We chose PR8-OT-I to focus the protection studies on the role of CTLs, as the MHC-I-restricted SIINFEKL peptide was the only shared epitope between the vaccine antigen and challenge virus.[54] At D6 post-infection, the frequency of IFN-γ-producing CTLs in the ADJ group were higher compared to PBS-OVA and ALU-OVA vaccinated mice (Fig 4C). This evidence concerns the gene IFNG and infection.