SEQUENCE OF THE GENE CODING FOR THE NEUROTOXIN OF CLOSTRIDIUM-BOTULINUM TYPE-A ASSOCIATED WITH INFANT BOTULISM - COMPARISON WITH OTHER CLOSTRIDIAL NEUROTOXINS

The neurotoxin gene from a strain of Clostridium botulinum type A caus ing infant botulism was cloned as a series of overlapping polymerase c hain reaction (PCR) fragments generated using primers designed to cons erved regions of published botulinal toxin (BoNT) sequences. Translati on of the nucleotide sequence derived from cloned PCR fragments demons trated that the toxin gene encodes a protein of 1,296 amino acid resid ues. Comparative alignment of the derived infant BoNT/A sequence with those of other published neurotoxins revealed highest sequence related ness with BoNT/A of classical food-borne botulism. The sequence identi ty between infant and classical BoNT/A was 94.9% for the light chain ( corresponding to 23 amino acid changes) and 87.1% for the heavy chain (corresponding to 109 amino acid changes).