Ebola virus-like particle-based vaccine protects nonhuman primates against lethal Ebola virus challenge

Background. Currently, there are no licensed vaccines or therapeutics for the prevention or treatment of infection by the highly lethal filoviruses, Ebola virus (EBOV) and Marburg virus (MARV), in humans. We previously had demonstrated the protective efficacy of virus-like particle (VLP)-based vaccines against EBOV and MARV infection in rodents. Methods. To determine the efficacy of vaccination with Ebola VLPs (eVLPs) in nonhuman primates, we vaccinated cynomolgus macaques with eVLPs containing EBOV glycoprotein (GP), nucleoprotein (NP), and VP40 matrix protein and challenged the macaques with 1000 pfu of EBOV. Results. Serum samples from the eVLP-vaccinated nonhuman primates demonstrated EBOV-specific antibody titers, as measured by enzyme-linked immunosorbent assay, complement-mediated lysis assay, and antibody-dependent cell-mediated cytotoxicity assay. CD44⁺ T cells from eVLP-vaccinated macaques but not from a naive macaque responded with vigorous production of tumor necrosis factor-a after EBOV-peptide stimulation. All 5 eVLP-vaccinated monkeys survived challenge without clinical or laboratory signs of EBOV infection, whereas the control animal died of infection. Conclusion. On the basis of safety and efficacy, eVLPs represent a promising filovirus vaccine for use in humans.