Characterization of Clostridium butyricum neurotoxin associated with food-borne botulism

The neurotoxin of Clostridium butyricum strain LCL155 (BuNT/LCL155) associated with type E food-borne botulism showed antigenic and biological properties different from those of C. botulinum type E (BoNT/E) and C. butyricum strain BL5262 (BuNT/BL5262). The specific toxicity of BuNT/LCL155 was found to be about 10% those of BoNT/E and BuNT/BL5262. Immunological analysis with monoclonal antibodies against BoNT/E showed that the heavy chain of BuNT/LCL155 differs partially from those of BoNT/E and BuNT/BL5262. Binding experiments with rat brain synaptic membrane revealed that BuNT/LCL155 possesses a binding activity lower than either BoNT/E or BuNT/BL5262. There was no difference in the catalytic activity of the three neurotoxins, which had been determined with a recombinant of the intracellular target protein SNAP-25. These data suggest that the BuNT/LCL155 shares the receptor-recognition site structurally different from BoNT/E and BuNT/BL5262, perhaps causing a decreased specific toxicity.