<prompt> Which of the following clinical specimen for detection of BK polyomavirus by electron microscopy?Brain tissuesUrineBloodNone of the above  <response>: Ans. is b i.e., Urine Ref: Dr D.R. Arora, 3rde, p. 552 BK virus was isolated from urine of a renal transplant recipient, causes subclinical infection of children before the age of 10; virus persists for throughout life in kidneys. Reactivation may occur in last trimester of pregnancy and following immunosuppression for organ transplantation. 