An emerging viral pathogen causing pyelonephritis in kidney allograft recipients is

*Causes of viral lesions in renal transplantation : Polyomavirus, cytomegalovirus, adenovirus, Ebstein Barr virus and by far the most common infection involving kidney transplants are polyoma virusPolyoma virus nephropathy:*Polyoma virus are double stranded, non encapsulated DNA virus*Types of polyoma virus are BK virus and JC virus and BK virus is the common cause of polyoma virus nephropathy in renal transplants*BK virus affects and thereby causes intra nuclear inclusions in collecting ducts of medulla, parietal epithelium of glomerulus, transitional cell in renal pelvis, ureters and urinary bladder.*Note that not all those who are infected by Bk virus develops disease. *Infection of polyoma virus/BK virus is seen in -almost all humans*Disease caused by polyoma virus/BK virus is seen only in - renal transplant recipients.(Ref: Hepinstall pathology of the kidney 6/e p1441)