Protection efficacy and immunogenicity of Clostridium chauvoei proteins as a subunit blackleg vaccine or an adjuvant for Clostridium perfringens epsilon toxoid

Potential application of Clostridium chauvoei proteins was studied as a subunit blackleg vaccine or a biological adjuvant for Clostridium perfringens epsilon toxoid vaccine. Extracellular and cell surface proteins were extracted from C. chauvoei culture, and their protective efficacy was evaluated by potency test in guinea pigs. In order to investigate the effect of cell surface proteins on C. perfringens epsilon toxoid immunogenicity, rabbits were inoculated subcutaneously twice with: C. perfringens type D toxoid supernatant +200 μg C. chauvoei cell surface proteins (PR-200), toxoid supernatant + 400 μg cell surface proteins (PR-400), inactivated C. perfringens type D vaccine (Vac), toxoid supernatant (Tox), or PBS. Isolation of cell surface proteins yielded about 2.5 mg/L culture protein with a sharp band at 43 kDa probably corresponding to flagellin. Potency test demonstrated the protection ability of both cellular and extracellular proteins of C. chauvoei. ELISA showed that the highest antibody titers against epsilon toxoid belonged to PR-400 and Vac groups. The effect of days post immunization on antibody response was not significant. No significant difference was observed between PR-400 and Vac, as well as PR-200 and Tox groups. Clostridium chauvoei cell surface proteins may have the potential for application as a blackleg disease vaccine and an adjuvant for clostridial toxoids.