Comparison of 2 highly automated nucleic acid extraction systems for quantitation of human cytomegalovirus in whole blood

The aim of the study was to evaluate analytical performances of the COBAS Ampliprep™ and to compare extraction from whole blood on the COBAS Ampliprep™ and on the MagNA Pure™ instruments (Roche Diagnostics, Mannheim, Germany) for quantifying human cytomegalovirus (HCMV) DNA with real-time polymerase chain reaction (PCR). The limit of detection using the COBAS Ampliprep™ was 10 copies/run (150 copies/mL, i.e., 2.20 log10 copies/mL). Quantitation of HCMV-DNA was linear from 3.0 to 6.0 log10 copies/mL. The intra-assay variations ranged from 11.1 % to 0.4 % and interassay variation was 11.3 %. A total of 107 samples were tested using both extraction systems. Only 3 samples gave discrepant results. Correlation between HCMV virus loads was good (r = 0.73) (P < 0.001). Mean virus load was lower (−0.49 log10 copies/mL) with COBAS Ampliprep™ than with MagNA Pure™ extraction system. Both MagNA Pure™ and COBAS Ampliprep™ provide reliable and high-throughput platforms for real-time PCR HCMV quantitation of DNA extracted from whole blood.