T-cell epitope mapping the PorB protein of serogroup B Neisseria meningitidis in B10 congenic strains of mice

T-cell epitope mapping the meningococcal serotype 15 PorB protein performed in this study in three congenic strains of mice with B10 genetic background revealed at least three murine T-cell epitopes (55-72, 163-180, and 226-261), located in the highly conserved putative transmembrane regions of Neisserial porins, Proliferation assays with popliteal lymph node cells derived from mice immunized with the PorB protein or with synthetic 18-mer peptides showed that epitope 163-180 immunized only in the H-2(d) haplotype, epitope 55-72 could be presented by both H-2(f) and H-2(s) molecules, while the 226-261 region covered by three overlapping peptides could be efficiently recognized in context of all three MHC class II haplotypes studied. Inhibition experiments with blocking I-A alpha- and I-E alpha-specific mAb showed that peptide 163-180 was presented by I-A(d) and peptide 244-261 was presented by both I-A(f) and I-A(s). In addition, evidence was obtained that peptide 226-243 was presented in context of H-2(d) or I-A(s) haplotypes and peptide 55-72 was presented in context of I-A(f) and I-A(s) loci. Finally, the Norwegian outer membrane vesicle vaccine, but not the purified PorB protein, could recall responses in mice immunized with synthetic peptides corresponding to the 226-261 region. Altogether, these results suggest that T-cell epitopes identified on the serotype 15 PorB protein, particularly those presented by several MHC class II molecules (e.g., 226-261), could have important implications for the development of meningococcal vaccines. (C) 1997 Academic Press.