Cytomegalovirus quantification in plasma by an automated real-time PCR assay

BACKGROUND: Sensitive quantitation of cytomegalovirus (CMV) DNA in blood is helpful for the diagnosis of CMV infection or reactivation and the monitoring of transplanted patients. OBJECTIVES: We compared a new PCR assay coupled with an automated extraction system (CMV real-time PCR, Abbott Molecular, Des Plaines, IL, USA) to a previously validated method (ultrasensitive Cobas Amplicor CMV DNA Monitor, Roche Molecular, Indianapolis, IN, USA). RESULTS: Using limiting dilutions of CMV DNA positive plasma, the two assays had a similar detection threshold ranging between 20 and 45 copies/ml. Coefficients of variation of CMV real-time PCR assay varied from 1 to 12% for CMV DNA levels between 10,000 and 20 copies/ml. Viral loads assessed by the two methods on 179 clinical samples showed an overall concordance of 89% and an excellent correlation (R=0.94). Discrepancies were only observed for samples with low CMV DNA levels (