IMMUNOLOGICAL AND FUNCTIONAL COMPARISON BETWEEN CLOSTRIDIUM-PERFRINGENS IOTA-TOXIN, CLOSTRIDIUM-SPIROFORME TOXIN, AND ANTHRAX TOXINS

Clostridian perfringens iota and C. spiroforme toxins consist of two s eparate proteins. One is the binding component and the other the enzym atic component. The two toxins secreted by Bacillus anthracis are comp osed of binary combinations of three proteins: protective antigen, let hal factor, and edema factor. As shown by Western blotting and ELISA, the binding component of anthrax toxin shares common epitopes with tha t of iota toxin and C. spiroforme toxin which are closely related immu nologically. However, no functional complementation was observed betwe en iota toxin and anthrax toxin components. The binding components can form toxins active on macrophages only in combination with their resp ective enzymatic components. Agents which prevent acidification of end osomes do not have the same effects on anthrax toxin activity as they do on iota and C. spiroforme toxins. Therefore, the mechanisms of entr y into the cells are presumably different. Since the binding component s of anthrax toxins and iota toxin share a conserved putative transloc ation domain, these binding components could have a common mode of ins ertion into the cell membranes.