产肠毒素大肠埃希菌CfaB亚单位的免疫原性分析

目的表达并纯化产肠毒素大肠埃希菌（Enterotoxigenic Escherichia coli，ETEC）CFA／I定居因子的CfaB亚单位，分析其免疫原性。方法将不含信号肽序列的cfaB基因克隆到pQE一30上，构建重组质粒pQE-30-cfaB并转化EcoliM15，表达融合蛋白6xHis—CfaB，将表达的蛋白纯化和复性后免疫BALB／c小鼠，制备抗CfaB的抗血清，用ELISA法检测抗血清效价。结果6×His—CfaB融合蛋白高效表达，相对分子质量为15．5kD，纯化复性后免疫小鼠所得抗血清效价为1：125000。结论成功构建了高效表达6×His-CfaB融合蛋白的重组质粒，表达的融合蛋白免疫小鼠后获得了高效价的抗血清，为进一步研制以双歧杆菌为表达系统的新型ETEC亚单位口服疫苗奠定了基础。

Immunogenicity analysis of ETEC CfaB subunit expressed in E.coli

Objective To analyze the immunogenicity of the CfaB subunit of enterotoxigenic Escherichia coli(ETEC) expressed in E.coli.Method cfaB gene without signal peptide sequence was cloned into the expression vector pQE-30 to construct a recombinant plasmid pQE-30-cfaB and expressed in E.coli M15.The purified and renatured 6×His-CfaB fusion protein was used to vaccinate BALB/c mice for preparing the specific antiserum.The titer of the antiserum was analyzed by ELISA.Result 6×His-CfaB fusion protein was highly expressed in E.coli M15.The relative mass(Mr) of the fusion protein was about 15.5 kD.The titer of the antiserum was 1:125000.Conclusion 6×His CfaB fusion protein can induce BALB/c mice to produce high level specific anti-CfaB antibody.The results may lay a foundation for developing novel Bifidobacterium-based vaccine against ETEC in future.