Fig 3.

Cellular immune responses elicited with the triclade DNA vaccine against two HA-specific peptides. Intracellular cytokine staining was performed to analyze the CD8 T-cell responses against two HA-specific peptides. The percentages of activated CD8⁺ T cells that produce IFN-γ (A), IL-2 (B), and TNF-α (C) are shown. Splenocytes from mice (n = 6 per group) immunized with empty vector or mice (n = 6 per group) immunized with the triclade DNA were assessed, and immune responses were measured 10 days after the final boost. “I” stands for peptide I (IYSTVASSL); “II” stands for peptide II (LYEKVRLQL). The mean value is shown with the horizon bar. *, P = 0.01 to 0.05; **, P = 0.001 to 0.01; ***, P < 0.001.