In the present study investigation found a bacterial pathogen, Pseudomonas aeroginosa strain, two different of antigens such as whole cell antigen and nucleotide antigens were prepared and injected into the experimental fish (Catla catla) groups and control for the study of humoral mediated immune response and cell mediated immune response. The character study was analysed the fish exposed to different types of antigens in abnormal movement was seen in Nucleotide antigen exposed fish, and low adultation days than in whole cell bacterial antigen. Blood collected from immunized and normal fish for analysis the immune response against the pathogen such as haemagglutination titre, plaque forming assay, and B cell rosette forming assay, T cell counting, DTH response, lymphocyte migration. In both control and experimental groups peak antibody response on nucleotide antigen exposing (10log2) antibody titration value and low in whole cell bacterial antigen(5 log2)antibody titration value compare than control (2log2).The highest value of B cell enumeration against in whole cell bacterial antigen than in nucleotide antigen at 1 st week of time interval. At the 3rd week of interval both types of antigen exposed antibody level as same. Fishes exposed to pathogenic strains 1/10th sublethal concentration for 3 weeks showed a reduction in PFC. The effect of pathogenic strains in direct spleenic plaque forming cells (IgM producing cells) showed a reduction in secondary plaque forming cells in the first 3 weeks and a time and dose dependent in primary and secondary response. The enhancement of this type of immune responses confirms the potential of chosen antigen to be used as a vaccine.
