BK Polyomavirus Infection in Kidney Transplantation: A Comprehensive Review of Current Challenges and Future Directions.

BK polyomavirus (BKPyV) infection of the kidney graft remains a major clinical issue in the field of organ transplantation. Risk factors for BKPyV-associated nephropathy (BKPyVAN) and molecular tools for determining viral DNA loads are now better defined. BKPyV DNAemia in plasma, in particular, plays a central role in diagnosing active infection and managing treatment decisions. However, significant gaps remain in the development of reliable biomarkers that can anticipate BKPyV viremia and predict disease outcomes. Biomarkers under active investigation include urine-based viral load assays, viral antigen detection, and immune responses against BKPyV, which may offer more precise methods for monitoring disease progression. In addition, treatment of BKPyVAN is currently based on immunosuppression minimization, while the role of adjunctive therapies remains an area of active research, highlighting the need for more personalized treatment regimens. Ongoing clinical trials are also exploring the efficacy of T-cell-based immunotherapies. The clinical management of BKPyV infection, based on proactive virological monitoring, immune response assessment, integrated histopathology, and timely immunosuppression reduction, is likely to reduce the burden of disease and improve outcomes in kidney transplantation.