Immunological characterization of Clostridium butyricum neurotoxin and its trypsin-induced fragment by use of monoclonal antibodies against Clostridium botulinum type E neurotoxin.

We examined the reactivities of Clostridium butyricum neurotoxin to nine monoclonal antibodies against Clostridium botulinum type E neurotoxin which recognize the light chain or the amino-terminal half (H-1 fragment) or the carboxyl-terminal half (H-2 fragment) of the heavy chain of botulinum neurotoxin. Butyricum neurotoxin and its derived chains did not react to two of four monoclonal antibodies recognizing the light chain, one of three recognizing the H-1 fragment, and one of two recognizing the H-2 fragment. The results indicate that the immunological difference between the two neurotoxins is not attributable to a particular portion of the toxin molecule. The fragment of butyricum neurotoxin obtained by prolonged tryptic treatment was found to comprise the light chain and H-1 fragment linked together by a disulfide bond.