Introduction. BK polyomavirus (BKPyV) quantitative testing is an important screening tool post-transplantation, although interpretation can be challenging due to lack of standardization, assay heterogeneity and variability of BKPyV DNA over time (in urine). Methods. Remnant clinical EDTA plasma and urine samples were tested by the cobas BKV test and a validated laboratory-developed test (LDT). Accuracy [positive and negative percent agreement (PPA and NPA), Pearson’s correlation, Bland–Altman analysis] and reproducibility were evaluated. To assess BKPyV DNA stability in urine, prospective urine samples were maintained at two different storage temperatures and tested in triplicate over 7 days. Results. Overall PPA was 95.6 % (43/45) and NPA was 94.4 % (170/180). For plasma, Pearson’s correlation (0.950) and Bland–Altman analysis (0.113±0.22 log10 IU ml–1) showed high agreement. For neat urine, Pearson’s correlation (0.842) and Bland–Altman analysis (0.326±0.80 log10 IU ml–1) showed somewhat higher variability. Reproducibility was high for the cobas BKV versus the LDT. BKPyV DNA levels in neat urine remained relatively stable over 7 days at both storage temperatures, although outlier results were intermittently detected. Conclusion. The cobas BKV test showed high agreement and reproducibility compared to the reference LDT. BKPyV viral load testing in urine has known limitations, but neat urine can be processed by the cobas BKV.

中文翻译：

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尿液中 BK 多瘤病毒 DNA 随时间的稳定性以及自动化 BKV 定量核酸测试的分析评估

介绍。BK 多瘤病毒 (BKPyV) 定量检测是移植后的重要筛查工具，但由于缺乏标准化、检测异质性以及 BKPyV DNA 随时间变化（尿液中）的变异性，解释可能具有挑战性。方法。剩余的临床 EDTA 血浆和尿液样本通过 cobas BKV 测试和经过验证的实验室开发的测试 (LDT) 进行测试。评估了准确性[正负百分比一致性（PPA 和 NPA）、Pearson 相关性、Bland-Altman 分析]和再现性。为了评估尿液中 BKPyV DNA 的稳定性，将前瞻性尿液样本保存在两种不同的储存温度下，并在 7 天内一式三份进行测试。结果。总体 PPA 为 95.6 % (43/45)，NPA 为 94.4 % (170/180)。对于血浆，Pearson 相关性 (0.950) 和 Bland-Altman 分析 (0.113±0.22 log 10 IU ml –1 ) 显示出高度一致性。对于纯尿，Pearson 相关性 (0.842) 和 Bland-Altman 分析 (0.326±0.80 log 10 IU ml –1 ) 显示出较高的变异性。与 LDT 相比，cobas BKV 的重现性较高。尽管间歇性检测到异常结果，但在两种储存温度下，纯尿液中的 BKPyV DNA 水平在 7 天内保持相对稳定。结论。与参考 LDT 相比，cobas BKV 测试显示出较高的一致性和重现性。尿液中的 BKPyV 病毒载量检测具有已知的局限性，但 cobas BKV 可以处理纯尿液。