肠毒素性大肠杆菌mSTⅠ-linker-LTB融合蛋白基因工程菌的构建及免疫保护试验

用分子生物学方法拼接成肠毒素性大肠杆菌(ETEC)mSTⅠ-linker-LTB融合基因，并定向克隆到pET32a(+)中，转化宿主菌BL21（DE3）。重组菌经1mM IPTG诱导，在30℃下，5h时表达产物（分子量约为37KD）达到高峰，表达量约占菌体总蛋白30%。表达产物主要存在包涵体中，经Western blot鉴定呈阳性。乳鼠胃内接种试验证明,融合蛋白无野生型STⅠ的生物毒性。将融合蛋白与矿物油乳化后免疫ICR小鼠，对K88、K99、987P和F41的保护率分别为83.3%、100%、66.7%和66.7%。

Construction of Recombinant Strain Expressing mSTⅠ-linker-LTB Fused Protein of Enterotoxigenic Esherichia coli and Its Immuonoprotection Test

The fused gene of Enterotoxigenic Esherichia coli mSTⅠ-linker-LTB was construction and was cloned into plasmid pET32a(+).The recombinatant plamsid was transformed into the expression host strain E.coli BL21（DE3）. After 5 hour induced by 1mM IPTG at 30℃, the fusion protein which molecular weight was about 37K was at the highest level. Its content was about 30% of that of total bacterial proteins. The fusion protein was mainly in inbody and was positive by Western blot. It was no the biological toxicity of the native STI demonstrated by the Suckling Mouse Assay. The purified recombinant protein emulsificated with mineral oil offered ICR mouse 83.3%、100%、66.7% and 66.7% protection against the challenge of Enterotoxigenic Esherichia coli K88、K99、987P and F41,respectively.