Review The human polyomaviruses

The Polyomavirus family includes two mem- bers, BK virus (BKV) and JC virus (JCV), that natu- rally infect humans. These viruses are widely distributed among the population worldwide. Primary infection oc curs in early childhood and remains for life clinically unapparent in immunocompetent individuals. In the con- text of severe immunosuppression and other predisposing factors BKV and JCV may reactivate and cause serious illnesses known as Polyomavirus-induced nephropathy and progressive multifocal leukoencephalopathy, respec- tively. Here we briefly examine the biological and physical characteristics and the lifecycle, namely receptor(s) inter- action, mode of entry, intracellular trafficking, viral tran- scription and replication, and progeny assembly of these two human Polyomaviruses. We also provide an overview of the clinical manifestation of Polyomavirus-induced disorders in affected individuals and discuss the potential involvement of BKV and JCV in human cancer.