FIG. 2.

Postchallenge H2-D^b-NP tetramer-specific cells (A) Data are for tetramer-specific T cells in the lungs and spleens of individual mice vaccinated with the indicated DNAs and then challenged with 0.1 hemagglutinating unit of influenza A/HK/x31 (H3N2) at 12 days postchallenge. Lungs were harvested and processed for white blood cells in the same manner as were spleens (12). Cells were gated on CD8⁺, CD4⁻, and CD19⁻ cells and were cell surface stained for activated (CD11a^hi) NP-specific (D^b-NP tetramer⁺) cells. (B) Percentage of tetramer-positive CD8 T cells for each group. Values represent the averages and standard deviations of the results for five mice per group and are representative of the results for two independent experiments. Groups are indicated below the bars.