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

Abstract

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 log(10) copies/mL). Quantitation of HCMV-DNA was linear from 3.0 to 6.0 log(10) 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 log(10) 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.