Immunoprotection of Japanese Flounder Paralichthys olivaceus by Recombinant Vibrio anguillarum Hemolysin

The gene vah4 encoding Vibrio anguillarum hemolysin was cloned and hetelogously expressed. The purified recombinant VAH4 protein was then injected into Japanese flounder Paralichtys olivaceus as an immunogen. Activities of superoxide dismutase, catalase, alkaline phosphatase and acid phosphatase in liver became higher in the immunized group. However, these improvements vanished in 72 h after the injection. VAH4-specific antibodies were detected at a titer of 1:10,240 by ELISA on the 10th day after the injection. In a separate experiment, fish were immunized with VAH4 twice and challenged with V. anguillarum. The immunization with the VAH4 protected fish from V anguillarum infection.