Fig. 5.

Type I IFN receptor signaling is not required for the intrinsic adjuvanting of T cell responses against RepliVAX WN. (A) CD4⁺ T cell response. B6 or IFNAR^−/− mice were immunized with 10⁶ IU RepliVAX WN and the number of IFN-γ-secreting cells specific for the NS3₂₀₆₆ or E₆₄₁ CD4⁺ T cell epitopes were quantified by ELISPOT on days 9 and 14 as described in Materials and Methods. Results are expressed as the number of IFN-γ-secreting cells/spleen (mean ± SEM) and are compiled from 2 separate experiments (n = 10–12 mice/group). (B) CD8⁺ T cell responses to the NS4B₂₄₈₈ epitope were quantified by detection of intracellular IFN-γ by flow cytometry on day 6 as described in Methods. Results are expressed as the number of IFN-γ secreting cells/spleen (mean ± SEM) and are compiled from 2 separate experiments (n = 6–9 mice/group). (C) Representative histograms of CFSE-labeled target cells in spleens of naïve and RepliVAX WN-immunized B6 and IFNAR^−/− mice 4 days after immunization. Numbers in each histogram represent the % No-peptide targets (CFSE_low) and % NS4B₂₄₈₈ peptide-pulsed targets (CFSE_hi) for an individual animal. (D) Cytotoxic CD8⁺ T lymphocyte activity from B6 and IFNAR^−/− mice after RepliVAX WN immunization. The percentages of CFSE_low and CFSE_hi targets derived as shown in Fig. 5C, were used to calculate a % specific lysis as described previously [19]. Results are expressed as the % specific lysis (mean ± SEM) from 5 mice/group for NS4B₂₄₈₈-coated targets (* p < 0.005, ** p < 0.0001 compared to RepliVAX WN-immunized B6 mice). Naïve mice routinely exhibited < 2% specific lysis.