TLR5-dependent immunogenicity of a recombinant fusion protein containing an immunodominant epitope of malarial circumsporozoite protein and the FliC flagellin of Salmonella Typhimurium

Mem Inst Oswaldo Cruz. 2011 Aug:106 Suppl 1:167-71. doi: 10.1590/s0074-02762011000900021.

Abstract

Recently, we described the improved immunogenicity of new malaria vaccine candidates based on the expression of fusion proteins containing immunodominant epitopes of merozoites and Salmonella enterica serovar Typhimurium flagellin (FliC) protein as an innate immune agonist. Here, we tested whether a similar strategy, based on an immunodominant B-cell epitope from malaria sporozoites, could also generate immunogenic fusion polypeptides. A recombinant His6-tagged FliC protein containing the C-terminal repeat regions of the VK210 variant of Plasmodium vivax circumsporozoite (CS) protein was constructed. This recombinant protein was successfully expressed in Escherichia coli as soluble protein and was purified by affinity to Ni-agarose beads followed by ion exchange chromatography. A monoclonal antibody specific for the CS protein of P. vivax sporozoites (VK210) was able to recognise the purified protein. C57BL/6 mice subcutaneously immunised with the recombinant fusion protein in the absence of any conventional adjuvant developed protein-specific systemic antibody responses. However, in mice genetically deficient in expression of TLR5, this immune response was extremely low. These results extend our previous observations concerning the immunogenicity of these recombinant fusion proteins and provide evidence that the main mechanism responsible for this immune activation involves interactions with TLR5, which has not previously been demonstrated for any recombinant FliC fusion protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Protozoan / immunology
  • Epitopes, B-Lymphocyte / immunology
  • Epitopes, B-Lymphocyte / metabolism
  • Escherichia coli Proteins / immunology
  • Flagellin / immunology*
  • Flagellin / metabolism
  • Immunodominant Epitopes / immunology*
  • Immunodominant Epitopes / metabolism
  • Malaria Vaccines / immunology*
  • Malaria Vaccines / metabolism
  • Malaria, Vivax / immunology
  • Malaria, Vivax / prevention & control*
  • Mice
  • Mice, Inbred C57BL
  • Plasmodium falciparum / immunology*
  • Protozoan Proteins / immunology
  • Protozoan Proteins / metabolism
  • Recombinant Fusion Proteins / immunology*
  • Recombinant Fusion Proteins / metabolism
  • Salmonella typhimurium / immunology*
  • Salmonella typhimurium / metabolism
  • Toll-Like Receptor 5 / immunology

Substances

  • Antibodies, Protozoan
  • Epitopes, B-Lymphocyte
  • Escherichia coli Proteins
  • FliC protein, E coli
  • Immunodominant Epitopes
  • Malaria Vaccines
  • Protozoan Proteins
  • Recombinant Fusion Proteins
  • Toll-Like Receptor 5
  • Flagellin