Evaluation of Bordetella bronchiseptica vaccines in specific-pathogen-free piglets with bacterial cell surface antigens in enzyme-linked immunosorbent assay

Abstract

The progenies of specific-free sows which had been immunized with Bordetella bronchiseptica vaccines of various origin before parturition were challenged intranasally with B. bronchiseptica within 5 days of birth. Sera of piglets were taken weekly and investigated by enzyme-linked immunosorbent assay against a mixture of B. bronchiseptica cell surface antigens containing curled fibers and fimbriae, lipopolysaccharide, and a mixture of proteins mostly derived from the outer membrane. The serological response to this antigenic mixture was paradoxical; the highest titers were obtained with the least effective vaccines. Antibodies which did relate to protection were oriented against the outer-membrane-derived proteins, one of which, of 68,000 molecular weight, appeared to be particularly important for two reasons. First, its concentration within the antigenic mixture was dependent upon cultural conditions; of all the proteins present in virulent strains, it was the first to disappear upon modulation. Second, it was absent from a strain which was unable to induce atrophic rhinitis in specific-pathogen-free piglets. Although all vaccines tested had some beneficial effect on the various clinical manifestations of the disease, only two vaccines were effective (P < 0.001) in the prevention of nasal pathological changes. These two vaccines also stimulated the highest titers against the 68,000-molecular-weight protein. A mouse protection test utilizing a lethal intraperitoneal challenge failed to monitor the efficacy of vaccines for protection against atrophic rhinitis.