Relative immunogenicity and efficacy of two synthetic chimeric peptides of fimbrin as vaccinogens against nasopharyngeal colonization by nontypeable Haemophilus influenzae in the chinchilla

The OMP P5-homologous fimbriae of nontypeable Haemophilus influenzae (NTHi) are an adhesin and a virulence factor for otitis media in chinchilla models. We synthesized two peptides (LB1 and LB2) which incorporate determinants of the fimbrial subunit co-linearly synthesized with a “promiscuous” T-cell epitope from the fusion protein of measles virus. Sera obtained from immunized rabbits and chinchillas demonstrated significant reciprocal titers against both the homologous peptide and isolated fimbrial protein. Antisera also immunolabeled native fimbriae of whole unfixed NTHi. Immunization with LB1 or fimbrin resulted in elimination of NTHi from the chinchilla nasopharynx 2–3 weeks earlier than controls, respectively.