2016 年 51 巻 4 号 p. 194-198
Red seabream iridovirus (RSIV) was intramuscularly inoculated to rock bream Oplegnathus fasciatus at 11°C, 16°C, 26°C or 28°C to compare the multiplication rates of RSIV in vivo. The rearing temperature at 11°C and 16°C increased at 0.15°C/day, while that at 26°C decreased at 0.11°C/day, along changes of natural water temperatures. After RSIV inoculation at 28°C and 26°C, fish began to die at 11 and 15 days post inoculation, respectively. Their cumulative mortalities were more than 92%. However, no mortality or less than 5% mortality was observed in fish inoculated with RSIV at 11°C or 16°C. The fastest multiplication rate of RSIV was in fish at 28°C, and it was reduced by decreasing fish rearing temperature. Therefore, the virulence of RSIV was affected by fish rearing temperature and the multiplication rate of RSIV. When fish inoculated with different doses of RSIV at 11°C, all of those fish were persistently infected by RSIV for a long period. After water temperature increased to ≥ 20°C, the fish persistently infected by inoculation of RSIV at high intensities developed disease (≥ 78% of mortality), but no mortality occurred in the fish at low intensities of RSIV inoculation. The initial intensity of RSIV infection influenced the mortality of fish with persistently infection of RSIV.
