The progenies of specific-pathogen-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 less than 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.