Defining a protective epitope on factor H binding protein, a key meningococcal virulence factor and vaccine antigen

Enrico Malito, Agnese Faleri, Paola Lo Surdo, Daniele Veggi, Giulietta Maruggi, Eva Grassi, Elena Cartocci, Isabella Bertoldi, Alessia Genovese, Laura Santini, Giacomo Romagnoli, Erica Borgogni, Sébastien Brier, Carla Lo Passo, Maria Domina, Flora Castellino, Franco Felici, Stijn van der Veen, Steven Johnson, Susan M. LeaChristoph M. Tang, Mariagrazia Pizza, Silvana Savino, Nathalie Norais, Rino Rappuoli, Matthew J. Bottomley, Vega Masignani

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98 Citations (Scopus)

Abstract

Mapping of epitopes recognized by functional monoclonal antibodies (mAbs) is essential for understanding the nature of immune responses and designing improved vaccines, therapeutics, and diagnostics. In recent years, identification of B-cell epitopes targeted by neutralizing antibodies has facilitated the design of peptide-based vaccines against highly variable pathogens like HIV, respiratory syncytial virus, and Helicobacter pylori; however, none of these products has yet progressed into clinical stages. Linear epitopes identified by conventional mapping techniques only partially reflect the immunogenic properties of the epitope in its natural conformation, thus limiting the success of this approach. To investigate antigen-antibody interactions and assess the potential of the most common epitope mapping techniques, we generated a series of mAbs against factor H binding protein (fHbp), a key virulence factor and vaccine antigen of Neisseria meningitidis. The interaction of fHbp with the bactericidalmAb 12C1was studied by various epitope mapping methods. Although a 12-residue epitope in the C terminus of fHbp was identified by both Peptide Scanning and Phage Display Library screening, other approaches, such as hydrogen/ deuterium exchange mass spectrometry (MS) and X-ray crystallography, showed that mAb 12C1 occupies an area of ~1,000 Å2on fHbp, including >20 fHbp residues distributed on both N- and C-terminal domains. Collectively, these data show that linear epitope mapping techniques provide useful but incomplete descriptions of B-cell epitopes, indicating that increased efforts to fully characterize antigen-antibody interfaces are required to understand and design effective immunogens.

Original languageEnglish
Pages (from-to)3304-3309
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume110
Issue number9
DOIs
Publication statusPublished - 26 Feb 2013
Externally publishedYes

Keywords

  • Antigen-antibody complex
  • Meningococcus
  • Structural mass spectrometry
  • Structure
  • Surface plasmon resonance

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