Wilkins T, Krivan H, Stiles B, Carman R, Lyerly D
Ciba Found Symp. 1985;112:230-41. doi: 10.1002/9780470720936.ch13.
Clostridium difficile and Clostridium spiroforme have only in recent years been recognized as intestinal pathogens. They both produce toxins that are also produced by other clostridia. C. difficile toxins A and B are produced by C. sordellii and a few strains of C. perfringens whereas C. spiroforme produces the same toxins as C. perfringens Type E (iota toxin). Iota toxin activity may be the product of two proteins. Toxigenic strains of C. spiroforme and Type E produce two antigens which possess much more biological activity when administered together than when given alone. C. difficile was thought for some time to produce only a single toxin, but then the enterotoxic activity was shown to be due to a separate toxin (toxin A). This toxin increases the oral toxicity of toxin B (the main cytotoxin) and may increase the permeability of the colon. Toxin A binds to a specific receptor in hamster brush border membranes and in the membranes of rabbit erythrocytes. This receptor appears to be a glycoprotein. The receptor can be extracted from the membrane with Triton and binds to immobilized toxin A. The receptor can be extracted and used to coat plastic plates as a first phase in an ELISA assay. Another assay has been developed in which the toxin A binds to the red cells and then the erythrocytes are agglutinated with antitoxin. An even more sensitive assay consists of using rabbit erythrocyte ghosts to bind the toxin and then precipitating the ghosts with antibody to toxin A attached to latex beads. Monoclonal antibodies to toxin A also have been developed and are used in these and other assays.
艰难梭菌和螺旋形梭菌直到最近几年才被确认为肠道病原体。它们都产生毒素，而其他梭菌也能产生这些毒素。艰难梭菌毒素A和B由索氏梭菌及少数产气荚膜梭菌菌株产生，而螺旋形梭菌产生的毒素与产气荚膜梭菌E型（iota毒素）相同。Iota毒素活性可能是两种蛋白质的产物。螺旋形梭菌的产毒菌株和E型菌株产生两种抗原，这两种抗原一起给药时比单独给药时具有更强的生物活性。一段时间以来，人们认为艰难梭菌仅产生一种毒素，但后来发现其肠毒素活性是由一种单独的毒素（毒素A）引起的。这种毒素会增加毒素B（主要的细胞毒素）的口服毒性，并可能增加结肠的通透性。毒素A与仓鼠刷状缘膜和兔红细胞膜中的特定受体结合。这种受体似乎是一种糖蛋白。该受体可用Triton从膜中提取出来，并与固定化的毒素A结合。可以提取该受体并将其用于包被塑料板，作为酶联免疫吸附测定（ELISA）的第一步。已经开发出另一种检测方法，其中毒素A与红细胞结合，然后用抗毒素使红细胞凝集。一种更灵敏的检测方法是使用兔红细胞血影结合毒素，然后用附着在乳胶珠上的毒素A抗体沉淀血影。针对毒素A的单克隆抗体也已开发出来，并用于这些及其他检测方法中。
