Immunogenicity of heterologous (Ad26-Ad35) tetravalent and homologous (Ad26) trivalent vaccine regimens and protection from MARV Angola challenge.

<p>(A-D) Cynomolgus macaques were immunized with heterologous Ad26 prime at week 0 and Ad35 boost at week 4 with a tetravalent vaccine, or a monovalent Ad26 MARV GP vaccine, or empty Ad vectors, at the doses indicated. (E-H) Cynomolgus macaques were immunized with homologous trivalent Ad26 prime at week 0 and Ad26 boost at week 4, or a monovalent Ad5 MARV GP vaccine (prime only at week 4), or empty Ad vectors, at the doses indicated. A challenge with 1000 pfu MARV Angola was given at week 8. (A+E) Kaplan-Meier representation of survival. (B+F) Clinical scoring of individual animals after lethal challenge. (C+G) Humoral immune response over time measured by MARV GP-specific ELISA. Horizontal dotted line represents the lower limit of detection. Solid lines indicate the group mean. (D+H) Cellular immune response to MARV GP peptide pool by IFNγ ELISpot. Vertical dotted lines indicate the time of boost immunization. Solid lines indicate the group mean.