酿酒酵母表达Sj23HD-HSA融合蛋白与免疫反应性分析

目的采用酵母表达技术制备日本血吸虫中国大陆株23kDa膜蛋白分子大亲水肽段（Sj23HD）与人血清白蛋白（HSA）成熟肽的融合蛋白（Sj23HD-HSA）,并分析其免疫反应性。方法应用重叠PCR方法构建编码Sj23HD-HSA融合蛋白的融合基因片段,通过TA克隆和DNA测序确定构建的融合蛋白基因序列的正确性。将融合基因定向插入酵母表达质粒pWX530中构建分泌型重组表达载体Sj23HD-HSA/pWX530。重组质粒转化酿酒酵母感受态细胞,在亮氨酸营养缺陷型培养基上筛选含重组质粒的酵母转化子菌落。对转化子酵母进行发酵培养,通过SDSPAGE分析酵母培养液上清中的蛋白成分,离子交换层析纯化培养上清中的Sj23HD-HSA蛋白成分。经免疫印迹分别与血吸虫病人、华支睾吸虫病人和健康人血清反应,确定酵母表达的Sj23HD-HSA融合蛋白的免疫反应性。结果 DNA序列分析显示,编码外分泌型Sj23HD-HSA融合蛋白的融合基因构建成功。含有Sj23HD-HSA/pWX530重组表达质粒的酵母转化子可以在非诱导条件下表达外分泌型可溶性的Sj23HD-HSA融合蛋白,其分子量大小与预期大小（73kDa）相近。免疫印迹分析结果显示,Sj23HD-HSA融合蛋白可以特异性地被血吸虫病人血清所识别,但与华支睾吸虫病人血清、健康人血清不发生反应。结论 Sj23HD-HSA融合蛋白被成功制备,并具有良好的特异性和免疫反应性,是一种有潜在价值的血吸虫病免疫诊断抗原。

Expression and characterization of recombinant Sj23HD-HSA fusion protein in Saccharomyces cerevisiae

Objectives To prepare the fusion protein of large hydrophilic domain of 23 kDa membrane protein of Schistosoma japonicum and the mature peptide of human serum albumin （Sj23HD-HSA） and investigate its immunoreactivity. Methods A fusion protein gene encoding Sj23HD-HSA fusion protein was prepared by overlapping PCR, which was confirmed by TA cloning and DNA sequencing. The fusion gene of Sj23HD-HSA was directionally subcloned into yeast expression plasmid pWX530 to construct a recombinant plasmid Sj23HD-HSA/pWX530. The transformants of Saccharomyces cerevisiae containing the recombinant plasmid Sj23HD-HSA/pWX530 were screened on leu deficient SD medium after yeast competent cells were transformed with recombinant plasmid. The excretive Sj23HD-HSA protein was expressed by culturing the yeast transformants at 30 ℃ for 1 week, and the protein component of culture supernatant was analyzed by SDS-PAGE. Sj23HD-HSA fusion protein was purified through Ion Exchange Chromatography. The immunoreactivity of recombinant Sj23HD-HSA fusion protein was determined by Western blotting with sera of schistosomiasis, clonorchiasis and healthy. Results The gene encoding the Sj23HD-HSA fusion protein was constructed successfully, which was confirmed by DNA sequencing. The yeast transformants containing plasmid Sj23HD-HSA/pWX530 could express the excretive Sj23HD-HSA fusion protein without inducing. The results of Western blotting indicated Sj23HD-HSA could be recognized by the sera of schistosomiasis,but could not be recognized by the sera of clonorchiasis and healthy respectively. Conclusions Sj23HD-HSA fusion protein with good immune reactivity is prepared successfully, which will be a potential antigen for schistosomiasis immunodiagnosis.