From the Guidelines
BKV, or BK virus, is a significant concern in immunosuppressed patients, particularly those who have received organ transplants, and requires regular screening and monitoring to prevent BK virus nephropathy and other complications. BKV is a polyomavirus that remains dormant in most healthy individuals but can reactivate when the immune system is suppressed. In immunosuppressed patients, BKV can cause BK virus nephropathy in kidney transplant recipients, leading to graft dysfunction and potential graft loss, or hemorrhagic cystitis in bone marrow transplant recipients.
Key Considerations
- Management typically involves reducing immunosuppression when possible, as there are no specific antiviral treatments approved for BKV.
- Regular screening for BKV reactivation through blood and urine tests is recommended for high-risk patients, especially in the first year post-transplant, with a suggested screening frequency of at least monthly for the first 3-6 months after transplantation, then every 3 months until the end of the first post-transplant year, and whenever there is an unexplained rise in serum creatinine 1.
- Some centers use cidofovir, leflunomide, or intravenous immunoglobulin as adjunctive therapies, though evidence for their efficacy is limited 1.
- Prevention focuses on careful immunosuppression management, balancing the need to prevent rejection while minimizing the risk of viral reactivation.
Monitoring and Screening
- Quantitative plasma nucleic acid testing (NAT) is recommended for screening all kidney transplant recipients for BKV, with a suggested threshold for reducing immunosuppressive medications when BKV plasma NAT is persistently greater than 10,000 copies/ml 1.
- Laboratory evaluation should also be done for any unexplained rise in serum creatinine and should include a urinary and peripheral blood BK PCR and biopsy tissue immuno-staining or in situ hybridization for BK virus 1.
Treatment and Management
- Reducing immunosuppressive medications is the primary approach to managing BKV reactivation, with the goal of preventing BK virus nephropathy and other complications.
- Supportive care remains the mainstay of management for BK virus reactivation, with a focus on individualized management and close monitoring of patients 1.
From the Research
Definition of BKV
- BKV stands for BK virus, a type of polyomavirus that can cause infection in immunosuppressed individuals, particularly those who have undergone kidney transplantation 2.
- The virus is usually latent in healthy adults, but can reactivate in immunocompromised patients, leading to complications such as nephropathy (BKVN) 2.
Risk Factors for BKV Infection
- Overimmunosuppression is a significant risk factor for BKV infection, particularly with the combination of tacrolimus, mycophenolate mofetil (MMF), and steroids 3.
- Other risk factors include retransplantation, panel-reactive antibody more than 0%, cytomegalovirus D+/R-, cold ischemia time, delayed graft function, induction with antithymocyte globulins, and acute rejection before month 3 (M3) 3.
- Elevated tacrolimus trough levels and high mycophenolic acid exposure have also been linked to an increased risk of BKV infection 3.
Management and Treatment of BKV Infection
- The mainstay approach to BK infection is reduction of immunosuppression, which can result in clearance of the virus and good long-term outcomes 4.
- Alterations in immunosuppressive regimen, such as minimization of calcineurin inhibitors and use of mechanistic target of rapamycin inhibitors, have been attempted with variable outcomes 5.
- Other potential therapeutic options for BK infection include fluoroquinolone prophylaxis, cidofovir, intravenous immunoglobulin, and virus-specific T cell therapy 5.
Clinical Implications of BKV Infection
- BKV infection can lead to significant clinical complications, including nephropathy (BKVN) and allograft loss 2.
- The disease may result in allograft loss in 45-70% of patients, highlighting the need for early diagnosis and effective management 2.
- Reducing immunosuppression can effectively treat BK viremia and BK nephropathy, but may be associated with increased risks for acute rejection and development of donor-specific antibodies (DSA) 6.