Plasmodium vivax antigen discovery based on alpha-helical coiled coil protein motif

PLoS One. 2014 Jun 24;9(6):e100440. doi: 10.1371/journal.pone.0100440. eCollection 2014.

Abstract

Protein α-helical coiled coil structures that elicit antibody responses, which block critical functions of medically important microorganisms, represent a means for vaccine development. By using bioinformatics algorithms, a total of 50 antigens with α-helical coiled coil motifs orthologous to Plasmodium falciparum were identified in the P. vivax genome. The peptides identified in silico were chemically synthesized; circular dichroism studies indicated partial or high α-helical content. Antigenicity was evaluated using human sera samples from malaria-endemic areas of Colombia and Papua New Guinea. Eight of these fragments were selected and used to assess immunogenicity in BALB/c mice. ELISA assays indicated strong reactivity of serum samples from individuals residing in malaria-endemic regions and sera of immunized mice, with the α-helical coiled coil structures. In addition, ex vivo production of IFN-γ by murine mononuclear cells confirmed the immunogenicity of these structures and the presence of T-cell epitopes in the peptide sequences. Moreover, sera of mice immunized with four of the eight antigens recognized native proteins on blood-stage P. vivax parasites, and antigenic cross-reactivity with three of the peptides was observed when reacted with both the P. falciparum orthologous fragments and whole parasites. Results here point to the α-helical coiled coil peptides as possible P. vivax malaria vaccine candidates as were observed for P. falciparum. Fragments selected here warrant further study in humans and non-human primate models to assess their protective efficacy as single components or assembled as hybrid linear epitopes.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Motifs*
  • Animals
  • Antibodies, Protozoan / immunology
  • Antigens, Protozoan / chemistry*
  • Antigens, Protozoan / genetics
  • Antigens, Protozoan / immunology*
  • Circular Dichroism
  • Computational Biology
  • Cross Reactions / immunology
  • Databases, Genetic
  • Epitopes, T-Lymphocyte / chemistry
  • Epitopes, T-Lymphocyte / immunology
  • Female
  • Genome, Protozoan
  • Histocompatibility Antigens Class II / immunology
  • Humans
  • Immunity, Cellular
  • Immunoglobulin G / blood
  • Immunoglobulin G / immunology
  • Mice
  • Peptides / chemistry
  • Peptides / immunology
  • Plasmodium vivax / genetics
  • Plasmodium vivax / immunology*
  • Protein Structure, Secondary*

Substances

  • Antibodies, Protozoan
  • Antigens, Protozoan
  • Epitopes, T-Lymphocyte
  • Histocompatibility Antigens Class II
  • Immunoglobulin G
  • Peptides