Immune Response Of Channel Catfish, Ictalurus Punctatus Against The Vaccine Of Several Pathogenic Bacterias

Channel catfish(Ictalurus punctatus Rafinsque) were inoculated with three kind of outer membrane protein(OMP) extracted from Aeromonas hydrophila,Flavobacterium columnare and Edwardsiella ictaluri,respectively.Antiserum with high agglutinating antibody titers and cross-agglutinating antibody titers were obtained from immunized channel catfish.Artificially infected channel catfish were inoculated with the above antiserum and their passive immunity was observed.Results showed that the OMP from the three kind of bacteria all had strong immunogenicity to channel catfish and cross-agglutinating antibody against these three kind of bacteria existed in the immunized channel catfish.Injecting with antiserum can decrease the mortality in artificially infected channel catfish,indicating that antiserum with high antibody titers from immunized channel catfish can provide passive immunity protection against infectious diseases.Channel catfish(Ictalurus punctatus Rafinsque)were immunized with the Vaccine of diseased fish tissue liquit.The immunogenicity of the vaccine of diseased fish tissue liquit to channel catfish were compared by examing the lysozyme activity in serum and phagocytic activity of phagocytes in the blood.The experimental results showed that the lysozyme activity in serum and phagocytic activity of phagocytes in the blood of immunized channel catfish were higher than the control group,and the phagocytic activity and bactericidal activity of phagocytes in the blood and head kidney of channel catfish was significantly boosted and had a high level immune response.The crude LPS of three pathogenic bacteria were thought to have a common protective antigen which cause a cross-immune response to channel catfish.Channel catfish,Ictalurus punctatus Rafinsque,were inoculated with formalin killed Flavobacterium columnare(F-FC),phenol killed F.columnare(P-FC) and heat killed F. columnare(H-FC),respectively.Agglutinating antibody titer and cross-agglutinating antibody titer in the serum,phagocytic activities and bactericidal activities of phagocytes in the head kidney and blood as well as the relative percent survival after challenge with live F.columnare of immunized channel catfish were monitored to study the immune response against three bacterin.The results showed that intraperitoneal inoculation of three bacterin all induced strong immune response in channel catfish.Specific agglutinating antibody and cross-agglutinating antibody against three bacterin were monitored in immunized channel catfish.Phagocytic activities of phagocytes in the head kidney and blood of immunized channel catfish were significantly higher than those of the control group.Challenge with live F.columnare showed that immunized channel catfish gained varying percent survival(RPS) against live F.columnare.