From the Guidelines
BK polyomavirus infection is a significant concern in immunocompromised patients, particularly kidney transplant recipients, as it can lead to BK virus nephropathy, potentially causing kidney dysfunction and transplant failure. The virus can remain dormant in healthy individuals but can reactivate in immunosuppressed patients, highlighting the importance of regular monitoring and early detection. Key aspects of management include:
- Reducing immunosuppression as the first-line approach, typically by decreasing or eliminating mycophenolate mofetil while maintaining adequate tacrolimus or cyclosporine levels, as suggested by the KDIGO clinical practice guideline 1.
- Considering antiviral treatments such as cidofovir or leflunomide for persistent or severe cases.
- Regular monitoring of viral load through PCR testing of blood and urine, with screening recommended 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, as outlined in the KDIGO guideline 1. The significance of BK polyomavirus infection stems from its ability to cause disease in immunocompromised patients, particularly kidney transplant recipients, and the importance of balancing viral replication with the host's immune response, which is compromised by immunosuppressive medications necessary to prevent organ rejection, as discussed in the American Society of Transplantation recommendations 1. Reducing immunosuppressive medications when BKV plasma NAT is persistently greater than 10,000 copies/ml is a crucial step in managing the infection, as suggested by the KDIGO guideline 1. Overall, early detection and intervention are crucial in preventing the progression of BK polyomavirus infection to BK virus nephropathy and potential transplant failure.
From the Research
Significance of BK Polyomavirus Infection
The significance of BK polyomavirus (BKPyV) infection can be understood through its impact on kidney transplant recipients. Key points include:
- BKPyV is a common human polyomavirus that rarely causes clinical symptoms in immunocompetent individuals, but can reactivate in kidney transplant patients, leading to BK virus-associated nephropathy (BKVN) and reduced kidney allograft survival 2.
- BKPyV reactivation occurs in 20-40% of kidney transplant patients, and 1-10% of cases present with BKVN 2.
- The virus can cause nephropathy, ureteral stenosis, and hemorrhagic cystitis in kidney transplant recipients, making it an important emerging disease in transplantation 3.
Clinical Management and Screening
Clinical management and screening strategies for BKPyV infection are crucial for preventing graft failure. Key points include:
- Regular screening for BKPyV reactivation, mainly during the first 2 years post-transplant, with subsequent pre-emptive reduction of immunosuppression, is considered the best option to avoid disease progression 3.
- Screening techniques include plasma and urine assays for detection of BK virus DNA by PCR, urine cytology for detection of "decoy cells", and electron microscopy 4.
- International experts recommend screening all kidney transplant recipients monthly for plasma BKPyV-DNAemia loads until month 9, then every 3 months until 2 years post-transplant 5.
Treatment and Outcomes
Treatment and outcomes of BKPyV infection are critical for graft survival. Key points include:
- Reduction of immunosuppression is the most important preferred treatment approach for BKVN, with additional treatments such as leflunomide, intravenous immunoglobulin, and cidofovir being used in some cases 6.
- Intensive treatment protocols for BKVN, including combined treatment with leflunamide + IVIG together with immunosuppressive dose reduction, can be an effective approach to prolong graft survival 6.
- Allograft biopsies should be interpreted in the context of all clinical and laboratory findings, including plasma BKPyV-DNAemia, and immunohistochemistry is preferred for diagnosing biopsy-proven BKPyV-nephropathy 5.