This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infectious Disease, Subject name: Pathology
[{'content': 'BK virus infection - True statement is: \nSelect and explain. \nA. Causes nephropathy in transplant patients, B. Causes progressive multifocal leukoencephalopathy, C. 20 - 25% transplant cases associated with BK virus nephropathy, D. Single stranded DNA virus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 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).', 'role': 'assistant'}]