The detection of BKPyV genotypes II and IV after renal transplantation as a simple tool for risk assessment for PyVAN and transplant outcome already at early stages of BKPyV reactivation

Abstract Background After reactivation the BK-polyomavirus (BKPyV) associated nephropathy (PyVAN) is observed in 1–10% of renal transplant recipients, of which up to 80% undergo graft failure. BKPyV reactivation after renal transplantation was associated with donor-derived serotypes against which the recipient has no immunological protection. However, PyVAN risk assessment seroactivity testing is a time-consuming and cost intensive process. Objectives Since BKPyV serotypes can be attributed to distinct genotypes I to IV, in the present study we retrospectively analyzed whether a simple PCR-based BKPyV genotyping assay might be a fast and inexpensive method to assess the risk for PyVAN and transplant outcome already at early stages of BKPyV reactivation. Study design 56 patients who were renal transplanted and tested positive for BKPyV viremia were included into the study. The BKPyV-VP1-coding sequences were PCR-amplified, sequenced, and subjected to genotyping. For group specific analysis patients were grouped in genotype I (n = 46) and a second group including genotype II and IV (n = 10) and associated with their clinical outcomes. Results The most abundant genotype I was detected in 46 of 56 (82%) patients, however, in the genotype II and IV group PyVAN was twice as frequent as compared to the genotype I group 24 months after transplantation (8 of 10 (80%) vs. 17 of 46 (37%); p = 0.001). Accordingly, graft failure was significantly more frequent in the genotype II and IV group (3 of 10 (30%) vs. 2 of 46 (4%); p = 0.007). Conclusion PCR-based BKPyV genotyping might represent a fast and inexpensive method to assess the risk for PyVAN and transplant outcome already at early stages of BKPyV reactivation even if matched samples of the donor are not available.