The lack of TLR3 triggering decreases the ability of poly(I:C) to promote CTL responses in the absence of T-cell help. (A) C57BL/6, TLR3ko, or TLR9ko mice received a single intravenous injection of either poly(I:C) or CpG-B(DOTAP), and, various times after injection, their sera were titrated for IFN-α, IFN-β, IL-12p40, IL-6, and MIG by ELISA. Results are expressed as means ± SEM for 4 mice per group, tested in 2 independent experiments. (B) C57BL/6, TLR3ko, or TLR9ko mice were left untreated or received intravenous injections of BOVAp either alone or in combination with poly(I:C) or CpG-B(DOTAP). The specific CTL response was analyzed on day 7 by in vivo killing assay (upper panel) or tetramer staining (lower panel). (C) C57BL/6, TLR3ko, or TLR9ko mice were left untreated or were immunized intravenously with BOVAp either alone or in combination with anti-CD40 mAb. The specific CTL response was analyzed on day 7 by in vivo killing assay. Results are expressed as means ± SEM for 3 to 4 mice. (B-C) Data are representative of 3 independent experiments.