Immunogenicity and structural characterisation of an in vitro folded meningococcal siderophore receptor (FrpB, FetA)

Microbes Infect. 2006 Jul;8(8):2145-53. doi: 10.1016/j.micinf.2006.04.011. Epub 2006 May 24.


The iron-limitation-inducible protein FrpB of Neisseria meningitidis is an outer-membrane-localized siderophore receptor. Because of its abundance and its capacity to elicit bactericidal antibodies, it is considered a vaccine candidate. Bactericidal antibodies against FrpB are, however, type-specific. Hence, an FrpB-based vaccine should comprise several FrpB variants to be capable of providing broad protection. To facilitate the development of a meningococcal subunit vaccine, we have established a procedure to obtain large quantities of the protein in a native-like conformation. The protein was expressed without its signal sequence in Escherichia coli, where it accumulated in inclusion bodies. After in vitro folding, the protein was biochemically, biophysically and biologically characterised. Our results show that in vitro folded FrpB assembles into oligomers, presumably dimers, and that it induces high levels of bactericidal antibodies in laboratory animals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Bacterial / blood
  • Bacterial Outer Membrane Proteins / chemistry
  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Outer Membrane Proteins / immunology*
  • Bacterial Outer Membrane Proteins / isolation & purification
  • Circular Dichroism
  • Dimerization
  • Enzyme-Linked Immunosorbent Assay
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Gene Expression
  • Inclusion Bodies
  • Mice
  • Microscopy, Electron, Transmission
  • Neisseria meningitidis / immunology*
  • Protein Conformation
  • Protein Folding*
  • Receptors, Cell Surface / chemistry
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / immunology*
  • Receptors, Cell Surface / isolation & purification
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / immunology


  • Antibodies, Bacterial
  • Bacterial Outer Membrane Proteins
  • FrpB protein, bacteria
  • Receptors, Cell Surface
  • Recombinant Proteins
  • siderophore receptors