Fig 5.

Identification of antigen and peptide epitopes responsible for the CD8⁺ T cell response. (A) Frequency of CD8⁺ IFN-γ⁺ T cells in response to gp64 stimulation. (B) Frequencies of IFN-γ⁺ T cells responding to different peptides. (C) Frequencies of granzyme B (GrB)-expressing cells responding to different peptides. Mice (n = 6 for each time point) were immunized as described in the legend of Fig. 4, and splenocytes were harvested at day 0 or 21 and stimulated with purified gp64 for intracellular cytokine staining analysis of the frequency of CD8⁺ IFN-γ⁺ T cells. Alternatively, splenocytes were stimulated with putative gp64 epitopes for ELISPOT analysis of IFN-γ and granzyme B-expressing cells. MHC class I epitopes of the firefly luciferase (Luc) and nucleoprotein (NP) of AIV served as the positive and irrelevant controls, respectively. Statistical comparisons were performed by one-way ANOVA.