Generation and purification of virus-like particles (VLPs) were performed as described elsewhere [19] . In brief, ZEBOV VLP VP40-GP and VLP VP40 were generated by transient transfection of HEK 293T cells with plasmids encoding ZEBOV VP40 and/or ZEBOV GP 1,2 [19] and quantitated by electronmicroscopic particle counting [26] and a DC protein assay (BioRad, Mississauga, Ontario).