结核分枝杆菌培养滤液蛋白32的克隆表达及血清学检测

目的 构建结核分枝杆菌培养滤液蛋白32(culture filtrate protein 32,CFP32)的重组质粒,在大肠杆菌中表达并纯化重组蛋白CFP32,探讨其对结核病的诊断价值.方法 通过聚合酶链反应技术从结核分枝杆菌H37Rv株基因组中扩增出Rv0577基因,将其克隆到pMD18一T载体后,再亚克隆到表达载体pET21a,在大肠杆菌BL21(DE3)进行表达,经纯化及复性后,通过Western blot分析,并以酶联免疫吸附试验检测160例血清抗体,其中肺结核患者97例、非结核肺部疾病患者25例,正常对照38名.结果 构建了CFP32重组质粒,并在大肠杆菌中进行了高效表达,表达蛋白经SDSPAGE分析,在约相对分子质量30 000处有表达条带,镍柱纯化后的重组蛋白占总蛋白的90%以上.Western blot证实重组蛋白可以与结核患者血清特异结合.并以此蛋白进行160份血清结核抗体检测,结果敏感度为63.9%(62/97),特异度为96.8%(2/63).结论 成功构建pET21a-CFP32表达载体,并在大肠杆菌中高效表达CFP32蛋白,对其血清抗体检测证明重组的CFP32蛋白有希望成为结核病血清学诊断的有效候选者之一.

Expression and purification of CFP32 of Mycobacterium tuberculosis and its serodiagnostic analysis

OBJECTIVE: To establish a recombinant plasmid of CFP32 of Mycobacterium tuberculosis in E. coli, and to analyze its antigenicity. METHODS: Rv0577 gene was amplified by polymerase chain reaction from genome of Mycobacterium tuberculosis, and then cloned into vector pMD18-T followed by the subclon into the expression vector pET21a. Recombinant CFP32 was expressed and purified. The antigenicity of the recombinant protein was analyzed by using Western-blot. The purified recombinant CFP32 protein was used as an antigen to screen the sera of 7 pulmonary TB patients (n = 97), as well as the other pulmonary disease patients (n = 25), and the clinically healthy controls (n = 38) by ELISA. RESULTS: Recombinant plasmid of CFP32 was established, and be expressed efficiently in E. coli BL21 (DE3). The relative molecular mass of the protein was about 300,000 by SDS-PAGE analysis. The protein purified by Ni-NTA was in a purity over 90%, which was confirmed by Western-blot analysis. ELISA analysis showed its sensitivity and specificity were 63.9% (62/97) and 96.8% (2/63) respectively. CONCLUSION: The recombinant expression plasmid pET21a CFP32 has been constructed and CFP32 proteins has been successfully expressed and be purified in E. coli and, ELISA analysis has identified the recombinant CFP32 as a candidate antigen for TB serodiagnosis.