CPT11 prevents virus replication in JCI cells persistently infected with JC polyomavirus

JC polyomavirus (JCPyV) is the causative agent of the demyelinating disease of the central nervous system known as progressive multifocal leukoencephalopathy (PML), which occurs in immunocompromised patients. Moreover, patients treated with natalizumab for multiple sclerosis or Crohn disease can develop PML, which is then termed natalizumab‐related PML. Because few drugs are currently available for treating PML, many antiviral agents are being investigated. It has been demonstrated that the topoisomerase I inhibitors topotecan and β‐lapachone have inhibitory effects on JCPyV replication in IMR‐32 cells. However, both of these drugs have marginal inhibitory effects on virus propagation in JC1 cells according to RT‐PCR analysis. In the present study, the inhibitory effect of another topoisomerase I inhibitor, 7‐ethy‐10‐4‐(1‐piperidino)‐1‐piperidino] carbonyloxy camptothecin (CPT11), was assessed by investigating viral replication, propagation, and viral protein 1 (VP1) production in cultured cells. JCPyV replication was assayed using real‐time PCR combined with Dpn I treatment in IMR‐32 cells transfected with JCPyV DNA. It was found that JCPyV replicates less in IMR‐32 cells treated with CPT11 than in untreated cells. Moreover, CPT11 treatment of JCI cells persistently infected with JCPyV led to a dose‐dependent reduction in JCPyV DNA and VP1 production. Additionally, the inhibitory effect of CPT11 was found to be stronger than those of topotecan and β‐lapachone. These findings suggest that CPT11 may be a potential anti‐JCPyV agent that could be used to treat PML.