Noninvasive diagnosis of BK virus nephritis by measurement of messenger RNA for BK virus VP1 in urine.

Background: Polyoma virus type BK (BKV) nephritis has emerged as an important cause of renal allograft dysfunction and graft failure. Its diagnosis is contingent on the invasive procedure of allograft biopsy. A noninvasive diagnostic test for BKV nephritis could improve clinical outcome.