耐甲氧西林金黄色葡萄球菌(MRSA)重组亚单位疫苗FnBPA的免疫保护作用研究

Protective effects of recombinant protein FnBPA against MRSA systemic infection in mice

目的评价耐甲氧西林金黄色葡萄球菌(MRSA)候选疫苗抗原FnBPA活性片段的免疫原性以及其在抵抗耐甲氧西林金黄色葡萄球菌感染中的免疫保护作用。方法构建pGEX-6p-2-FnBPA表达载体,经可溶表达及亲和纯化后的重组蛋白免疫Balb/c小鼠。末次免疫后的第7天,分离免疫小鼠的血清ELISA检测IgG及其亚型抗体水平,同时测定体外抗体介导的调理吞噬作用。末次免疫后的第14天,经尾静脉感染ATCC国际标准株MRSA-252,统计分析感染后各组的小鼠的生存率以及检测脾脏,肾脏的细菌定植量。结果成功构建、表达及纯化了FnBPA活性片段,重组蛋白纯度可达90%;免疫后诱导小鼠机体产生了高效价的IgG抗体,并在体外能发挥抗体介导的调理吞噬作用;在感染保护评价实验中,与对照组相比,实验组的生存率显著提高(P<0.01),并显著降低了脾脏与肾脏的细菌定植量(P<0.05)。结论耐甲氧西林金黄色葡萄球菌重组亚单位疫苗FnBPA具有良好的免疫原性和免疫保护作用,可以作为MRSA疫苗研究的重要候选抗原。

This study is aimed to evaluate the immunogenicity of the active fragment of fibronectin-binding protein A（FnBPA） and to investigate the immunoprotective efficacy in a mouse sepsis model.The active fragment of FnBPA was constructed and expressed.And Balb/c mice were immunized with the recombinant proteins.One week after the last booster,the sera were tested by ELISA for anti-recombinant protein antibodies.The immunoglobulin G（IgG） titers of mice immunized with FnBPA vaccine were in a high level.Antiserum capacities to opsonize phagocytosis were significantly greater in the FnBPA immunization group than that in control group（P〈0.001）.Then immunized mice were challenged with MRSA-252 via vein injection.We found that the mice immunized with the FnBPA exhibited greater survival than the mice immunized with alum adjuvant.Furthermore,the numbers of bacteria recovered in the spleens and kidneys of FnBPA group were significantly lower than those in the control group.These results suggested that immunization with FnBPA could induce humor immunity and provide strong immune protection against MRSA system infection in mice,and could therefore be a promising vaccine candidate against MRSA infection.