Pasteurella multocida and Mannheimia haemolytica Vaccines for Bovine Respiratory Disease: A Comprehensive Review.

Bovine Respiratory Disease (BRD) is a leading cause of economic losses in the global cattle industry, with Mannheimia haemolytica and Pasteurella multocida as the primary bacterial pathogens. This review provides a comprehensive overview of vaccine research progress against these two pathogens, covering inactivated vaccines, live attenuated vaccines, subunit vaccines, DNA vaccines, recombinant vector vaccines, and outer membrane vesicle vaccines. Their immune mechanisms, protective efficacy, adjuvant applications, and field performance are discussed. Key challenges include maternal antibody interference, the increasing prevalence of M. haemolytica serotype A6 that evades current commercial vaccines, and the serotype diversity of P. multocida. Future vaccine development should focus on overcoming maternal antibody interference, enhancing cross-serotype protection, optimizing mucosal adjuvants and delivery systems, and developing multivalent vaccines covering major epidemic serotypes. Integrating reverse vaccinology, multi-epitope vaccine design, and nanotechnology holds promise for safer, more effective, and broader-spectrum next-generation vaccines.