| At present time, vibriosis is a serious problem for the fish farming industry which caused severe loss in cultured marine fish farms in the North China. Furthermore, vibriosis caused by vibrio anguillarum is common and Vibrio anguillarum is one of the most important bacterial pathogens. To control vibriosis, vaccination is regarded as an ideal strategy. In the present study, the optimization of cultural condition and growth dynamic of V. anguillarum and the formalin and heat-killing conditions of vaccine preparations were studied, and immunological efficacy induced by vaccine preparations of formalin-killed V. anguillarum on Flounder (Paralichthys olivaceus) and Perch (Lateolabraxjanopicus} was measured.In the study of cultural conditions, effects of temperature, salinity, pH, abio-salts and recipes of media on the growth of V. anguillarum were studied. The optimal cultural conditions were obtained. In addition, the formalin and heat-killing conditions were determined. The parameters help to the large-scale vaccine production.Following vaccination, the efficacy of vaccine preparations on fish was studied by using nonspecific immune assays and monitoring specific antibody production (ELISA) and artificial challenge tests. The effect of vaccinations on growth was also determined.The non-specific immune response of fish is often reported as immunological effect of immunostimulants on fish. Immunostimulants can stimulate the natural killer cells, complement, lysozyme, phagocytic cells and increase bactericidal activity and reduce the losses caused by disease in aquaculture. Along immunostimulantants, vaccines have been applying to resist bacterial pathogens in aquaculture. But the nonspecific immune effect of vaccine on fish has been reported very little. By far, the studies on vaccination focus on antibody titer and relative percentage survival. Thus, in this report, following vaccination, the nonspecific immune effect of vaccines on fish was assessed by measuring phagocytic activity of hemocyte and bactericidal activity, lysozyme, SOD, PO and protein concentration in the serum of vaccinated fish. In order to study the ability of the vaccine preparations to induce antibody production, a rabbit-anti-flounder immunoglobulin (Ig) antiserum was produced in the author's laboratory.In the flounder experiment, the results indicated that the vaccinated fish show higher nonspecific immune activity than the unvaccinated fish. Furthermore, the effect of vaccinations on phagocytic activity of hemocyte , bactericidal activity and lysozyme was notable, especially bactericidal activity was the most distinct. Thus, phagocytic activity of hemocyte , bactericidal activity and lysozyme could be regarded as the major indexs to value the efficacy of vaccine on fish. The ELISA assays showed the antibody levels significantly increased in the vaccinated groups and the maximal liter came to 1:512 (group 1), 1:2048 (group2), 1:1024 (group3), respectively. The challenges were performed artificially by intraperitoneal injection with V. anguillarum and the relative percentage survival (RPS) values were 81.25%, 87.50% and 93.75%, respectively. But there seemed to be no complele correlalion belween Ihe RPS and anlibody lilres to V. anguillarum. By challenging with V. parahaemolyticus, the relative percentage survival values were 46.15%,53.85% and 53.85%, respectively. The vaccine preparations showed cross-proteclion against infeclion by V. parahaemolyticus. This verified V. anguillarum and V. parahaemolyticus have common proteclive anligens. In Ihe experiment, Ihe use of adjuvanls in the vaccine resulted in adhesion in the abdominal cavily of vaccinated fish and had a moderately adverse impact on fish weight gain. In addition, the present experiment also indicated that the better immune response would be acquired if the fish were inoculated with a high vaccine density or vaccine emulsified with adjuvant or vaccinated more than one time.In the perch experiment, the fish were inoculated by immersion and revaccinated by immersion...
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