<prompt> BK virus infection - True statement is:Causes nephropathy in transplant patientsCauses progressive multifocal leukoencephalopathy20 - 25 transplant cases associated with BK virus nephropathySingle stranded DNA virus  <response>: Ans: a Causes nephropathy in transplant patientsRef: Harrison, 19th editionBK VirusBK virus is a non-enveloped double-strand DNA virus which belongs to family polyoma viridae.Primary BKV infection occurs by the upper respiratory route until age 10 without any obvious symptoms.80 of the population is infected by BKV, and approximately 50 of healthy native kidneys contain latent BKV.After renal transplantation, 35-60 of patients have BKV viruria, 5-30 of patients have BKV viremia.The prevalence of BKV nephropathy is about 10 of renal transplant patients.Progressive multifocal leukoencephalopathy is caused by JC virus belongs to polyoma viridae. 