Detection of antibody against Aeromonas salmonicida in the serum of salmonid fish by the enzyme linked immunosorbent assay

Enzyme linked immunosorbent assay (ELISA) using the anti-masu Ig rabbit serum was applied to detect the antibody against Aeromonas salmonicida in the sera of salmonid fish. This ELISA method could detect the antibody in sera of masu (Oncorhynchus masou), chum (O. keta) and coho salmon (O. kisutch) immunized by A. salmonicida and could be applied to detect the antibody against A. salmonicida in sera of matured masu, pink (O. gorbuscha), chum, and kokanee salmon (O. nerka). In 1989, 89 masu and 250 chum salmon, and 59 kokanee were examined to detect antibody against A. salmonicida by ELISA and agglutination test. The number of the fish showing the positive reaction by ELISA, agglutination test and isolation of A. salmonicida were 262, 48, and 33, respectively. In 1990, 200 masu and kokanee salmon fry released from hatchery to river were tested and antibody against A. salmonicida was detected from 111 fish by ELISA, and the incidence of the fish showing the positive reaction was ranged from 4 to 90 %.