytoplasm of these cells. Each virion consisted of a central electron-dense core (120 nm) and an electron translucent zone and measured 200-240 nm in diameter. Feulgen staining of the enlarged cells suggested DNA in the virus. These results suggest that the virus belongs to the family Iridoviridae. The virus slowly replicated and produced cytopathic effects of enlarged and rounded cells in RTG-2, CHSE-214, FHM, BF-2 and KRE-3 cells at 20-25°C. Intraperitoneal inoculation of the filtrate (450 nm) of spleen homogenate of the infected fish to red sea bream fingerlings induced similar pathological changes to those observed in spontaneously diseased fish.
