Identification and characterization of phage-displayed peptide mimetics of Neisseria meningitidis serogroup B capsular polysaccharide.

Neisseria meningitidis causes meningitis and septicemia. There is no single vaccine against all serogroup B meningococcal (MenB) strains up to now. Their capsular polysaccharide (MenB CPS) bears epitopes both cross-reacting and non-cross-reactive with human polysialic acid. A bactericidal and protective antibody mAb (13D9) recognizing a unique epitope in MenB CPS was used to screen a phage-displayed peptide library. Four peptides, able to bind mAb 13D9 in competition with MenB CPS, were identified. Immunization of mice with the phage-displayed peptides elicited anti-peptide IgG antibodies, mainly IgG(2a) for 3 of the peptides and bactericidal and protective antibody levels for one of them. Peptides specifically targeting the immune response toward epitopes found only in MenB CPS could be considered for a universal vaccine against serogroup B meningococcal strains.