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大肠杆菌不耐热肠毒素（LT-WT）是引起儿童感染与旅游者腹泻的主要因素之一。以往的研究证明,LT-WT具有很强的粘膜免疫原性,可诱生具有免疫保护作用的中和抗体,但由于毒素本身的毒性作用阻碍其成为一种有用的菌苗。为寻找一个既无毒性又具良好免疫原性的物质用以制备菌苗,作者对大肠杆菌LT-WT、LT的点突变脱毒衍生物K63（K63是LT第63位上的丝氨酸被替换为赖氨酸后形成的定点突变体,结构更稳定,抗胰酶作用更强）和重组LT B亚单位（rLT-B）3种抗原的免疫原性作了比较。作者将定量的3种抗原分别以鼻内（in）,口服
Escherichia coli heat-labile enterotoxin (LT-WT) is one of the major causes of childhood infection and traveler’s diarrhea. Previous studies have demonstrated that LT-WT has strong mucosal immunogenicity and induces neutralizing antibodies with immunoprotective effects, but hinders its becoming a useful vaccine due to the toxic effects of toxins themselves. In order to find a non-toxic and good immunogenic substance for the preparation of bacterins, the authors degenerate the point-mutated derivative K63 of E. coli LT-WT, LT (K63 is serine at position 63 of LT is replaced by Lysine, a more stable structure, stronger antitrypsin activity) and the immunogenicity of the three LTB subunits (rLT-B). The authors quantify the three kinds of antigens in the nose (in), oral