Study On Impact Of Immune Functions Of Different Immunostimulants For Aquatic Animals

1.Channal catfish (Ictalurus punctatus Rafinsque) were immunized with crude lipopolysaccharide (LPS) extracted from Cytophaga columnaris, Aeromonas hydrophila and Edwardsiella ictaluri. The immunogenicity of crude lipopolysaccharide to channal catfish were compared by examing the agglutinating antibody titers, cross-agglutinating antibody titers of serum, the phagocytic activity and bactericidal activity of phagocytes in the blood and head kidney. The experimental results showed that the agglutinating antibody titers and cross-agglutinating antibody titers 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.2.Carassius auratus was immunized by injecting with lipopolysaccharide(LPS), outer membrane protein(OMP)extracted from psychrophilic bacteria.Different time after the injection, influence of two antigens on immunological function of Carassius auratus was determined by testing the lysozyme activity, antibactericial activity, phenoloxidase activity in serum , the PP and PI of white blood cell, and the number of leucocytes change in blood of Carassius auratus.The result showed that two antigens have higher immunogenicity, compared with the examing of the control, the differences between the various index were very significant higher.3.Bacterial flour was used as a food additive to test the immune function of Macrobrachium nipponensis. The results showed that the Po, Ua, U1 and phagocytic activity of the test groups are significantly higher than those of the controll groups. after the Aeromonas hydrophila was injected to the Macrobrachium nipponensis, which can strengthen their resistance against Aeromonas hydrophila.indicating the effectiveness of bacterial flour on enhancing Po, Ua, U1 and phagocytic activity of M. nipponense, leading to an increase in the immunnological activities.Further studies are needed to identify the mechanism of bacterial flour in immune function.4.To determine the effects of immunity-stimulants on innate immune response of Carassius auratus, fish were fed diets containing 0 (control), 0.2% , 0.5%, 0.8%immunity-stimulants for 1, 4, 7, 14 and 21 days. The results showed that the phagocytic activities were greatly increased and the lysozyme activities were obviously enhanced. This significant difference of the lysozyme activities disappeared 7d after the fish stopped feeding mixed diet(P＞0.05), but this significant difference of the phagocytic activities were obviously holding(P＜0.05).