A Noncytolytic α Toxin Recombinant Protein Protects Turkeys Against Clostridium septicum Challenge

SUMMARY Clostridium septicum and its associated cytolytic α toxin, along with several other clostridial species, has been implicated as the causative agent of gangrenous dermatitis. A recombinant noncytolytic C. septicum α toxin (NCAT) peptide was developed for use as a vaccine and demonstrated to be safe at concentrations as high as 1 mg/ml. NCAT, used as a purified antigen, partially purified antigen, or in combination with native antigens, was compared to salt-fractionated α toxin combined with denatured C. septicum bacteria (native) in a vaccination trial. Three-day-old poults were placed into one of five groups and received two, 0.2-ml vaccinations 5 wk apart. Subcutaneous challenge with 3.2 × 107 log phase C. septicum resulted in 78% to 95% of the vaccinated birds surviving challenge compared to 48% of sham-injected controls. By ELISA analysis on NCAT-coated plates, birds receiving vaccines containing the recombinant NCAT peptide showed significantly higher blood serum antibody concentrations than d...