Studies on the vaccine against infection of Pathogenic bacterium Edwardsiella tarda

首先以代表性菌株EF-1为研究对象，对不同血清型迟缓爱德华氏菌中常见的37 kDa外膜蛋白(Omp37Et)的产生条件进行了研究。从两个不同血清型的EF-L株和V-L株制备的Omp37Et免疫鳗鱼对EF-L株活细胞的感染有保护作用。由EF-L株制备的Omp37Et免疫比目鱼，可保护EF-L株和V-L株的活细胞感染。结果表明，Omp37Et是迟发性艾美耳球虫对不同血清型的共同保护性抗原。此外，免疫后的鱼体抗体效价和吞噬细胞活性均有所提高。对Omp37Et进行氨基酸序列分析，确定N-末端有14个氨基酸。比较迟发性艾美耳球虫福尔马林灭活细胞疫苗的不同给药方式，即腹腔注射、浸泡和口服给药，以注射给药的保护力最高，其次是口服和浸泡。免疫应答在血清抗体效价和吞噬细胞活性方面表现出与保护组相同的顺序。低pH和鱼消化酶的体外处理降低了福尔马林灭活细胞疫苗的抗原性。事实表明，用抗低pH或酶包被疫苗抗原，以保护抗原免受这些因素的影响。

Culture conditions for the production of the antigen, a 37 kDa outer membrane protein (Omp37Et), commonly distributed among Edwardsiella tarda strains of different serotypes was investigated using representative strain EF-1, first. Immunization of eel with purified Omp37Et prepared from 2 different serotype strains EF-l and V-l protected infection with live cells of EF-l strain. Immunization of Japanese flounder with Omp37Et prepared from EF-l strain protected infection with live cells of EF-l and V-l strains. The results indicate that the Omp37Et is the common protective antigen of E.tarda against different serotypes of E.tarda. Moreover, the immunized fish showed increase in the antibody titer and phagocyte activity. Amino acid sequeuce analysis of the Omp37Et identified 14 amino acid of N-terminal side. In the comparison of different administration methods, intraperitoneal injection, immersion and oral administration, of the formalin-killed cells vaccine of E.tarda, highest protection was resulted by injection then followed with oral administration and immersion. Immune response in the serum antibody titer and phagocyte activity showed same order as in the protection. Antigenicity of the formalin-killed cell vaccine was lowered by in vitro treatment with low pH and digestive enzymes of fish. The fact indicates that encapsulatio or coating of the vaccine antigen with anti-low pH or -enzymes to protect the antigen from the effect of those factors.