Lethal and vascular permeability activities of botulinum C2 toxin induced by separate injections of the two toxin...

Two components, designated I and II, of botulinum C2 toxin were injected separately into the same animal. The intravenous injection of one component at different time intervals after intravenous injection of the other component, irrespective of the sequence, was lethal to mice. When components I and II were injected intradermally into separate sites, vascular permeability increased only at the site where component II was injected. The sizes of blued areas were smaller with increased distance between the injection sites of components I and II. When one component was injected intravenously and the other intradermally, an increase in vascular permeability was induced at the intradermal site of injection of component II but not at that of component I. These results indicate that the simultaneous injection of components I and II is not always required to elicit the biological activity of C2 toxin. The vascular permeability response induced by separate injections of the two toxin components suggests that the activity of C2 toxin results from component II binding to the tissue around its injection site and component I recognizing the altered tissue.