Cross-protective effect of the Cp39 adhesive proteins against avian Pasteurella multicida in mice

Abstract:

Abstract：[Objective] We evaluated the cross-protective effect of a 39-kDa adhesive protein (Cp39), recombinant adhesive protein (rCp39), and capsular proteins from in vitro and in vivo grown avian P. multocida in mice. [Methods] The Cp39 was purified by electroelution from capsular proteins of in vivo grown strain C48-3. The rCp39 was expressed in E. coli B21 as a soluble protein by IPTG inducing, and purified with pMALTM protein fusion and purification system. Mice of each group were subcutaneously immunized twice with 100μg of rCp39, Cp39 or capsular proteins from in vivo or in vitro grown strain C48-3 with in complete or incomplete Freund adjuvant at 2-week intervals. Five mice of each group were challenged with 100 LD50 of avian P. multocida strain C48-3 or rabbit P. multocida strain C51-3 two weeks after the second immunization, while the antibody response specific for rCp39 was determined by ELISA. [Results] SDS-PAGE indicated that the Cp39 protein was expressed in vitro and in vivo grown P. multocida. Mice immunized with rCp39, native Cp39 or capsular proteins from in vivo and in vitro grown strain C48-3 were protected completely against the challenge with the homologous strain C48-3, while 60-80% protection was demonstrated in the mice against the challenge with the heterologous strain C51-3. [Conclusion] In conclusion, rCp39 is a cross immunoprotective antigen of P. multocida capsular serogroup A strains, and might be a useful vaccine candidate against fowl cholera.