title: Cytomegalovirus quantification in plasma by an automated real-time PCR assay.
abstract: 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.
  
  
  OBJECTIVE
  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 (<300 copies/ml); 18 samples were positive by CMV real-time PCR only, and 2 samples by ultrasensitive Cobas CMV only. Values obtained by CMV real-time PCR were on average 0.4 log higher than those of ultrasensitive Cobas CMV. Successive samples of transplanted patients with evidence of CMV infection/reactivation revealed that CMV real-time PCR assay was positive earlier and for a longer period of time after treatment initiation.
  
  
  CONCLUSIONS
  Although both assays had similar analytical performances, the CMV real-time PCR assay has the advantages of automated extraction and higher dynamic range, and shows a trend for an improved sensitivity that might impact on clinical decisions.
authors.affiliation: Laboratory of Virology, University of Geneva Hospitals, 24 Rue Micheli-du-Crest, 1211 Geneva 14, Switzerland. sabine.yerly@hcuge.ch <sabine.yerly@hcuge.ch>
authors.forename: Sabine
authors.initials: S
authors.lastname: Yerly
authors.forename: Luc
authors.initials: L
authors.lastname: Perrin
authors.forename: Christian
authors.initials: C
authors.lastname: Van Delden
authors.forename: Sven
authors.initials: S
authors.lastname: Schaffer
authors.forename: Sven
authors.initials: S
authors.lastname: Thamm
authors.forename: Werner
authors.initials: W
authors.lastname: Wunderli
authors.forename: Laurent
authors.initials: L
authors.lastname: Kaiser
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D003587:Cytomegalovirus / Q000235:genetics*; D004279:DNA, Viral / Q000097:blood*; D005260:Female; D006801:Humans; D010949:Plasma / Q000821:virology; D016133:Polymerase Chain Reaction / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019562:Viral Load / Q000379:methods*
chemical_list: D004279:DNA, Viral