FIG. 1.

Priming with E1E2/MF59/CpG followed by boosting with VEE/SIN-E1E2 stimulates strong, good CD4⁺ and CD8⁺ T-cell responses. BALB/c mice (n = 10) received three intramuscular injections (1, 2, 3) at 3-week intervals with the immunogens indicated. The spleen cells were harvested at 2 weeks after the last immunization and stimulated with 10 μg/ml HCV-specific peptides for ICS and fluorescence-activated cell sorter analysis as described in Materials and Methods. Twenty-mer overlapping peptide pools for the HCV strain 1a E1 region (E1 pool) and E2 region (E2 pool) and single E2 peptides specific for CD4⁺ T cells (CD4 E2 pep) and CD8⁺ T cells (CD8 E2 pep) were used for stimulation. The data are presented as the mean total percentage of CD8⁺ IFN-γ⁺ (A, B, and C) and CD4⁺ IFN-γ⁺ (D) cells in two pools (five mice per pool). Data from one representative experiment of two performed are shown. *, P < 0.05 compared with the medium control and the PBS-immunized group.