Cellular EBV loads in allo-HSCT patients. Cell-associated EBV loads were determined by Q-PCR screening of PBMC DNA from no/low EBV patients at around 3, 6, and 12 months posttransplant, and from high EBV patients at the time of peak EBV DNAemia. Viral loads from healthy control donors are included as a reference. The solid horizontal lines represent the medians of the positive values for each group. For the no/low EBV group, the median EBV loads from samples available at 3, 6, and 12 months posttransplant were 600, 1800, and 2700 EBV copies per 106 PBMCs, respectively. The median value for the high EBV group, collected at a median of 109 days posttransplant (IQR, 92-141 days), was 5.9 × 105 EBV copies per 106 PBMCs. Of the healthy controls with detectable EBV, the median viral load was 73 EBV copies per 106 PBMCs. For purposes of statistical analysis, comparison with the no/low EBV group was made with samples combined from the 3- and 6-month time points collected at a median of 112 days posttransplant (IQR, 84-169 days). EBV loads in the high EBV group were significantly higher than those of the no/low group (P < .0001). The dotted horizontal lines represent the limit of detection of the assay (10 EBV copies per 106 PBMCs) and samples with undetectable virus DNA were assigned a value of 1.
