Contribution of ORF-specific T-cell response to the total CMV-specific T-cell response in the donor and recipient after HSCT. (A) Targeting patterns of CMV-specific memory CD4⁺ (left panels) and CD8⁺ (right panels) T-cell responses in representative donor-recipient pairs. The summation of responses measured by 5 functional outputs is shown for each ORF (CD4⁺ and CD8⁺) tested and for whole CMV lysate (CD4⁺ only); donor (green), recipient before HSCT (red), and recipient after HSCT (yellow). Response breadth (ie, the number of targeted ORFs) and dominance patterns (ie, the ORF-specific responses representing the majority of the total response) showed substantial variability. In some cases, pp65 and IE-1 were preferentially targeted (eg, ID 1 and ID 3 CD8⁺ T-cell responses); in other cases, the predominant responses were directed against different ORFs (eg, ID 7 CD8⁺ T-cell responses). In some cases, the CD4⁺ T-cell responses to whole CMV lysate were less than the summation of the ORFs, which may reflect the negative effect of freeze/thawing in lysate processing for peptide recognition. *Patients who received a DLI. (B) Contribution of each ORF-specific response to the total CD4⁺ (left panel) and CD8⁺ (right panel) CMV-specific T-cell response plotted for donors against recipients after HSCT. In each case, the ORF-specific response was normalized such that the contribution of each targeted ORF (in percentage) to the total CMV-specific T-cell response was calculated. Only the normalized data are shown.