Epitope mapping the Fim2 and Fim3 proteins of Bordetella pertussis with sera from patients infected with or vaccinated against whooping cough.

Antibody-binding epitopes on the Fim2 and Fim3 proteins of Bordetella pertussis, which have been associated with the induction of protective antibody, were located using sera from 12 patients with whooping cough and 4 vaccinated children. Fifteen epitopes were identified on both Fim2 and Fim3. In each case 9 were recognised by serum antibody from 11 or more infected patients. Epitopes associated with the highest IgG activity were not the same as those associated with the highest IgA activity. None of the vaccinated patients had detectable IgA. Most epitopes showed little or no evidence of serotype-specific responses, suggesting this is largely directed towards conformational epitopes. The reactivity of all but two epitopes was confirmed in an ELISA with patients' sera in which epitopes were re-synthesised as free soluble peptides. The short linear epitopes described may therefore be useful in the development of serodiagnostic assays but are unlikely vaccine candidates.