Development of Targeted Therapeutic Agents for Botulism
Final rept. 25 Aug 1997-24 Jan 2001
LONDON UNIV (UNITED KINGDOM)
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The neuroparalytic symptoms of human botulism, resulting from inhibition of acetylcholine release by type A botulinum neurotoxin BoNTIA, are life threatening and last for up to 2 years. Thus, development of a fast and effective treatment for the forces exposed to this threat warrants the highest priority. Initial experiments focussed on developing an avid inhibitor of the BoNTIA protease that cleaves SNAP-25 - a SNARE essential for transmitter release. The inhibitors prepared were toxin-resistant mutants of the full-length substrate that retained ability to mediate exocytosis. This vital advance created a means of overcoming the poisoning by transfecting cultured neuroendocrine cells with these SNAP-25 genes. Importantly, the constructs encoding several non-cleavable SNAP-25s rescued exocytosis in BoNTlA-blocked cells, providing an innovative, efficient and rapid therapy for botulism which can be adopted for humans. Moreover, the observed inability of wild-type SNAP-25 to counteract the toxins action, even at 3 weeks after intoxication, revealed the amazing longevity of type A protease.