pp65-specific T-cell expansion. (A) Postvaccination levels of pp65 CD8 and CD4 T cells. In the box plots, red circles indicate DL1; green circles indicate DL2; blue circles indicate DL3. Boxes cover central 50% of observations, and the central bars show median; whiskers extend to at most 1.5 times box length with more extreme observations shown individually (colored circles). Colored lines represent means for each DL, and black dotted lines show the fitted means (referred as “Model” in the upper right box) on a square-root scale from a piecewise linear GEE model, with a change in slope at day 42 and no DL distinction. Thinner lines indicate the responses profiles for the 3 CMV seronegatives enrolled in the study. UPN 14 (DL2) and 18 (DL3) remained CMV seronegative until day 180, but tested CMV seropositive at day 360. UPN 13 (DL2) received smallpox vaccination. Arrows indicate Triplex vaccine injection. (B) Representative dot plots and gating hierarchy. In the top row, the primary gate set on lymphocytes by use of forward and side scatter is shown. Histogram plots indicate (from left to right) the CD8 (fluorescein isothiocyanate [FITC] conjugated) gating, and the subsequent gating of CD8⁺ CD137⁺ (allophycocianin [APC] conjugated) T cells from CMV-seronegative UPN 14, stimulated with the pp65 library on day 180 post-Triplex vaccination (as indicated by the arrow). In the upper right gate of each dot plot, the percentage of CD8⁺ CD137⁺ T cells in pp65 stimulated (upper dot plots) and unstimulated (lower dot plots) PBMC samples are shown collected at the post-Triplex vaccination days indicated.