重组大肠杆菌外膜蛋白OmpT对小鼠免疫保护作用的研究

摘要

To evaluate the immunoprotection of the outer membrane protease T (OmpT) of Escherichia coli,the mice were immunized by prokaryotically expressed OmpT (rOmpT) with the mice immunized with inactivated vaccine strain of E.coli 308-2as positive control,and challenged by E.coli from different phylogenetic groups,respectively.In addition,the immunoresponses elicited by rOmpT shown that the antibody against OmpT reached the peak titer (1:64,000) at 14 days post-booster,which increased the phagocytic activity of phagocytes to E.coli,and the IL-4 and IFN-γ positive lymphocytes were significantly increased in the immunized groups comparing with the control group by ELISA spot assay.Moreover,approximate 60％ mice were protected in rOmpT immunized groups when challenged with the E.coli from 4 phylogenetic groups,respectively,which were about 10％ higher than that in inactivated E.coli vaccine groups.These data demonstrated that the rOmpT had the ability to provide efficient protection against E.coli infections and could be used as a promising subunit vaccine candidate.%为评价大肠杆菌(E.coli)外膜蛋白酶T(OmpT)的免疫原性及对小鼠的免疫效率,本研究将原核重组表达纯化的OmpT蛋白(rOmpT)免疫小鼠,并以灭活的E.coli 308-2全菌疫苗株作为对照组,通过检测其抗体效价、体外调理吞噬作用和细胞因子表达水平以及攻毒试验进行保护效率评价.结果表明rOmpT免疫组在二免后14d其抗体水平可以达到峰值(1:64000),并且其抗血清具有显著促进巨噬细胞对E.coli的吞噬作用;同时,重组蛋白与全菌免疫组均能够显著提高小鼠体内IL-4和IFN-γ的表达.而且重组蛋白免疫组对4个进化种系(Phylogenetic group)的E.coli攻毒的免疫保护率均为60％左右,比全菌免疫组高约10％.研究结果显示rOmpT比全菌灭活E.coli能够诱导小鼠产生更有效免疫保护作用,表明rOmpT可以作为E.coli亚单位疫苗候选蛋白.