JCV virus establishes latency in the kidney and virus is shed sporadically through life and more frequently during pregnancy or immunosuppression. JC virus causes progressive multifocal leukoencephalopathy (PML), which is a subacute demyelinating disease of the CNS and is seen mainly in advanced disseminated malignant conditions, immunodeficiency syndromes, and in immunosrppressed patients following organ transplantation. The disease PML represents a reactivation of longstanding persistent infection of the kidney and perhaps also of the brain. JC virus has also been associated with hemorrhagic cystitis, ureteral stenosis and allograft dysfunction. Test sent to Viracor Eurofins.