Immunosuppressive agents as risk factors for BK virus nephropathy: an overview and update

Abstract

BK virus has emerged as an important cause of graft dysfunction and failure in renal transplant recipients. Risk factors for BK virus nephropathy (BKN) are not well established, but evidence suggests that it is the result of a complex interplay between multiple donor- and recipient-related factors. The purpose of this article is to review the current understanding on the effect of various immunosuppressive agents on BK viral replication and the results of different reported immunosuppression reduction protocols. The intensity of overall immunosuppression has been accepted as a major risk factor for the development of BKN. We review the data regarding the contribution of different anti-rejection agents to the risk of BK virus-induced graft injury. Although reduction in immunosuppression on detection of BK viral replication appears to be the most successful means in preserving allograft function, data are emerging that support the stronger association of the disease with tacrolimus, in contrast to mycophenolate compounds. Therefore, initial dose reduction for tacrolimus may be more beneficial than this anti-metabolite preemptively or after diagnosis of BKN.