title: Multicenter comparison of different real-time PCR assays for quantitative detection of Epstein-Barr virus.
abstract: Quantification of Epstein-Barr virus (EBV) in peripheral blood is important for the diagnosis and management of serious EBV diseases, including posttransplant lymphoproliferative disorder. A variety of PCR-based methods are currently in use; however, there is little information on their comparability. This study assessed the relative performance of different quantitative assays. A multicenter comparative study was performed at eight sites using three panels consisting of serial dilutions of quantified EBV DNA and extracts from a total of 19 whole-blood specimens. Samples were distributed and tested blindly. Instrumentation, probe chemistries, amplification targets, and other test-related aspects varied considerably between laboratories. Each laboratory's calibration curve indicated strong evidence of a consistent log-linear relationship between viral load and cycle threshold, suggesting that intralaboratory tracking of a given patient would yield similar relative quantitative trends among the participating test sites. There was strong concordance among laboratories with respect to qualitative test results; however, marked quantitative discordance was seen. For most samples, the across-laboratory interquartile range of the reported viral load (in copies/microl) was roughly 0.6 log-units, and for one sample the overall range was approximately 4.2 log-units. While intralaboratory tracking of patients may yield similar results, these data indicate a need for caution when attempting to compare clinical results obtained at different institutions and suggest the potential value to be gained by more standardized testing methodology.
authors.affiliation: Department of Pathology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors.forename: R T
authors.initials: RT
authors.lastname: Hayden
authors.forename: K M
authors.initials: KM
authors.lastname: Hokanson
authors.forename: S B
authors.initials: SB
authors.lastname: Pounds
authors.forename: M J
authors.initials: MJ
authors.lastname: Bankowski
authors.forename: S W
authors.initials: SW
authors.lastname: Belzer
authors.forename: J
authors.initials: J
authors.lastname: Carr
authors.forename: D
authors.initials: D
authors.lastname: Diorio
authors.forename: M S
authors.initials: MS
authors.lastname: Forman
authors.forename: Y
authors.initials: Y
authors.lastname: Joshi
authors.forename: D
authors.initials: D
authors.lastname: Hillyard
authors.forename: R L
authors.initials: RL
authors.lastname: Hodinka
authors.forename: M N
authors.initials: MN
authors.lastname: Nikiforova
authors.forename: C A
authors.initials: CA
authors.lastname: Romain
authors.forename: J
authors.initials: J
authors.lastname: Stevenson
authors.forename: A
authors.initials: A
authors.lastname: Valsamakis
authors.forename: H H
authors.initials: HH
authors.lastname: Balfour
mesh_terms: D002138:Calibration / Q000592:standards; D004279:DNA, Viral / Q000097:blood*; D020031:Epstein-Barr Virus Infections / Q000821:virology*; D004854:Herpesvirus 4, Human / Q000302:isolation & purification*; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*; D015203:Reproducibility of Results; D019562:Viral Load / Q000379:methods* / Q000592:standards
chemical_list: D004279:DNA, Viral