FIG. 1.

IFN-γ expression-based detection of CD8⁺ T-cell responses. Groups of four BALB/c mice were inoculated with the replicon mutant C(Δ28-89)-S or live, attenuated viruses [3′Δ10847 and C(Δ28-43)] or with a formalin-inactivated TBEV vaccine (ImmunInject). One group of mice immunized with the replicon C(Δ28-89)-S or with ImmunInject was given a second injection 4 weeks after initial immunization. CD8⁺ T cells specifically recognizing TBEV-infected cells were visualized by IFN-γ staining. Intracellular IFN-γ staining was done after culturing the spleen cells from immunized mice with MHC class I⁺ BALB/c-p815 cells or mock-infected control cells. (A) Percentages of CD8⁺ T cells specifically recognizing TBEV-infected cells in individual mice. The squares represent the mean of duplicate samples obtained from individual mice; lines represent overall mean of all samples. (B) Representative set of flow cytometry data. Dot plots were generated by gating on CD3⁺ T lymphocytes. Percentages of IFN-γ⁺ cells within CD3⁺ CD8⁺ cells are indicated in the upper right quadrant.