Antigenic topology of chlamydial PorB protein and identification of targets for immune neutralization of infectivity

J Immunol. 2002 May 15;168(10):5184-91. doi: 10.4049/jimmunol.168.10.5184.

Abstract

The outer membrane protein PorB is a conserved chlamydial protein that functions as a porin and is capable of eliciting neutralizing Abs. A topological antigenic map was developed using overlapping synthetic peptides representing the Chlamydia trachomatis PorB sequence and polyclonal immune sera. To identify which antigenic determinants were surface accessible, monospecific antisera were raised to the PorB peptides and were used in dot-blot and ELISA-based absorption studies with viable chlamydial elementary bodies (EBs). The ability of the surface-accessible antigenic determinants to direct neutralizing Ab responses was investigated using standardized in vitro neutralization assays. Four major antigenic clusters corresponding to Phe(34)-Leu(59) (B1-2 and B1-3), Asp(112) -Glu(145) (B2-3 and B2-4), Gly(179)-Ala(225) (B3-2 to B3-4), and Val(261)-Asn(305) (B4-4 to B5-2) were identified. Collectively, the EB absorption and dot-blot assays established that the immunoreactive PorB Ags were exposed on the surface of chlamydial EBs. Peptide-specific antisera raised to the surface-accessible Ags neutralized chlamydial infectivity and demonstrated cross-reactivity to synthetic peptides representing analogous C. pneumoniae PorB sequences. Furthermore, neutralization of chlamydial infectivity by C. trachomatis PorB antisera was inhibited by synthetic peptides representing the surface-exposed PorB antigenic determinants. These findings demonstrate that PorB Ags may be useful for development of chlamydial vaccines.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Bacterial / metabolism
  • Antigens, Bacterial / analysis*
  • Antigens, Bacterial / immunology
  • Antigens, Bacterial / metabolism
  • Bacterial Outer Membrane Proteins / analysis*
  • Bacterial Outer Membrane Proteins / immunology
  • Bacterial Outer Membrane Proteins / metabolism
  • Binding, Competitive / immunology
  • Cell Line
  • Cell Membrane / immunology
  • Cell Membrane / metabolism
  • Cell Membrane / microbiology
  • Chlamydia Infections / immunology*
  • Chlamydia Infections / microbiology
  • Chlamydia Infections / prevention & control*
  • Chlamydia trachomatis / chemistry
  • Chlamydia trachomatis / immunology*
  • Chlamydia trachomatis / metabolism
  • Cricetinae
  • Enzyme-Linked Immunosorbent Assay
  • HeLa Cells
  • Humans
  • Immune Sera / analysis
  • Immunoblotting
  • Molecular Sequence Data
  • Peptide Fragments / immunology
  • Peptide Fragments / metabolism
  • Peptide Mapping / methods*
  • Porins*

Substances

  • Antibodies, Bacterial
  • Antigens, Bacterial
  • Bacterial Outer Membrane Proteins
  • Immune Sera
  • Peptide Fragments
  • Porins
  • porin protein, Neisseria