抄録
Experimental infection of ayu Plecoglossus altivelis with Edwardsiella ictaluri PH-0744 was performed under two different water temperatures, 20°C and 28°C. The strain exhibited higher virulence at 28°C than at 20°C in intraperitoneal injection challenge, with the LD50 values being < 6.0 × 10 CFU/fish at 28°C and 7.4 × 103 CFU/fish at 20°C. In immersion challenge at a dose of 2.5 × 107 CFU/mL for 30 min, mortality of fish was 95% at 28°C and 0% at 20°C. This high virulence of E. ictaluri at 28°C may explain frequent occurrence of E. ictaluri infection of ayu at high water temperature in rivers.
