| Pasteurella multocida is the causative agent of avian pasteurellosis, which is a highly contagious disease affecting avian species. The objectives of this research are to identify and characterize the cross-protection factor (CPF) immunogen(s) from type A P. multocida.; In the first section, lipopolysaccharides from P. multocida were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blots. We found that: (1) the LPS did not contain the O-side chain suggesting that the somatic type-specificity might be located in the core-oligosaccharide region of the molecule, (2) the SDS-PAGE profiles of LPSs from in vivo and in vitro grown P. multocida were identical, (3) iron concentration in the growth medium did not change the LPS patterns in SDS-PAGE, and (4) in Western blots, convalescent-phase sera or bacterin antisera reacted weakly only with the fast moving band.; In the second section, the SDS-PAGE was used to compare the outer membrane protein (OMP) profiles of P. multocida. We found that: (1) the live avirulent vaccine strains CU and M9 expressed strain-specific OMP markers of 48 kDa and 45 kDa respectively, and (2) in vivo grown serotype A:3 (but not in vitro grown bacteria), expressed several novel high molecular weight OMPs which reacted intensely with antibodies present in convalescent-phase sera by Western blots.; In the third paper, the relationship between the iron regulated outer membrane proteins (IROMPs) and the OMPs of in vivo grown P. multocida serotype A:3 was examined. The results showed that: (1) three IROMPs with molecular masses 76 kDa, 84 kDa, and 94 kDa were expressed by bacteria grown under iron-restricted and in vivo conditions, (2) in Western blots, convalescent-phase sera contained antibodies that reacted intensely with the three IROMPs which indicated that these proteins were expressed in vivo, and (3) all three IROMPs contained epitopes that bound to {dollar}sp{lcub}59{rcub}{dollar}Fe-multocidin complex. We speculate that the IROMPs and CPF immunogen(s) may be the same molecules.; Finally, a dot immunobinding assay (DIA) was used to detect antibodies against P. multocida in turkey sera. We found that DIA was more specific and less sensitive than the enzyme-linked immunosorbent assay (ELISA). |
