Molecular variation between the α-toxins from the type strain (NCTC 8237) and clinical isolates of Clostridium perfringens associated with disease in man and animals

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Abstract
The α-toxin produced by the type strain of Clostridium perfringens (NCTC 8237) was shown to differ from the α-toxins produced by most strains of C. perfringens isolated from man and from calves with respect to reactivity with a neutralizing monoclonal antibody (DY2F5D11). The difference in antibody binding correlated with three differences in the deduced amino acid sequence (Ala174 to Asp174; Thr177 to Ala177; Ser335 to Pro335) of the α-toxins. Using octapeptides synthesized on the basis of the amino acid sequences from these regions of variability, it was shown that the Ala174 to Asp174 change had the greatest effect on reducing the binding of monoclonal antibody DY2F5D11 to the α-toxin. These differences did not affect the enzymic or toxic properties of the protein. However, the phospholipase C activity of the α-toxin produced by strain NCTC 8237 was more susceptible to inactivation by chymotrypsin. The changes in amino acid sequence did not affect the ability of a C-terminal domain vaccine, derived from the α-toxin of strain NCTC 8237, to induce protection against the α-toxin from a bovine enteric strain of C. perfringens.