Immunogenicity and protective efficacy of seven candidate vaccines boosted with recombinant proteins, whole-cell bacterins of three serotypes of Mannheimia haemolytica, and an emulsion-type adjuvant

The haemorrhagic effects observed with S6 highlight the importance of including this serotype in future vaccines. The trivalent S6 vaccine with Montanide™ ISA 206 shows promise for improved protection against diverse <i>M. haemolytica</i> strains. Further research, including challenge studies in target animals, is needed to confirm these findings and evaluate field efficacy.