The role of CD8+T cells in host defense may be central in prevention of infection; for example, in a small cohort of cynomolgus macaques vaccinated with recombinant adenovirus 5 encoding Ebola virus glycoprotein, 4 of 5 macaques were not protected if CD8+ T cells were specifically depleted in vivo prior to Ebola challenge [52]. This evidence concerns the gene CD8A and Ebola hemorrhagic fever.