Specificity and durability of antibody responses in Atlantic cod (Gadus morhua L.) immunised with Vibrio anguillarum O2b

摘要

Fanning of Atlantic cod (Gadus morhua L.) in Norway is increasing, and vibriosis mainly caused by Vibrio anguillarum serotypes O2a and O2b has been a major disease problem. Although cod juveniles are vaccinated against both the serotypes, outbreaks ofvibriosis in vaccinated fish still occur, sometimes apparently caused by other variants of the bacterium [1]. The immune system of Atlantic cod has been shown to differ from that of other bony fish species so far investigated, in that no increase in antibody levels are detected post-immunization with Vibrio salmonicida [2] or hap ten-carriers [3,4], while low increases in antibody levels are reported to V. anguillarum [5]. Recently, Aeromonas salmonicida was found to induce stronger antibody responsesin cod compared to V. anguillarum, and more individuals immunized with A. salmonicida revealed a response compared to those immunized with V. anguillarum [6]. The antibody responses to both bacterial species were mainly toward lipopolysaccharides (LPS).The reason why only a few cod individuals reveal detectable antibody responses to V. anguillarum is unknown, but they appeared to reveal a highly specific and long lasting response. In the present study, we have compared the specificity of antibodies toV. anguillarum O2b induced in 2 cod individuals [6] with that in rabbit, using immunoblotting. Monoclonal antibodies (mAb) to V. anguillarum O2b was also included in the study.