Immunogenicity and protective efficacy of a recombinant subunit West Nile virus vaccine in rhesus monkeys

Clin Vaccine Immunol. 2009 Sep;16(9):1332-7. doi: 10.1128/CVI.00119-09. Epub 2009 Jul 29.


The immunogenicity and protective efficacy of a recombinant subunit West Nile virus (WNV) vaccine was evaluated in rhesus macaques (Macaca mulatta). The vaccine consisted of a recombinant envelope (E) protein truncated at the C-terminal end, resulting in a polypeptide containing 80% of the N-terminal amino acids of the native WNV protein (WN-80E), mixed with an adjuvant (GPI-0100). WN-80E was produced in a Drosophila melanogaster expression system with high yield and purified by immunoaffinity chromatography using a monoclonal antibody specific for flavivirus E proteins. Groups of monkeys were vaccinated with formulations containing 1 or 25 microg of WN-80E antigen, and both humoral and cellular immunity were assessed after vaccination. The results demonstrated potent antibody responses to vaccination, as determined by both enzyme-linked immunosorbent assay and virus-neutralizing antibody assays. All vaccinated animals responded favorably, and there was little difference in response between animals immunized with 1 or 25 microg of WN-80E. Cellular immunity was determined by lymphocyte proliferation and cytokine production assays using peripheral blood mononuclear cells from vaccinated animals stimulated in vitro with WN-80E. Cell-mediated immune responses varied from animal to animal within each group. About half of the animals responded with lymphoproliferation, cytokine production, or both. Again, there was little difference in response between animals immunized with a 1- or 25-microg dose of WN-80E in the vaccine formulations. In a separate experiment, groups of monkeys were immunized with the WN-80E/GPI-0100 vaccine or an adjuvant-only control formulation. Animals were then challenged by inoculation of wild-type WNV, and the level of viremia in each animal was monitored daily for 10 days. The results showed that whereas all animals in the control group had detectable viremia for at least 3 days after challenge, all of the vaccinated animals were negative on all days after challenge. Thus, the WN-80E vaccine was 100% efficacious in protecting monkeys against infection with WNV.

Publication types

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

MeSH terms

  • Animals
  • Antibodies, Viral / blood
  • Cell Culture Techniques
  • Cell Line
  • Cell Proliferation
  • Cytokines / metabolism
  • Drosophila melanogaster
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Humans
  • Leukocytes, Mononuclear / immunology
  • Macaca mulatta
  • Male
  • Neutralization Tests
  • Vaccines, Subunit / immunology
  • Vaccines, Synthetic / immunology
  • Viral Envelope Proteins / immunology
  • Viremia / prevention & control
  • West Nile Fever / prevention & control
  • West Nile Virus Vaccines / immunology*


  • Antibodies, Viral
  • Cytokines
  • Vaccines, Subunit
  • Vaccines, Synthetic
  • Viral Envelope Proteins
  • West Nile Virus Vaccines