VACCINATION OF CATTLE WITH OUTER-MEMBRANE PROTEIN-ENRICHED FRACTIONS OF PASTEURELLA-HAEMOLYTICA AND RESISTANCE AGAINST EXPERIMENTAL CHALLENGE EXPOSURE

Administration of an N-lauroylsarcosine - derived outer membrane prote in fraction of Pasteurella haemolytica Al (SCI-1) induced a protective response in calves against intrathoracic challenge exposure with the homologous serovar. Outer membrane proteins from heterologous serovars , A6 and A9, induced partial protection that was associated with their respective similarities to serovar A1 in outer membrane protein profi les derived by use of sodium dodecyl sulfate-polyacrylamide gel electr ophoresis. Calves vaccinated with scI preparations did not have detect able neutralizing antibody to P haemolytica A1 leukotoxin. Antibodies to whole-cell antigens, carbohydrate-protein subunit antigen, and SCI- 1 were associated with resistance, which indicates that protein antige ns shared among cell surface, carbohydrate-protein subunit, and SCI pr eparations are immunogenic and enhance resistance to experimental chal lenge exposure.