Assessment of Ebola Specific Antibody Responses in Vaccinated Macaques (128.20)

Abstract

Abstract Ebola virus (EBOV) infection causes severe disease accompanied by high mortality rates. Several vaccine platforms have shown promise in protecting against Ebola exposure; however, there are no licensed vaccines or therapies approved and available for human use. A vaccine approach utilizing Venezuelan equine encephalitis virus (VEE) replicon particles (VRP) expressing filovirus protein(s) was the first vaccine approach that provided complete protection against Marburg infection in non-human primates (NHP). We evaluated the ability of VEE replicons expressing the glycoprotein (GP), nucleoprotein (NP), VP24, VP30, VP35, and VP40 to protect against Ebola Zaire (ZEBOV) exposure in NHP by various routes of administration, intramuscular (IM) versus subcutaneous (SC). To further evaluate protective efficacy, NHP were vaccinated IM or SC with VEE replicon expressing the viral glycoprotein or expressing all six proteins. Protective efficacy was demonstrated in the both cynomolgus macaques and rhesus macaques. Enzyme-Linked ImmunoSorbent Assays (ELISA) were developed using the whole antigen or recombinant Ebola GP to assess vaccine induced immunity against EBOV. The ELISA based assay assessing humoral responses did not accurately predict protection. The protection generated by the VEE replicon expression of Ebola proteins demonstrates the efficacy of the vaccines platform and warrants further evaluation as a human use vaccine. Further studies are needed to develop accurate correlate of immunity assays.</jats:p