Vascular permeability activity of botulinum C2 toxin elicited by cooperation of two dissimilar protein components

Botulinum C2 toxin has vascular permeability as well as lethal activities. Both activities are elicited by cooperation of two dissimilar protein components, designated components I and II, which individually have very low activities. The vascular permeability activity of C2 toxin, demonstrated as blueing response after intravenous injection of Evans blue, was markedly enhanced by treatment with trypsin and was abolished by neutralization with either anti-component I or II serum. Inflammatory reactions, such as edema, congestion, and hemorrhage, were found at the site of intradermal injection of trypsinized C2 toxin. No vascular permeability activity was demonstrated by the intradermal injection of the toxin of Clostridium botulinum types A through F. These results indicate that C2 toxin has a novel biological activity, which is not possessed by the neurotoxin elaborated by C. botulinum types A through F. This suggests that C2 toxin causes lethality in a different way from that of botulinum neurotoxin, which is known to inhibit the presynaptic release of acetylcholine at the neuromuscular junction.