Mosaic type of the nontoxic-nonhemaggulutinin component gene in Clostridium botulinum type A strain isolated from infant botulism in Japan.

The gene encoding the nontoxic-nonhemaggulutinin (NTNH) component was amplified by the PCR technique using two primer sets and the DNA template from Clostridium botulinum type A strain 7I03-H isolated from infant botulism in Japan. The nucleotide sequence revealed that the NTNH gene was composed of 1,193 amino acids with a molecular weight of 130868.08. Furthermore, the N-terminal half side and C-terminal half side of the NTNH component were similar to the NTNH component of type C and type A, respectively. These results indicate that the NTNH component gene codes the mosaic NTNH component composed of type A and type C. The hemaggulutinin gene, aha, and ORF-22 gene, orf-22a, were undetectable in the region upstream of the NTNH component gene, ant. Therefore, orf-22a is not thought to play a key role in the expression of botulinum type A progenitor toxin gene.