Although two vaccines for Zaire ebolavirus (EBOV) have been licensed and deployed successfully to combat recurring outbreaks of Ebolavirus Disease in West Africa, there are no vaccines for two other highly pathogenic members of the Filoviridae, Sudan ebolavirus (SUDV) and Marburg marburgvirus (MARV). The results described herein document the immunogenicity and protective efficacy in cynomolgus macaques of a single-vial, thermostabilized (lyophilized) monovalent (SUDV) and bivalent (SUDV & MARV) protein vaccines consisting of recombinant glycoproteins (GP) formulated with a clinical-grade oil-in-water nanoemulsion adjuvant (CoVaccine HT™). Lyophilized formulations of the vaccines were reconstituted with Water for Injection and used to immunize groups of cynomolgus macaques before challenge with a lethal dose of a human SUDV or MARV isolate. Sera collected after each of the three immunizations showed near maximal GP-binding IgG concentrations starting as early as the second dose. Most importantly, the vaccine candidates (monovalent or bivalent) provided 100% protection against severe and lethal filovirus disease after either SUDV or MARV infection. Although mild, subclinical infection was observed in a few macaques, all vaccinated animals remained healthy and survived the filovirus challenge. These results demonstrate the value that thermostabilized protein vaccines could provide for addressing an important gap in preparedness for future filovirus outbreaks.
Keywords: CoVaccine HT; Cynomolgus macaques; Marburg virus; Recombinant protein subunit; Sudan ebolavirus; Thermostabilized vaccine.
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