Monthly screening for polyoma virus eliminates BK nephropathy and preserves renal function

Background: Polyoma BK virus nephropathy is a serious complication after renal transplantation and is associated with a high rate of allograft failure. Progressive infection with BK virus in immunocompromised renal transplant recipients occurs in detectable stages: Viruria, viremia, then nephropathy. Methods: In January, 2006, we initiated a plasma screening policy for all new transplant recipients, with monthly blood testing for BK virus by polymerase chain reaction (PCR). Between January 1, 2006, and February 28, 2007, 66 renal transplants were performed at our center. The 11 patients with a positive plasma BK PCR test underwent prompt reduction in baseline immunotherapy consisting of a 50% daily dose reduction (n = 6) or complete discontinuation of therapy with mycophenolate mofetil (n = 5). Results: After reduction or discontinuation of mycophenolate mofetil, 10 patients became negative for BK virus in the plasma within 6 months. Progression to BK nephropathy has not occurred, and renal transplant dysfunction secondary to acute cellular rejection developed in only 1 patient (9%). One year post-transplant, the mean serum creatinine values for these 11 patients remained stable at 1.5 mg/dL. Conclusion: Monthly plasma screening for BK virus by PCR together with immunosuppressive regimen reduction prevents BK nephropathy. In addition, this intensive screening protocol is associated with a low rate of acute rejection and excellent preservation of renal function.