Polyomavirus BK and JC infections in well matched Finnish kidney transplant recipients

Summary Since 2003, only one case of polyomavirus-associated nephropathy (PVAN) has occurred in our clinic despite screening protocols. In contrast to BK virus, the role of JC virus in PVAN is unclear. We studied the incidence and impact of polyomavirus BK and JC viruria and PVAN in well-matched Finnish kidney transplant recipients. All Helsinki University Hospital kidney transplant recipients between 2004 and 2006 were prospectively followed (n = 163). Patients with a 12-month protocol-biopsy taken and polyomavirus urinary secretion screened by PCR were studied (n = 68). Cyclosporine-based triple-drug immunosuppression was usually used. BK or JC viruria was detected in 18 (27%) and 14 (21%) patients after transplantation respectively. Persistent BK or JC viruria was found in 5 (7%) and 9 (13%) patients. No cases of PVAN were diagnosed from protocol biopsies or from biopsies taken for clinical indications. A positive BK or JC viruria or persistent viruria was not associated with reduced renal function at follow-up, histopathologic changes in 12-month protocol biopsies, or acute rejections. The incidence of BK and JC viruria was similar to what has been previously reported, but no cases of polyomavirus-associated nephropathy were seen in our well-matched kidney transplant population.