Evaluation of the safety and immunogenicity in rhesus monkeys of a recombinant malaria vaccine for Plasmodium vivax with a synthetic Toll-like receptor 4 agonist formulated in an emulsion

Infect Immun. 2011 Sep;79(9):3492-500. doi: 10.1128/IAI.05257-11. Epub 2011 Jun 20.

Abstract

Plasmodium vivax is the major cause of malaria outside sub-Saharan Africa and inflicts debilitating morbidity and consequent economic impacts in developing countries. In order to produce a P. vivax vaccine for global use, we have previously reported the development of a novel chimeric recombinant protein, VMP001, based on the circumsporozoite protein (CSP) of P. vivax. Very few adjuvant formulations are currently available for human use. Our interest is to evaluate second-generation vaccine formulations to identify novel combinations of adjuvants capable of inducing strong, long-lasting immune responses. In this study rhesus monkeys were immunized intramuscularly three times with VMP001 in combination with a stable emulsion (SE) or a synthetic Toll-like receptor 4 (TLR4) agonist (glucopyranosyl lipid A [GLA]) in SE (GLA-SE). Sera and peripheral blood mononuclear cells (PBMCs) were tested for the presence of antigen-specific humoral and cellular responses, respectively. All groups of monkeys generated high titers of anti-P. vivax IgG antibodies, as detected by enzyme-linked immunosorbent assays (ELISAs) and immunofluorescence assays. In addition, all groups generated a cellular immune response characterized by antigen-specific CD4(+) T cells secreting predominantly interleukin-2 (IL-2) and lesser amounts of tumor necrosis factor (TNF). We conclude that the combination of VMP001 and GLA-SE is safe and immunogenic in monkeys and may serve as a potential second-generation vaccine candidate against P. vivax malaria.

Publication types

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

MeSH terms

  • Adjuvants, Immunologic
  • Animals
  • Antigens, Protozoan / immunology
  • CD4-Positive T-Lymphocytes / immunology
  • CD8-Positive T-Lymphocytes
  • Emulsions
  • Enzyme-Linked Immunosorbent Assay
  • Fluorescent Antibody Technique
  • Immunoglobulin G / blood
  • Interferon-gamma / biosynthesis
  • Interleukin-2 / biosynthesis
  • Interleukin-2 / metabolism
  • Lipid A / immunology
  • Macaca mulatta
  • Malaria Vaccines / immunology*
  • Malaria, Vivax / immunology
  • Malaria, Vivax / prevention & control*
  • Plasmodium vivax / immunology*
  • Protozoan Proteins / immunology
  • Toll-Like Receptor 4 / agonists*
  • Toll-Like Receptor 4 / immunology
  • Tumor Necrosis Factor-alpha / biosynthesis
  • Vaccines, Synthetic / immunology

Substances

  • Adjuvants, Immunologic
  • Antigens, Protozoan
  • Emulsions
  • Immunoglobulin G
  • Interleukin-2
  • Lipid A
  • Malaria Vaccines
  • Protozoan Proteins
  • Toll-Like Receptor 4
  • Tumor Necrosis Factor-alpha
  • Vaccines, Synthetic
  • circumsporozoite protein, Protozoan
  • Interferon-gamma