title: CMV antigenemia and quantitative viral load assessments in hematopoietic stem cell transplant recipients.
abstract: BACKGROUND
  Sensitive and reliable diagnostic tests are essential for the prevention of cytomegalovirus (CMV) disease after hematopoietic stem cell transplantation (HSCT). pp65 antigenemia and polymerase chain reaction (PCR) assays are commonly used to monitor CMV in HSCT recipients. However, there is considerable intra- and inter-laboratory variability in the results, which impact comparability and clinical practice.
  
  
  OBJECTIVE
  Using 380 samples from 135 HSCT recipients, we compared the new FDA approved quantitative PCR assay, COBAS(®) AmpliPrep/COBAS(®) TaqMan(®) CMV test (CAP/CTM CMV test) developed and standardized using the 1st WHO International Standard for CMV with pp65 antigenemia and COBAS(®) AMPLICOR MONITOR CMV tests.
  
  
  RESULTS
  The median time between transplantation and testing samples was 57 days (range, 0-207 days). The median CMV load (log(10)) was 3.17 IU/mL (3.21 copies/mL). Among samples with detectable CMV load, 52% were negative by pp65 antigenemia. CMV loads were higher in pp65 antigenemia-positive than in negative samples. One pp65-antigenemia-positive cell per 100,000 leukocytes corresponded to a median CMV load of 1200 IU/mL. CMV loads determined by the CAP/CTM CMV test were slightly lower than the ones by the AMPLICOR MONITOR CMV test (-0.15 [95% CI, -0.18 to -0.13] copies/mL), but slope differences indicated only limited co-linearity.
  
  
  CONCLUSIONS
  The CAP/CTM CMV test is more sensitive than pp65 antigenemia and the AMPLICOR MONITOR CMV test in HSCT recipients. The lower limit of quantification and co-linearity with the international WHO standard renders the CAP/CTM CMV test suitable for future clinical trials defining viral load thresholds of CMV therapy.
authors.affiliation: Hospital Universitario de la Princesa, Madrid, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Cardeñoso
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Pinsky
authors.forename: Irmeli
authors.initials: I
authors.lastname: Lautenschlager
authors.forename: Shagufta
authors.initials: S
authors.lastname: Aslam
authors.forename: Bryan
authors.initials: B
authors.lastname: Cobb
authors.forename: Regis A
authors.initials: RA
authors.lastname: Vilchez
authors.forename: Hans H
authors.initials: HH
authors.lastname: Hirsch
mesh_terms: D000328:Adult; D000956:Antigens, Viral / Q000097:blood*; D003587:Cytomegalovirus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D003586:Cytomegalovirus Infections / Q000175:diagnosis* / Q000821:virology; D004279:DNA, Viral / Q000097:blood*; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods; D012680:Sensitivity and Specificity; D014180:Transplantation; D019562:Viral Load / Q000379:methods*; D055815:Young Adult
chemical_list: D000956:Antigens, Viral; D004279:DNA, Viral