Identification of immunodominant epitopes in the filamentous hemagglutinin of Bordetella pertussis.

The filamentous hemagglutinin (FHA) of Bordetella pertussis is a principal adhesin, which plays a key role in the colonization of the upper respiratory tract. FHA is also a protective antigen, which has been incorporated in the new generation of acellular vaccines against whooping cough. The protein is synthesized as a large 367-kDa precursor, which is then processed into a 220-kDa secreted polypeptide. To optimize the use of this protein for vaccine purposes it would be helpful to define the regions encompassing immunodominant epitopes. Twelve recombinant plasmids have been generated encoding fusion proteins between fragments of the matured-secreted 220-kDa form of FHA and the vector-encoded phage MS2 polymerase. Protein extracts of the resulting recombinant clones have been tested for reactivity with sera from 20 patients convalescent from whooping cough, and two human standard sera. The results indicate the presence of an immunodominant B cell epitope in the polypeptide coded by a 1-kb DNA fragment encompassing positions 5781-6800 of the published sequence. These results suggest that the identified fragment should be conserved in the formulation of vaccines against pertussis.