TLR3 signaling induces long-lasting effector/memory CD8⁺ T cells in the absence of CD4⁺ T-cell help. (A-B) C57BL/6 mice were left untreated or were immunized by a single intravenous injection of BOVAp with poly(I:C) or anti-CD40 mAb. (A) Kinetics of the OVA_257-264–specific CD8⁺ T-cell primary response. At various times after priming, OVA_257-264–specific (OVATetr⁺) CD8⁺ T cells were quantified in the spleen by tetramer staining. Results are expressed as means ± SEM for 5 to 7 mice, tested in 2 independent experiments. (B) Specific CTL response analyzed in the spleen by in vivo killing assay at 1 week, and 2 and 4 months after priming. Data are representative of 2 independent experiments. (C) Restimulation of the CTL memory response by CyaA-OVA. C57BL/6 mice were left untreated or received an injection (intravenously) of BOVAp with poly(I:C) or anti-CD40 mAb, and, 25 days later, mice remained untreated or received an intravenous injection of CyaA-OVA. The percentage of OVATetr⁺ CD8⁺ T cells was quantified in the spleen at various times after the second injection. Results are expressed as means ± SEM for 6 mice, tested in 2 independent experiments. (D) Restimulation by CyaA-OVA of the CTL memory response in MHC-IIko mice. C57BL/6 or MHC-IIko mice were left untreated or received an intravenous injection of BOVAp with poly(I:C), and, 25 days later, mice remained untreated or received a second intravenous injection of CyaA-OVA or of BOVAp with poly(I:C). The percentage of OVATetr⁺ CD8⁺ T cells was quantified in the spleen on day 7 after the second injection. Two-tailed unpaired t test with the Welch correction was used to analyze the results presented in panel D. Data are representative of 2 independent experiments.