Pathogenicity tests were carried out on Mice, guinea pigs, pigeons and pigs with Edwardsiella tarda broth culture suspension. The results indicated that both the original bacterial cell suspension and normal saline suspension were pathogenic to ull experimentnl!y infectecl anirna!s. The clinical signs noted included fever, anorexia and even to death. Congestion and hemorrhages on ears, chin and abdomen were also observed in infected pigs. The autoptic findings included swelling and peripheral hemorrhages of lymph nodes on various region, hemorrhage and necrosis of some visceral organs. On the other hand, the histopathologic finding revealed typical hemorrhagic and necrotic change. The pathogens were recovered from various visceral organs and parts of blood specimen of pigs inoculated.
Two different concentrations of inactivated trial bacterin were prepared. The potency assay was carried out in mice by intraperitioneal immunization. The potency level of the single dose was the same to that of booster injection after challenge of the two different concentrations of bacterins. The result indicated that the protection potency in 10 times if the bacterin contains 3-4 x109 of organisms per mil-iliter. This experiment strongly suggested that the "Mouse model" could be applied for potency assay on Edwardsiella tarda bacterin.