Fowl cholera; cross-protective turkey antisera and IgG antibodies induced with Pasteurella multocida-infected tissue bacterins

Role of outer membrane protein H (OmpH)- and OmpA-specific monoclonal antibodies from hybridoma tumors in protection of mice against Pasteurella multocida

Two major outer membrane proteins of Pasteurella multocida, designated OmpH and OmpA, were characterized and shown to be related to the families of porin and heat-modifiable proteins, respectively. The backpack hybridoma tumor system in BALB/c mice was used to continuously deliver immunoglobulin G2b (IgG2b) monoclonal antibodies (MAbs) specific for OmpH (MAb MT1) and OmpA (MAb MT4.1). MAbs were detected in serum and peritoneal lavage samples of mice bearing hybridoma tumors by an enzyme-linked immunosorbent assay and an immunoblot assay. Highly significant protection was observed in mice bearing MT1 hybridoma tumors against both intraperitoneal and intranasal challenge infections with homologous nontoxigenic P. multocida strains possessing MAb MT1-reacting epitopes, whereas the mice bearing MT4.1 hybridoma tumors were not protected. The numbers of P. multocida organisms in the lungs of mice bearing MT1 hybridoma tumors were significantly less than those in lungs of mice bearing MT4.1 hybridoma tumors at 48 h postchallenge. These results indicate that the OmpH-specific MAb inhibited proliferation of P. multocida in the lungs. MAb MT1 was unable to kill P. multocida in vitro in the presence of complement. However, an enhanced phagocytosis by polymorphonuclear cells (PMNs) was observed in mice bearing MT1 hybridoma tumors. P. multocida induced a more extensive and rapid influx of PMNs into the peritoneal cavity of mice bearing MT1 hybridoma tumors than of mice bearing MT4.1 hybridoma tumors. The results of this study demonstrate for the first time that IgG MAbs against OmpH of P. multocida are involved in the protection of mice against lethal challenge infection by means of opsonization and inhibition of proliferation of P. multocida as a result of increased influx of PMNs into the infection site.

Use of a 35.5 kDa cell membrane composition of Pasteurella multocida and an anti-idiotype antibody to induce protective immunity in leghorn chickens

Using polyacrylamide gel electrophoresis and Western blot analysis, a 35.5 kDa cell membrane composition of Pasteurella multocida ATCC 11039 was identified as a dominant epitope of the bacterium. Mice inoculated with inactivated whole bacteria produce antisera primary reactive with the 35.5 kDa component (Pm35.5) in Western blot analysis. The outer membrane component was composed primarily of protein but did have lipopolysaccharide present at 133 micrograms mg-1 protein. In challenge trials (Trial 2), groups of white leghorn chickens vaccinated with Pm35.5 or an anti-idiotypic antibody (using Pm35.5 as the original antigen) had significant difference in mortality of 3.2% and 48.3%, respectively, when compared with unvaccinated controls (99%). Mortality in a group of chickens receiving a commercially available bacterin (9.2%) was higher but not significantly different from the mortality of the Pm35.5 vaccinated group (3.2%).

Relationship between the iron regulated outer membrane proteins and the outer membrane proteins of in vivo grown Pasteurella multocida

The SDS-PAGE patterns of the outer membrane protein (OMP) extracts of Pasteurella multocida strain P1059, grown under iron-restricted, iron-replete and in vivo conditions, were examined. The results showed that the iron-regulated outer membrane proteins (IROMPs) with molecular masses of 76 kDa, 84 kDa, and 94 kDa were expressed by bacteria grown in iron-restricted media. They were also expressed by in vivo grown P. multocida. Convalescent-phase sera, obtained from turkeys which had survived pasteurellosis, contained antibodies that reacted intensly with th three IROMPs. This indicated that these proteins were expressed in vivo. Bacteria expressing the IROMPs showed greater binding to Congo Red when compared to cells not expressing IROMPs. Cells expressing the IROMPs or its OMP extracts grown in iron-restricted media also showed greater binding to 59Fe-pasteurella siderophore (multocidin) when compared to bacteria or its extracts not expressing IROMPs. Convalescent-phase sera, which contained antibodies against the IROMPs, blocked this specific 59Fe-multocidin binding to IROMPs. Autoradiography was used to determine which of these IROMPs functioned as a receptor for the iron-multocidin complex. The results suggested that these three IROMPs have specific epitopes for binding to the iron multocidin complex.