title: Identification of vaccine antigens using integrated proteomic analyses of surface immunogens from serogroup B Neisseria meningitidis.
abstract: Meningococcal surface proteins capable of evoking a protective immune response are candidates for inclusion in protein-based vaccines against serogroup B Neisseria meningitidis (NmB). In this study, a 2-dimensional (2-D) gel-based platform integrating surface and immune-proteomics was developed to characterize NmB surface protein antigens. The surface proteome was analyzed by differential 2-D gel electrophoresis following treatment of live bacteria with proteinase K. Alongside, proteins recognized by immune sera from mice challenged with live meningococci were detected using 2-D immunoblots. In combination, seventeen proteins were identified including the well documented antigens PorA, OpcA and factor H-binding protein, previously reported potential antigens and novel potential immunogens. Results were validated for the macrophage infectivity potentiator (MIP), a recently proposed NmB vaccine candidate. MIP-specific antisera bound to meningococci in whole-cell ELISA and facilitated opsonophagocytosis and deposition of complement factors on the surface of meningococcal isolates of different serosubtypes. Cleavage by proteinase K was confirmed in western blots and shown to occur in a fraction of the MIP expressed by meningococci suggesting transient or limited surface exposure. These observations add knowledge for the development of a protein NmB vaccine. The proteomic workflow presented here may be used for the discovery of vaccine candidates against other pathogens.
  
  
  CONCLUSIONS
  This study presents an integrated proteomic strategy to identify proteins from N. meningitidis with desirable properties (i.e. surface exposure and immunogenicity) for inclusion in subunit vaccines against bacterial meningitis. The effectiveness of the method was demonstrated by the identification of some of the major meningococcal vaccine antigens. Information was also obtained about novel potential immunogens as well as the recently described potential antigen macrophage infectivity potentiator which can be useful for its consideration as a vaccine candidate. Additionally, the proteomic strategy presented in this study provides a generic 2-D gel-based platform for the discovery of vaccine candidates against other bacterial infections.
authors.affiliation: National Institute for Biological Standards and Control, Medicine and Healthcare Products Regulatory Agency, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, United Kingdom; Centre for Molecular Microbiology and Infection, Division of Infectious Diseases, Department of Medicine, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: Nikos
authors.initials: N
authors.lastname: Tsolakos
authors.affiliation: Public Health England, Porton Down, Salisbury SP4 0JG, United Kingdom.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Brookes
authors.affiliation: Public Health England, Porton Down, Salisbury SP4 0JG, United Kingdom.
authors.forename: Stephen
authors.initials: S
authors.lastname: Taylor
authors.affiliation: Public Health England, Porton Down, Salisbury SP4 0JG, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Gorringe
authors.affiliation: Centre for Molecular Microbiology and Infection, Division of Infectious Diseases, Department of Medicine, Imperial College London, London SW7 2AZ, United Kingdom.
authors.forename: Christoph M
authors.initials: CM
authors.lastname: Tang
authors.affiliation: National Institute for Biological Standards and Control, Medicine and Healthcare Products Regulatory Agency, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, United Kingdom.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Feavers
authors.affiliation: National Institute for Biological Standards and Control, Medicine and Healthcare Products Regulatory Agency, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, United Kingdom. Electronic address: jun.wheeler@nibsc.org.
authors.forename: Jun X
authors.initials: JX
authors.lastname: Wheeler
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000302:isolation & purification / Q000378:metabolism*; D000954:Antigens, Surface / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*; D001426:Bacterial Proteins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism; D019286:Endopeptidase K / Q000494:pharmacology; D005260:Female; D008585:Meningitis, Meningococcal / Q000276:immunology*; D022401:Meningococcal Vaccines / Q000302:isolation & purification / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D038541:Neisseria meningitidis, Serogroup B / Q000737:chemistry* / Q000276:immunology* / Q000378:metabolism; D040901:Proteomics / Q000379:methods*
chemical_list: D000942:Antigens, Bacterial; D000954:Antigens, Surface; D001426:Bacterial Proteins; D022401:Meningococcal Vaccines; D019286:Endopeptidase K
keywords: Differential gel electrophoresis; Immunoproteome; Macrophage infectivity potentiator; Meningococcal vaccines; Neisseria meningitidis; Proteomics