Fig. 2.

Peptide S1_526–533 is identified as the H2-D^d-restricted CD8⁺ CTL epitope. (A, B) BALB/c mice were immunized with the S1 protein twice weekly. Splenocytes were obtained and specific T-cell induction was analyzed with intracellular cytokine staining assays, using stimulation with the indicated peptides. (B) The avidity of the induced S-RBD-specific CD8⁺ T cells was analyzed with intracellular cytokine staining assays, using stimulation by graded doses of the peptides (ranging from 1 to 0.003 µM). (C) BALB/c mice were immunized with the S1 protein twice weekly. Splenocytes were obtained and specific T-cell induction was stimulated with S1_526–533 peptides. MHC restriction of the induced S-RBD-specific CD8⁺ T cells was analyzed with the intracellular cytokine staining assay after the addition of anti-H2-K^d/D^d or anti-H2-K^d mAbs. These experiments were repeated two times with similar results. Data are the mean ± SD.