Interestingly, the determination of IL-6 levels in plasma 8 h after infection revealed that the ablation of mDCs in CD11cDTR/GFP transgenic mice affected only moderately the induction of IL-6 ( Fig. 3B) , confirming that non-DCs contribute significantly to the Ad-elicited IL-6 response in vivo. The fact that different cell types are responsible for IFN-ab and IL-6 response to Ad may explain at least in part why viral gene expression did not inhibit the production of IL-6 in Ad3-or Ad R700-infected mice (see Fig. 1C and Fig. S2D ). In order to functionally evaluate the possible participation of pDCs to the systemic production of IFNab to Ad we also checked this response in mice depleted of pDCs. As shown in Fig. S6A and B, the injection of anti PDCA-1 antibody led to the substantial decrease of the number of splenic pDCs. Nevertheless, the production of IFN-ab was not changed in response to Ad infection (Fig. 3C) . The data collectively show that the vast majority of IFN-ab but not of IL-6 in Ad infected-mice is produced by splenic mDCs.