Detection of neutralizing antibodies against α‐toxin of different Clostridium septicum strains in cell culture

Clostridium septicum , a ubiquitious organism, is the pathogen which causes the classical malignant edema after injuries. Because of its strong cytotoxic α‐toxin, infections are often lethal. To prevent losses in animals, vaccination with α‐toxoid vaccines is carried out. Quality control of the vaccines is done by a neutralization test in mice. A cytotoxin test and as an alternative method to detect neutralizing antibodies, a cytotoxin inhibition test was standardized. In the studies, α‐toxin of the C. septicum reference strain (NC 547) from the National Collection of Type Cultures was compared with α‐toxin of a field strain from an outbreak in Germany. Sera from five heterologous polyvalent and three monovalent vaccines from eight rabbit groups were available. Each vaccination had been carried out according to the procedure of the German Pharmacopoeia. In three out of the five sera of the groups vaccinated with the heterologous polyvalent vaccine, cytotoxin neutralizing antibodies were detected. High antibody titers were observed in sera of rabbits vaccinated with a vaccine of strain NC 547, lower titers in the sera of rabbits vaccinated with a vaccine of the field strain. No cytotoxin neutralizing antibodies could be found in the sera of rabbits vaccinated with the monovalent C. chauvoei vaccine. The toxins of all strains showed the same ranking of the vaccines. Vaccines which caused high antibody titers in the animals were detected by all toxins as such, as well as vaccines which had medium or low antibody inducing capacity. The results were independent of the C. septicum strain used for the production of α‐toxin.