Rabbit nasopharyngeal colonization byBordetella pertussis: the effects of immunization on clearance and on serum and nasal antibody levels

Abstract

SummaryTwoBordetella pertussisantigen preparations, outer membrane protein (OMP) and filamentous haemagglutinin (FHA), and a standard vaccine were used to immunize rabbits, and the effects on nasopharyngeal colonization by the organism were determined. Antibodies were measured in serum and in nasal washes by ELISA before and after challenge of the rabbits with 106bacteria of strain M2. Recoveries ofB. pertussisin nasal washes were used to assess colonization, which in controls persisted for at least 65 days. Some rabbits of all the immunized groups showed enhanced clearance, but there was no correlation between the elimination ofB. pertussisand serum antibodies to OMP, FHA, lipopolysaccharide, lymphocytosis-promoting factor or agglutinogen 3. In contrast, nasal IgA antibody to FHA showed significant inverse correlation with bacterial persistence. Such antibody was induced by the OMP preparation as well as by FHA, but to different extents depending on the immunization schedule and adjuvant used.