Expression of IL-7Rα on virus-specific cells is low during primary infection. (A) (top row) CMV-specific CD8⁺ T cells during primary CMV infection. (bottom row) Phenotypes of total CD8⁺ T cells (red) and CMV-specific T cells (black). (B) Same as panel A but showing primary EBV infection measured by CD8⁺ T cells specific for the lytic epitope RAK (first 2 rows) and the latent epitope FLR (last 2 rows). (C) Changes in phenotype of CD8⁺ T cells and CMV-specific CD8⁺ T cells (measured with CMV A2 tetramer) during CMV reactivation. wk indicates the number of weeks after transplantation; + and - indicate the relative heights of the viral load as measured by PCR. Percentages are the percentages of virus-specific cells within CD8⁺ T cells. Dot plots show the phenotypes of CD8⁺ T cells (red) and of virus-specific CD8⁺ T cells (black). Numbers indicate percentages within virus-specific cells in the corresponding quadrants. For clarity, only 10% of the dots are shown from dot plots showing RAK-specific cells during primary EBV infection; all other plots show 100% of measured events. Representative results of flow cytometric analysis are shown for 1 of 6 patients with primary CMV infection and 1 of 2 patients with CMV reactivation.