EXTRACTION AND PURIFICATION PATHOGENIC Escherichia coli FOR HUMORAL IMMUNE RESPONSE

In the present investigation, the affected gold fish was obtained from the fish rearing farms and microorganisms were isolated from the organs such as muscle, gill, liver and intestine. The highest microbial load (6.3 ± 0.4 x 107 cfu g-1) was observed in muscle tissue of the infected C. auratus. The lowest microbial load (4.3 ± 0.7 x 104 cfu g-1) was found in intestine of the fish C. auratus. The percentage distributions of mycotic and bacterial isolates are observed. The biochemical characterization of the pathogenic isolates was performed and the microorganisms were identified up to the generic level. Based on the results of lethal concentration and minimum inhibitory concentration test to the isolates, E.coli was found to be highly antigenic to the fish Catla catla and hence E.coli strain was selected for preparation of antigen. From the E.coli strain five different types of antigens such as heat killed antigen, whole cell antigen, heat killed antigen with antiserum, whole cell antigen with antiserum and nucleotide antigens were prepared and injected in to the experimental fish (Catla catla)groups for the study of immunomodulation. Analysis of immunogenicity of antigens against the fish Catla catla was estimated. The E.coli produced β hemolytic pattern on the blood agar plate. B Lymphocytes counts using rosette forming assay revealed significant decrement in pathogens exposed fishes than in control. In conclusion, the results from the present investigation suggest that it is impendingly achievable to develop a commercial vaccine against the E.coli using immune complexes which will overcome the issues of the heterogenicity of the bacterium. It is also possible to improve the vaccine by adding additional antigens to other diseases to this formulation. The aquaculture desperately needs such a formulation to manage and overcome the distressing disease problem caused by the microorganisms. Keywords: Catla catla, Humoral immune response, E.coli and pathogens.