CD8+ cellular immunity mediates rAd5 vaccine protection against Ebola virus infection of nonhuman primates

Vaccines that protect nonhuman primates from lethal Ebola virus infection have been developed, but their protective mechanisms have not been clearly delineated. Nancy Sullivan et al. now report that the protective efficacy of a recombinant Ad5-based Ebola virus vaccine relies primarily on CD8+ T cells rather than on antibodies. The findings suggest that clinical development of T cell–based vaccines against Ebola virus is warranted.