BK Virus After Kidney Transplantation: A Review of Screening and Treatment Strategies and a Summary of the Massachusetts General Hospital Experience.

BK virus (BKV) is a common infection encountered after kidney transplantation. BKV is associated with a spectrum of manifestations, starting with sub-clinical viruria, followed by viremia and BKV-associated nephropathy. Standard of care includes routine post-transplant screening for BK viruria and/or viremia. Both the Kidney Disease Improving Global Outcomes and the American Society of Transplantation Infectious Diseases Community of Practice have published screening recommendations. Although they vary slightly, they both highlight the importance of early detection with serial screening. Once BK viremia is detected, the standard management approach includes a reduction of immunosuppression. Guidelines differ slightly about the sequence of the immunosuppression reduction, but the end result is the same: lowering the overall immunosuppressive burden in the patient with BKV infection. At the Massachusetts General Hospital, from 2007 to 2009, there was no BKV screening protocol in place. The rate of screening during this time period increased from 62% to 81%. A total of 29 of the 243 patients were diagnosed with BK viremia (11.9%), with 23 identified as a result of screening and 6 as a result of testing for graft dysfunction. We developed a BKV screening protocol consisting of BKV polymerase chain reaction testing in blood starting 2 months after kidney transplantation and every 2 months thereafter, continuing through month 24 regardless of the allograft function. Additional screening for 6 more months is performed in patients who receive anti-lymphocyte globulin for the treatment of acute rejection. Finally, all patients with otherwise unexplained allograft dysfunction are screened. Currently, work is being done investigating the use of mammalian target of rapamycin inhibitors to treat BKV infection. Trials are also ongoing evaluating cell-based therapies for BKV. Research to develop a vaccine or a direct-acting antiviral agent is in critical need and an area of research that should be given high priority.