Identification and characterization of a protective antigen, PlpB of bovine Pasteurella multocida strain LZ-PM.

The Pasteurella multocida lipoprotein B (PlpB) was cloned from Pasteurella multocida (P. multocida) strain LZ-PM (serotype A) and expressed in Escherichia coli (E. coli). Sequence analysis showed that PlpB from different strains of P. multocida exhibited 80.8-99.4% sequence identity to each other, suggesting that PlpB might serve as a cross-protective antigen. The purified PCR product of PlpB gene consisting of 831 base pairs was inserted into the pET-32a (+) plasmid, and then transferred into E. coli. The protective immunity conferred by recombinant PlpB (rPlpB) on mice was evaluated. The results showed that mice immunized with 200 μg of purified rPlpB were protected (60% survival rate) against challenge infection with 1 MLD of P. multocida strain LZ-PM. In conclusion, our data indicated that the PlpB protein may be a potential target as a candidate subunit vaccine for P. multocida infection.