Identification of immunogenic, surface-exposed outer membrane proteins of Pasteurella haemolytica serotype 1

Pasteurella haemolytica serotype 1 (S1) is the bacterium most frequently re covered from the lungs of cattle that have succumbed to shipping fever pneu monia. P. haemolytica outer membrane proteins (OMPs) are important immunoge ns in the development of resistance to pneumonic pasteurellosis. The purpos e of this study was to identify the repertoire of immunogenic, surface-expo sed P. haemolytica (S1) OMPs, that could be important in the development of protective immunity. We determined surface exposure of OMPs by (1) their s usceptibility to protease treatment and (2) their ability to adsorb out ant ibodies from bovine immune sera. For a comprehensive identification of immu nogenic, surface-exposed OMPs, we used bovine antisera from calves that wer e resistant to experimental P. haemolytica challenge after (1) natural expo sure to P. haemolytica, (2) vaccination with live P. haemolytica, or (3) va ccination with P. haemolytica OMPs. We identified 21 immunogenic, surface-e xposed P. haemolytica OMPs. Most were recognized by all three immune sera. However, some were recognized by one or two of the three antisera. Our anal yses identified surface-exposed, immunogenic proteins that were not identif ied in previous studies. (C) 1999 Elsevier Science B.V. All rights reserved .