BK virus in liver transplant recipients: a prospective study.

Background. BK virus (BKV) is a polyomavirus that is associated with nephropathy and graft loss among kidney transplant recipients. The role of BK virus in nonrenal solid organ transplant recipients has not been clearly established; only anecdotal case reports have been published. Methods. From August 2005 to September 2007, all orthotopic liver transplant (OLT) recipients who gave their consent were enrolled in this prospective longitudinal study. BK viral load was measured using real-time quantitative polymerase chain reaction assays of urine and plasma, using samples collected at week 1 and months 1, 3, 6, 9, 12, 15, 18, 21, and 24 posttransplantation. We also collected demographic and clinical data, including serum creatinine and immunosuppressive therapy. Results. The mean age of the 62 patients was 51.4 years including 14 (22.5%) women. Hepatitis C infection was present in 24 patients (38.7%). BK viruria was detected in 14.5% of 290 samples, corresponding to 13 patients (21%). BK viremia was detected in 5.1% of 317 samples, corresponding to 11 patients (18%). Almost all cases of BK viremia (91%) occurred in the first 3 months after OLT. BK viremia was more common among patients experiencing a rejection episode (10.6 vs 40%, P .01). We did not observe a relationship between single episodes of BKV replication and renal function: median plasma creatinine 1.1 mg/dL in patients without versus 1.2 mg/dL with BK viremia. The three patients with persistent viremia displayed renal insufficiency; one of them died due to multiorgan failure of unknown origin. Conclusions. BKV is frequently detected in OLT recipients (viruria 21% and viremia 18%) early after transplantation. It is more common among patients with rejection episodes. Persistent BK viremia may be related to renal dysfunction in OLT patients.