Gilligan P H, Brown J C, Robertson D C
Infect Immun. 1983 Nov;42(2):683-91. doi: 10.1128/iai.42.2.683-691.1983.
The antigenic relationships between heat-labile enterotoxin (LT) produced by a human strain of enterotoxigenic Escherichia coli (strain 286C2) and cholera toxin (CT) were examined by using antisera raised against LT and CT and specific antisera prepared against each subunit of both enterotoxins. Double immunodiffusion analysis revealed reactions of partial identity between the A subunits of LT and CT, as well as between the B subunits. Rabbit antisera raised against LT subunit A reacted with only subunit A, whereas rabbits immunized with LT subunit B produced antibodies which reacted with only subunit B. A high degree of CT neutralization was observed with antisera raised against LT. Data from neutralization assays with specific antisera to each enterotoxin showed that LT was more effectively neutralized by homologous anti-LT than CT (3.7-fold); however, anti-CT was only slightly more effective in neutralization of homologous CT compared with LT (1.9-fold). In contrast, antisera raised against the B subunit of CT (choleragenoid) exhibited significantly higher neutralization activity against CT than LT (5.8-fold); however, the amount of CT neutralized by anticholeragenoid was less (4.1-fold) than anti-CT. These results suggested that anti-CT serum contained neutralizing antibodies reactive with a shared determinant formed by interaction of the A and B subunits, whereas anti-LT and anti-choleragenoid sera did not. Sensitive solid-phase radioimmunoassays were developed to examine the affinity and degree of specificity involved in homologous and heterologous antigen-antibody interactions between LT, CT, their subunits, and specific antibodies. Only unlabeled LT competed with radiolabeled LT in polystyrene tubes coated with anti-LT, and only unlabeled CT competed with radiolabeled CT in tubes coated with anti-CT. However, when radiolabeled CT was incubated in tubes coated with anti-LT, competitive inhibition responses were observed with both unlabeled toxins. When radiolabeled LT was incubated with tubes coated with anti-CT, competitive inhibition responses were observed with both unlabeled toxins. Similar competitive inhibition responses were observed with the A subunits of LT and CT and with the B subunits using antisera specific for the subunits of each enterotoxin. Double immunodiffusion analysis and radioimmunoassay data supported the presence of unique and shared immunodeterminants in each subunit.
利用针对热不稳定肠毒素（LT）和霍乱毒素（CT）产生的抗血清以及针对两种肠毒素各亚基制备的特异性抗血清，检测了产肠毒素大肠杆菌人源菌株（286C2株）产生的热不稳定肠毒素与霍乱毒素之间的抗原关系。双向免疫扩散分析显示，LT和CT的A亚基之间以及B亚基之间存在部分相同的反应。针对LT亚基A产生的兔抗血清仅与亚基A反应，而用LT亚基B免疫的兔子产生的抗体仅与亚基B反应。观察到用针对LT产生的抗血清对CT有高度的中和作用。用针对每种肠毒素的特异性抗血清进行中和试验的数据表明，LT被同源抗LT中和的效果比CT更有效（3.7倍）；然而，抗CT在中和同源CT方面仅比LT略有效（1.9倍）。相比之下，针对CT B亚基（类霍乱原）产生的抗血清对CT的中和活性比对LT高得多（5.8倍）；然而，类霍乱原中和的CT量比抗CT少（4.1倍）。这些结果表明，抗CT血清含有与由A和B亚基相互作用形成的共同决定簇反应的中和抗体，而抗LT和抗类霍乱原血清则没有。开发了灵敏的固相放射免疫测定法，以检测LT、CT及其亚基与特异性抗体之间同源和异源抗原-抗体相互作用所涉及的亲和力和特异性程度。在包被抗LT的聚苯乙烯管中，只有未标记的LT与放射性标记的LT竞争，在包被抗CT的管中，只有未标记的CT与放射性标记的CT竞争。然而，当放射性标记的CT在包被抗LT的管中孵育时，两种未标记的毒素都观察到竞争抑制反应。当放射性标记的LT与包被抗CT的管孵育时，两种未标记的毒素也观察到竞争抑制反应。使用针对每种肠毒素亚基的特异性抗血清，在LT和CT的A亚基以及B亚基上也观察到类似的竞争抑制反应。双向免疫扩散分析和放射免疫测定数据支持每个亚基中存在独特和共同的免疫决定簇。
