Management and outcome of BK viremia in renal transplant recipients: a prospective single-center study

Transplantation. 2012 Oct 27;94(8):814-21. doi: 10.1097/TP.0b013e31826690c6.


Background: BK viremia can lead to nephritis, which can progress to irreversible kidney transplant failure. Our prospective study provides management and outcome of BK viremia in renal transplant recipients.

Methods: Two hundred forty de novo kidney-only recipients were enrolled from July 2007 to July 2010 and followed for 1 year. Standard immunosuppression with Thymoglobulin/interleukin 2 receptor blocker and mycophenolate mofetil/tacrolimus (Tac)/prednisone was employed. Quantitative BK virus (BKV) DNA surveillance in plasma/urine was performed at 1, 3, 6, 12, and 24 months after transplantation. Patients with significant viremia (defined as ≥10,000 viral copies/mL) underwent renal biopsy and treated with 30% to 50% reduction in doses of both mycophenolate mofetil and Tac without antiviral therapy. The target 12-hr Tac trough levels were lowered to 4 to 6 ng/mL in the significant viremia group, whereas the target levels remained unchanged at 5 to 8 ng/mL for all other groups.

Results: Sixty-five patients (27%) developed BK viremia; 28 (12%) of whom had significant viremia. A total of five (21%) of the 23 (of 28) patients who underwent biopsy presented with subclinical BKV nephritis. The mean plasma BKV DNA declined by 98% (range, 76%-100%) at 1 year after peak viremia. Acute cellular rejection seen in four (14%) of 28 patients, responded to bolus steroids. There was no decline in estimated glomerular filtration rate over time from 1 month after transplantation to 1 year after peak viremia (P=0.57).

Conclusion: Reduction in immunosuppression alone resulted in the successful resolution of viremia with preservation of renal function and prevention of clinical BKV nephritis and graft loss.

MeSH terms

  • Adult
  • Aged
  • BK Virus / isolation & purification*
  • Biopsy
  • Female
  • Humans
  • Kidney / pathology
  • Kidney Transplantation / adverse effects*
  • Male
  • Middle Aged
  • Mycophenolic Acid / administration & dosage
  • Mycophenolic Acid / analogs & derivatives
  • Nephritis / prevention & control
  • Polyomavirus Infections / drug therapy*
  • Postoperative Complications / drug therapy*
  • Prospective Studies
  • Tacrolimus / administration & dosage
  • Treatment Outcome
  • Tumor Virus Infections / drug therapy*
  • Viral Load
  • Viremia / diagnosis
  • Viremia / drug therapy*
  • Viremia / virology


  • Mycophenolic Acid
  • Tacrolimus