Background: Cidofovir and Leflunomide are used empirically in the treatment of BK virus nephropathy. The aim of this study is to quantify the antiviral activity of these drugs.
Methods: BK virus was grown in a cell-culture system. The rate of viral replication in the presence or absence of the drug being tested was assessed using a quantitative polymerase chain reaction assay.
Results: The inhibitory concentration, effective concentration, and selectivity index for Leflunomide are 39.7+/-6.9, 11.3+/-2.8, and 3.8+/-0.8 microg/mL, respectively. For Cidofovir, these indices were, respectively, 63.9+/-17.2, 36.3+/-11.7, and 2.3+/-0.8 microg/mL.
Conclusions: The in vitro activity of Cidofovir and Leflunomide is modest, and the selectivity index is low. There is a need to develop more effective and less toxic anti-BK virus drugs for clinical use.