Advances in Pasteurella multocida Vaccine Development: From Conventional to Next-Generation Strategies.

Pasteurella multocida is a Gram-negative bacterium causing significant livestock diseases, like fowl cholera and hemorrhagic septicemia in cattle, and wound infection in humans. Classified into four subspecies and five capsular serotypes, it possesses multiple virulence factors, including capsular polysaccharides (CPSs), lipopolysaccharides (LPSs), outer membrane proteins (OMPs), iron acquisition proteins, and toxins that serve as vaccine targets. Antimicrobial treatment is challenging, so vaccination is key. Commercial vaccines include killed and live attenuated types, which are commonly used, though they have intrinsic problems. Advanced vaccines like recombinant subunit and DNA vaccines are emerging. Subunit vaccines targeting OMPs (OmpH, OmpA, PlpE, VacJ, and PmSLP) and recombinant Pasteurella multocida toxin (rPMT) show high efficacy in animal models, and their recombinant proteins induce strong immune responses. DNA vaccines have promise but limited use. The challenges in vaccine development are the strain diversity, short-term immunity, and inconsistent cross-protection. There is also a lack of research on recombinant and subunit vaccine development for small ruminants. Future research should focus on multivalent vaccines, optimization, including improving adjuvants and optimizing DNA vaccine delivery.