大肠杆菌肠毒素ST_1-LT_B融合蛋白工程菌株的免疫原性研究

Immunogenicity of the Genetic Engineering Strain Expressing Escherichia coli Heat stable Enterotoxin I and Heat labile Enterotoxin B Subunit Fusion Protein

已构建的能表达大肠杆菌肠毒素ＳＴ１ＬＴＢ融合蛋白的工程菌株ＢＬ２１（ＤＥ３）（ｐＸＥＴＳＬＴ１）及其表达产物经动物试验证实没有毒性反应。用从ＩＰＴＧ诱导的工程菌中提取的包涵体或经甲醛灭活的工程菌制成抗原，免疫小鼠，结果免疫小鼠至少能抵抗１５ＭＬＤ的大肠杆菌强毒株Ｃ８３９０２（Ｋ８８ａｃ，ＳＴ＋，ＬＴ＋）的攻击。用提取的包涵体免疫家兔后，采集的血清能够中和天然ＳＴ１的毒性。这表明构建的工程菌株ＢＬ２１（ＤＥ３）（ｐＸＥＴＳＬＴ１）可以作为预防幼畜大肠杆菌性腹泻基因工程菌苗的候选株。

Fusion protein of heat stable enterotoxin I and heatlabile enterotoxin B subunit of Escherichia coli was expressed in recombinant strain BL21(DE3)(pXETSLT1),and completely lost its activity of the toxin.Mice immunized with crude inclusion bodies containing ST 1 LT B fusion protein or inactivated recombinant strain produced antibodies that were able to provide protection in a mouse model against the challenge of at least 1 5MLD dose of Escherichia coli C83902.Importantly,rabbit immunized with crude inclusion bodies containing ST 1 LT B fusion protein could produce antibodies that were able to neutralize the biological activity of native ST 1 enterotoxin in the suckling mouse assay.Hence the recombinant strain BL21(DE3)(pXETSLT1)can be used as a candidate of vaccine strain.