Comparison of various blood compartments and reporting units for the detection and quantification of Epstein-Barr virus in peripheral blood

Abstract

Epstein-Barr virus (EBV) infection is associated with a broad spectrum of disease. While quantification of EBV nucleic acid in the peripheral blood has been demonstrated to be useful for diagnosis and patient care, the optimal sample type and reporting format for such testing remain uncertain. Using quantitative real-time PCR (QRT-PCR), we evaluated EBV in whole blood (WB), peripheral blood mononuclear cells (PBMC), and plasma in 249 samples from 122 patients. In WB and PBMC, results were reported both in viral copies/ml and in copies/microg of total DNA. Trendings of quantitative values over time among the different sample types were compared. The sensitivities of QRT-PCR using WB and that using PBMC did not differ significantly (P = 0.33), and both were more sensitive than plasma alone (P < 0.0001). EBV viral load results from WB and PBMC paired sample types also showed a significant correlation (P < 0.05), as did results reported in copies/ml and copies/microg DNA for both WB and PBMC (R2 > 0.93). EBV viral loads detected using WB and PBMC trended very closely for the few patients who had multiple positive samples available for analysis. WB and PBMC show comparable sensitivities and a close quantitative correlation when assayed for EBV by QRT-PCR. The close correlation between copies/ml and copies/microg DNA also suggests that normalization to cell number or genomic DNA in cellular specimens may not be necessary.

FIG. 1.

Comparison between EBV viral loads in WB and PBMC expressed in log₁₀.

FIG. 2.

Comparison of the two reporting formats in WB and PBMC, with all viral loads expressed in log₁₀. (a) Comparison between EBV viral loads of copies/μg and copies/ml for WB. (b) Comparison between EBV viral loads of copies/μg and copies/ml for PBMC.

FIG. 3.

Comparative trends of EBV viral loads in different sample types from two individual patients (a and b). Solid line, WB; dotted line, PBMC.

FIG. 4.

Comparative trends of EBV viral loads in WB from a patient by use of two different reporting units. Solid line, copies/ml; dotted line, copies/μg DNA.

FIG. 5.

Comparative trends of EBV viral loads in PBMC from a patient by use of two different reporting units. Solid line, copies/ml; dotted line, copies/μg DNA.