Validation of the QIAsymphony RGQ system for DNA quantitation of different BK virus genotypes in whole blood samples

Human polyomavirus BK (BIN) is increasingly recognized as an opportunistic pathogen in transplant recipients. The aim of this work was to evaluate the artus((R)) BK Virus QS-RGQ assay on the QlAsymphony RGQ system in whole blood (WB) samples (tests performed in an off-label capacity) according to different BKV genotypes by comparison with a laboratory-developed assay. BKV loads were measured in 111 WB samples and BKV genotype was determined by sequencing the full-length VP1 gene. The anus assay exhibited a limit of detection of 77 copies/mL, a linearity range from 3.0 to 6.0 log(10) copies/mL, intra-assay and inter-assay coefficients of variation ranging from 0.65% to 5.18%. Regarding BKV quantitation, artus((R)) and laboratory-developed assays were highly correlated (Spearman correlation coefficient Rho=0.79; P<0.0001) with an excellent overall agreement (96.4%) and no significant quantitative difference according to Bland-Altman analysis (mean difference: -0.34 log(10) copies/mL). The results did not show any influence of BIN genotype on BIN quantitation by the artus((R)) assay, except a potential under-quantitation of BICV subtype Ia which deserves further confirmation. In conclusion, the QIAsymphony RGQ system appears to be appropriate for the quantitation of BKV load in WB samples. (C) 2013 Elsevier B.V. All rights reserved.