Table of contents
BK polyomavirus-associated nephropathy
What's new
Added 2024 TTS and 2019 AST guidelines for the diagnosis and management of BK polyomavirus-associated nephropathy.
Background
Overview
Definition
BKPyV-nephropathy is a kidney disease caused by the BKPyV, which generally results in asymptomatic infections but can cause severe complications in immunocompromised patients, especially kidney transplant recipients.
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Pathophysiology
The pathophysiology of BKPyV-nephropathy involves the reactivation of BKPyV in renal tubular cells and the uroepithelium, leading to viral replication and immune-mediated tissue damage. BKPyV-encoded microRNAs have been shown to control viral replication and assist in immune evasion.
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Epidemiology
BKPyV viremia and BKPyV-nephropathy are reported to affect 10-20% and 1-10% of kidney transplant recipients, respectively.
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Risk factors
Risk factors for BKPyV-nephropathy include intense immunosuppression, HLA mismatches, prior rejection and anti-rejection treatment, and BKPyV-seropositive donor/seronegative recipient pairs.
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Disease course
The clinical course of BKPyV-nephropathy is characterized by the progression from asymptomatic BKPyV reactivation to overt nephropathy, most commonly 2-6 months after transplantation.
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Prognosis and risk of recurrence
The prognosis of BKPyV-nephropathy is generally poor, with graft loss occurring in > 50% of cases. However, early detection and reduction of immunosuppression can significantly improve outcomes, reducing graft loss to < 10% of cases.
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Guidelines
Key sources
The following summarized guidelines for the evaluation and management of BK polyomavirus-associated nephropathy are prepared by our editorial team based on guidelines from the Transplantation Society (TTS 2024), the American Society of Transplantation (AST 2019), and the Kidney Disease: Improving Global Outcomes Foundation (KDIGO 2009).
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Screening and diagnosis
Pre-transplant testing
As per AST 2019 guidelines:
Do not obtain testing for genetic markers, BKPyV viruria, virus genotyping, or BKPyV virus-like particles/VP1-specific-specific antibody levels in kidney transplant donors before transplantation.
D
Do not obtain testing for genetic markers, BKPyV virus-like particles/Vp1-specific antibody levels, or BKPyV (subtype)-neutralizing antibody levels, or BKPyV‐specific T‐cell quantity or function in kidney recipients before kidney transplantation.
D
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Indications for screening (kidney transplant recipients)
Indications for screening (non-kidney transplant recipients)
Diagnostic investigations
NAATs: as per TTS 2024 guidelines, use quantitative nucleic acid testing assays targeting conserved BKPyV genome sequences to allow the detection of all genotypes and variants.
B
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Donor-specific antibodies
Evaluation for JC polyomavirus‐associated nephropathy
Diagnostic procedures
Renal biopsy: as per TTS 2024 guidelines, perform kidney biopsy as clinically indicated (such as increased serum creatinine, proteinuria, hematuria) in patients with detectable BKPyV-DNAemia.
A
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Histopathology
Medical management
Reduction of immunosuppression, general principles: as per TTS 2024 guidelines, consider confirming that all immunosuppressive drug doses and concentrations are within the institutional target range.
C
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Reduction of immunosuppression (antimetabolite first)
Reduction of immunosuppression (calcineurin inhibitor first)
Reduction of immunosuppression (mTOR inhibitors)
Reduction of immunosuppression (belatacept)
Adjunctive therapies
Management of acute rejection
Surgical interventions
Specific circumstances
Pediatric patients: as per TTS 2024 guidelines, obtain monthly screening for plasma BKPyV-DNAemia in pediatric kidney transplant recipients until 9 months post-transplantation, then every 3 months until 24 months post-transplantation.
B
consider continuing screening every 3 months until 36 months post-transplantation. B
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