Sample Processing Effect on BK Virus Detection by Real-Time PCR in Urine Samples

Background: Measurement of BK viral DNA in urine by quantitative real-time PCR is a useful tool in monitoring BK viruria and nephropathy. We conducted this study to evaluate the differences in BK virus detection by different sample processing. Methods: A total of 140 samples from 60 patients were processed by different methods including DNA extraction by spin column from whole urine, urine sediment, and urine supernatant. Boiled urine sediment lysate and untreated urine were also used in this study. Results: The positive rate of BK virus was 34% for whole urine while other methods ranged from 21% - 27%. The quantification data showed that the maximum difference between whole urine and other methods varies from 2.36 - 2.47 log copies/mL in detection of BK virus load, while other methods showed minor differences. Conclusions: Our results highlight that centrifugation may cause BKV DNA to be lost in urine samples and whole urine is preferred for BK virus monitoring.