肠致病性大肠杆菌外膜蛋白免疫保护性研究

Protection of outer membrane proteins rabbits enteropathogenetic Escherichia coli against infection

目的：观察免疫家兔对肠致病性大肠杆菌外膜蛋白的免疫应答。方法：以提纯的兔源致病性大肠杆菌WF0305菌株的外膜蛋白（Outer membrane protein，OMP）皮下注射免疫组家兔，对照组仅注射佐剂，于免疫前及免疫后38天分别收集血清，以间接ELISA法检测血清中的抗体效价，同时用免疫血清与菌株做玻板凝集试验和保护力试验；采用MTT法检测OMP对体外脾淋巴细胞特异性增殖反应。结果：免疫组的家兔在三免后免疫血清中抗OMP的抗体效价可达1∶25600；免疫血清均能与WF0305菌株、WF0408菌株、WF0504菌株发生直接凝集反应，且效价均能达到1∶16以上，小鼠的半数保护量均在0.03-0.06ml之间。采用MTT法检测OMP对体外脾淋巴细胞特异性增殖反应，证明OMP对脾淋巴细胞的增殖有明显增强作用（P〈0.01）。结论：OMP可诱导兔对大肠杆菌的特异性体液免疫和细胞免疫应答，说明OMP具有较好的免疫原性，且对大肠杆菌感染有一定的保护力。

Objective,, To observe the immune responses against outer membrane protein（OMP） of enteropathogenic Escherichia coli. Methods：Big rabbits were immunized with OMP by S.C. injection. The antisera were collected at 0 and 38th days after the first inoclulation of the immunogen,respecitively. The antibodies against OMP were detected by both indirect ELISA and direct agglutinations on slides. Protection of rabbit antisera against different E. coli strains was included in the test. The proliferative response of spleen lymphocytes of the rabbits to OMP was observed by MTT assay. Results,, In the immunized group, the titer of antibodies to OMP reached to 1：25 600 on the 38th days after immunization; the rabbit antisera showed direct agglutinations to E. coli strains WF0305, WF0408 and WF0504. The 50% protective dose of antiserum in mice was 0. 03 - 0. 06 ml of the serum of rabbits immunized. The stimulation index of splenocytes of the immunized animals by OMP antigens was significandy higher than that of control animals（ P 〈 0. 01 ）. Conclusion：The result has showed that OMP can induced humoral and cellular immunoresponses in big rabbits. OMP seems to have a potent immunogenicity and induces protection against E. coli infection.