【摘要】 利用基因突变技术 ,将形成ST1分子内二硫键的半胱氨酸碱基进行突变 ,使ST1失去本身毒性 ,进而将其与含有LTB基因的pET₂ 8b（+）连接 ,转化至受体菌BL2 1（DE3）中 ,重组菌株BL2 1（DE3） （pXST3LTB）经IPTG诱导后 ,其表达产物免疫的小鼠能够抵抗大肠杆菌强毒菌的攻击并且消除了ST1的毒性 ,表明构建的工程菌株BL2 1（DE3） （pXST3LTB）可作为预防幼畜大肠杆菌性腹泻基因工程菌苗的候选菌株。更多还原

【Abstract】 With gene mutation technology, the mutated ST1 gene was acquired. Then the fusion gene ST1-LTB was constructed and inserted into an expression pET-28b(+).The recombinant plasmid pXST3LTB carried fusion gene ST1-LTB was transformed into E coli BL21(DE3)and the recombinant strain BL21(DE3)(pXST3LTB) was abtained. The recombinant strain BL21(DE3)(pXST3LTB) could produce ST1-LTB fusion protein after recombinant strain was inducted by IPTG and the fusion protein lost its activity as a toxin completely. The expressed ST1-LTB fusion protein could produce antibodies that were able to neutralize the biological activity of the native ST1 enterotoxin in the suckling mouse assay. Hence the recombinant strain BL21(DE3)(pXST3LTB) can be used as vaccine candidate strain.更多还原