Fig. 1. vaccine design and in vitro characteristics.

a Schematic of YF17D and YF17D-vectored Ebola vaccine candidate (YF-EBO). EBOV GP was inserted into the E/NS1 intergenic region as translational fusion within the YF17D polyprotein inserted in the endoplasmic reticulum (gray). To cope with topological constraints of the fold of both EBOV GP antigen and the polyprotein of the YF17D vector, one extra transmembrane domain (derived from the West Nile virus E protein; light yellow) was added to the C-terminal cytoplasmic domain of the full-length EBOV GP protein. Arrows indicate protease cleavage sites. b Representative images of plaque phenotypes from YF17D and YF-EBO on BHK-21J cells, fixed 6 days post-infection. c Growth kinetics of YF17D and YF-EBO. BHK-21J cells were infected at a multiplicity of infection (MOI) of 0.01 and virus yields were quantified over time by virus titration on BHK-21J cells. Error bars indicate SEM (n = 5) and dashed line represents limit of detection (LOD). d Antigenicity of YF-EBO: confocal immunofluorescent images of BHK-21J cells 2 days post-infection with YF-EBO, staining for YF17D (green) and EBOV GP antigen (red) (nuclei stained with DAPI, blue). Scale bar, 25 μm.