Propagation and Assay of BK Virus

BK virus (BKV), one of two human polyomaviruses, was first isolated in cell culture from the urine of an immunocompromised renal transplant patient in England in 1971 (1 ). Seroprevalence studies have shown that BK infection is widespread in children throughout the world, and the virus thereafter persists latently in the kidney for life. Immunosuppression can lead to reactivation of the virus and prolonged viruria (2 ). Although in immunocompetent individuals BK infection is generally asymptomatic, lowering of immunity can occasionally result in life-threatening renal disease (3 ,4 ). An association between active BKV infection and ureteric stenosis in renal transplant recipients, and hemorrhagic cystitis in bone marrow transplant patients has long been established (2 ), and recent evidence suggests that BK may contribute to further complications arising in immunocompromised groups, e.g., interstitial pneumonia (5 ) and atypical retinitis (6 ).