Immune Efficacy Of Edwardsiella Tarda Ghosts Vaccine For Oreochromis Niloticus By Different Inoculation Routes

Edwardsiella tarda is one of the important pathogens in aquaculture, caused prevalent diseases in marine, freshwater aquaculture animals in the world, and caused serious economic losses to aquaculture industry. Currently,disinfectants, antibiotics and other chemicals are still main way to prevent and treat bacterial disease caused by Edwardsiella tarda, but there are many problems happen such as bacterial resistance, drug residues in aquaculture food.Bacterial ghosts are bacterial shell having no cytoplasm and reproductive capacity making by the expression of gene E of PhiX174 phage lysis in Gram-negative bacteria.Because there is no pathogenic role like viable bacteria,and is a natural adjuvant properties containing stimulating complexes such as natural immune LPS,lipid, peptidoglycan,etc.contained in the natural stimulating complexes having adjuvant properties,compliance with no environmental pollution and no drug residues in aquatic food, etc. It is suitable as a candidate vaccine to study the immune protective effect and be applied in future production.In order to explore the immune efficacy of Edwardsiella Tarda Ghosts(ETG) vaccine for Oreochromis niloticus. In this study,we firstly constructed plasmid vector having gene E of PhiX174 phage lysis,edwardsiella tarda ghost vaccine prepared by high-temperature-induced. The use of intraperitoneal injection and oral immune Oreochromis niloticus, respectively.Collected serum, head kidney, spleen regularly.The parameters evaluated included the specific IgM antibody titer, acid phosphatase(ACP), alkaline phosphatase(AKP) and superoxide dismutase(SOD) three kinds of enzymatic activity and the genes expression of IL-1, TNF, IFN, Caspase3 in the spleens and head kidney in head-kindney and spleen and the immunologic potency(relative percent survival,RPS) of edwardsiella tarda ghosts(ETG) and Formalin killed cell(FKC).The immune the specific IgM level were significantly increased, and ETG group and FKC groups antibody levels were significantly higher than control group(P <0.01),their antibody levels were not significantly different statistically,But immunity for 21 days and 28 days immunity,ETG group antibody levels were significantly higher than FKC groups(P <0.05).Enzyme activity results confirmedthat ETG groups and FKC groups there were no significant difference acid phosphatase vaccine group and Alkaline Phosphatase,But immune immunity 21 and 28 days,The SOD of ETG vaccine groups were significant higher than FKC vaccine groups(P <0.05).Real-time Fluorescence quantitative PCR results show ETG injection group the relative expression of IL-1 in head kidney was highly significant than control group(P <0.01),But immunization 28 days, ETG group IL-1, IFN, TNF, Caspase3 expression levels in head kidney and Caspase3 expression levels in spleen were higher than in FKC groups, were significant highly than control group(P<0.01). The relative protective survival of ETG by intraperitoneal injection and oral administration were 79%、77%, higher than FKC’s 62%、60%.ETG group and FKC group were significant higher than control group(P <0.05).Based on the above, Edwardsiella bacteria ghosts(ETG) in oral immune way can cause stronger immune response than in intraperitoneal injection way.Bacteria ghost are good candidate vaccine in preventing edwardsiella tarda disease.