Comparison of two highly automated DNA extraction systems for quantifying Epstein–Barr virus in whole blood

BackgroundOptimal automated molecular methods are needed to monitor Epstein–Barr virus (EBV) infections in transplant recipients.ObjectivesTo compare the extraction of EBV DNA from whole blood using the COBAS Ampliprep™ and the MagNA Pure™ instruments (Roche) for quantifying EBV DNA by real-time PCR.Study designEBV DNA content was determined on clinical samples extracted by both systems.ResultsThe detection limit was 2.16 log10 copies/mL using the COBAS Ampliprep™ extraction system. Specificity was 100% and we saw no cross-contamination. Extraction was linear from 2.60 to 5.60 log10 copies/mL. The intra-assay variation was 1.91% for 3.60, 2% for 4.60 and 4.51% for 5.60 log10 copies/mL; inter-assay variation was 4.88%.Sixty-six samples were tested: 26 were positive and 28 were negative by both methods. One sample was MagNA Pure™ positive/COBAS Ampliprep™ negative (virus load 3.15 log10 copies/mL) and 10 samples were MagNA Pure™ negative/COBAS Ampliprep™ positive (virus loads from 1.59 to 3.51 log10 copies/mL) (P < 0.0001). Both methods gave similar quantitative results (average difference 0.07 log10 copies/mL) which were well correlated (r = 0.73, P < 0.001).ConclusionsThe COBAS Ampliprep™ extraction system is comparable to the MagNA Pure™ and offers a high reliability for extracting EBV DNA from whole blood.