Human polyomavirus BK (BKV) is increasingly recognized as an opportunistic pathogen in transplant recipients. The aim of this work was to evaluate the artus(®) BK Virus QS-RGQ assay on the QIAsymphony 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 artus(®) assay exhibited a limit of detection of 77copies/mL, a linearity range from 3.0 to 6.0log10copies/mL, intra-assay and inter-assay coefficients of variation ranging from 0.65% to 5.18%. Regarding BKV quantitation, artus(®) 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: -0.34log10copies/mL). The results did not show any influence of BKV genotype on BKV quantitation by the artus(®) assay, except a potential underquantitation of BKV 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.
Keywords: Automation; BK virus; Genotype; Viral load; Whole blood.
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