1. Challenges in Managing BKP Virus in Renal Transplantation

2. BKP Infection and RT
Polyomavirus infection in kidney transplant recipients is of increasing interest and research
Nephropathy from BK virus infection is an evolving challenge in kidney transplant recipients
It is the consequence of modern potent immunosuppression aimed at reducing acute rejection and improving allograft survival
Untreated BKV infections lead to kidney allograft dysfunction or loss
Clin J Am Soc Nephrol 2007;2: S36–S46,

3. Type and prevalence of BKV infections in kidney transplant recipients
Clin J Am Soc Nephrol 2007;2: S36–S46,

4. BK Polyomavirus RL28 Viral Infection in Organ Transplantation
CME Review Version
September 1, 2005
BK Polyomavirus 4

5. RL28 Viral Infection in Organ Transplantation
CME Review Version
September 1, 2005
BK Polyomavirus
JC virus (agent of progressive multifocal leukoencephalopathy) and SV40 in same family
Common viral infection with latency in uroepithelium, and in other tissues
Associated with sterile pyuria, ureteral ulceration and obstruction, hemorrhagic cystitis, parenchymal scarring in renal transplant recipients—rise in serum creatinine termed “BK nephropathy”
Causes hemorrhagic cystitis in BMT/HSCT; asymptomatic viruria in 10% to 45% of renal transplant recipients; disease (BK nephropathy) in 2% to 4% of all renal transplant recipients, but uncommon in extrarenal transplant recipients
The polyomaviruses exist as latent infection in many tissues, with the distribution determined by the cellular receptors needed for entry. As a result, it is likely that the spectrum of disease is broader than is currently recognized. BK nephropathy is a progressive viral infection characterized by scarring of the renal parenchyma. This disease is uncommon in recipients of extrarenal organ transplants, possibly because of the synergy of ischemia-reperfusion injury, warm and cold ischemia, and drug toxicity in the renal allograft.
Binet I, Nickeleit V, Hirsch HH, et al. Polyomavirus disease under new immunosuppressive drugs: a cause of renal graft dysfunction and graft loss. Transplantation. 1999;67:
McGilvray ID, Lajoie G, Humar A, Cattral MS. Polyomavirus infection and acute vascular rejection in a kidney allograft: coincidence or mimicry? Am J Transplant. 2003;3:
Nickeleit V, Hirsch HH, Binet IF, et al. Polyomavirus infection of renal allograft recipients: from latent infection to manifest disease. J Am Soc Nephrol. 1999;10:
BMT, bone marrow transplant; HSCT, hematopoietic stem cell transplantation.
Binet I et al. Transplantation. 1999;67: ; McGilvray ID et al. Am J Transplant. 2003; 3: ; Nickeleit V et al. J Am Soc Nephrol. 1999;10: 5

7. RL28 Viral Infection in Organ Transplantation
CME Review Version
September 1, 2005
BK Nephropathy
50% of BK nephritis in first 3 months posttransplantation
May coexist with rejection—may be exacerbated by corticosteroid boluses (possible role of corticosteroid- responsive element in promoter)
Linked to intensity of immune suppression (not specific agents)
The risk for BK nephropathy appears to be related to the intensity of immune suppression. Most cases occur within the first 6 months after renal transplantation, and often following pulse-dose steroids for presumed graft rejection. BK nephropathy is rare, but not impossible, in non-renal transplant recipients. The prime observation is a rise in serum creatinine levels of renal transplant recipients without another explanation – (eg, rejection, drug toxicity, technical problems). Patients with BK nephropathy may have “sterile pyuria” – usually small numbers of cells in the urine including tubular epithelial cells.
Mylonakis E, Goes N, Rubin RH, Cosimi AB, Colvin RB, Fishman JA. BK virus in solid organ transplant recipients: an emerging syndrome. Transplantation. 2001;72:
Drachenberg RC, Drachenberg CB, Papadimitriou JC, et al. Morphological spectrum of polyoma virus disease in renal allografts: diagnostic accuracy of urine cytology. Am J Transplant. 2001;1:
Gardner SD, MacKenzie EF, Smith C, Porter AA. Prospective study of the human polyomaviruses BK and JC and cytomegalovirus in renal transplant recipients. J Clin Pathol. 1984;37:
Ramos E, Drachenberg CB, Papadimitriou JC, et al. Clinical course of polyoma virus nephropathy in 67 renal transplant patients. J Am Soc Nephrol. 2002;13:
Mylonakis E et al. Transplantation. 2001;72: ; Drachenberg RC et al. Am J Transplant. 2001;1: ; Gardner SD, et al. J Clin Pathol. 1984; 37: ; Ramos E, et al. J Am Soc Nephrol 2002; 13: 7

8. A typical tubular cell infected by polyoma virus BK

11. RL28 Viral Infection in Organ Transplantation
CME Review Version
September 1, 2005
BK Virus: Diagnosis
Urine cytology is highly sensitive (but not specific) for screening: urine decoy cells (cytology)
Tissue biopsy needed for confirmation
Histology: tubular injury, cellular enlargement, inflammation, intranuclear and intracytoplasmic inclusion bodies (exclude rejection, PTLD)
Electron microscopy: intracellular crystalline arrays
Nucleic acid hybridization in situ
PCR (blood): higher incidence of viremia in symptomatic patients; many asymptomatic – but not diagnostic
Urine cellular PCR (VP1 mRNA): 6 x 105 copies/ng1
Urine cytology looking for “decoy cells” is the most sensitive screening test for the presence of BK nephropathy; however, it is non-specific. Other tests for virus in blood or urine may be useful in the determination of risk for disease or to follow a course of therapy. Diagnosis is dependent on the demonstration of appropriate tissue histology with tubular injury, intracellular inclusions, and immuno-stains for BK virus (cross reacts with antibodies to SV40 large T antigen) or demonstration of virus by electron microscopy.
Ding R, Medeiros M, Dadhania D, et al. Noninvasive diagnosis of BK virus nephritis by measurement of messenger RNA for BK virus VP1 in urine. Transplantation. 2002;74:
PTLD, posttransplant lymphoproliferative disorder; PCR, polymerase chain reaction, 1. Ding R et al. Transplantation. 2002;74: 11

12. Urine cytology

13. Urine cytology

15. BK Virus: Mononuclear Infiltrate With Nuclear Inclusions
RL28 Viral Infection in Organ Transplantation
CME Review Version
September 1, 2005
BK Virus: Mononuclear Infiltrate With Nuclear Inclusions
Renal allograft biopsy
9 months post–deceased-donor transplantation demonstrating BK nephropathy
Serum creatinine levels rose to 2.4 mg/dL in this patient treated with tacrolimus and mycophenolate mofetil. On hematoxylin and eosin stain, many tubular epithelial nuclei are enlarged, with large lavender homogeneous inclusions; a mild mononuclear infiltrate is seen in the interstitium and occasionally in tubules. 15

16. BK Virus: Immunoperoxidase Stain for SV-40 Large T Antigen
RL28 Viral Infection in Organ Transplantation
CME Review Version
September 1, 2005
BK Virus: Immunoperoxidase Stain for SV-40 Large T Antigen
Immunohistochemical stain for polyomavirus shows prominent nuclear staining in several tubules (immunoperoxidase stain, monoclonal antibody to SV-40 large T antigen). 16

18. Noninvasive tests for BKV nephropathya
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19. Immunohistochemistry shows characteristic nuclear staining isolated to the medulla

20. Histologic patterns of BKV nephropathy
Clin J Am Soc Nephrol 2007;2: S36–S46,

21. BK Virus: Therapy No specific therapy at present
RL28 Viral Infection in Organ Transplantation
CME Review Version
September 1, 2005
BK Virus: Therapy
No specific therapy at present
Reduction in immune suppression results in graft loss of 16.4% to 80%; many maintain serum creatinine levels at ~2.5 mg/dL
Low-dose cidofovir has anecdotal successes and failures but may cause renal dysfunction
Some anecdotal experience with leflunomide (unapproved, no prospective trials), an immunosuppressive agent for rheumatologic disease with antiviral activity for BK and herpesviruses
Some anecdotal experience with later-generation fluoroquinolones
There is no specific therapy at present. Reduction in immune suppression may provoke graft rejection but may reduce viral load and stabilize renal function. Cidofovir is nephrotoxic and unapproved for this indication but is advocated by some practitioners. Other therapies are under investigation also including fluoroquinolone antimicrobial agents and leflunomide – an immunosuppressive agent with some antiviral activities.
Ramos E, Vincenti F, Lu WX, et al. Retransplantation in patients with graft loss caused by polyoma virus nephropathy. Transplantation. 2004;77:
Vats A, Shapiro R, Singh Randhawa P, et al. Quantitative viral load monitoring and cidofovir therapy for the management of BK virus-associated nephropathy in children and adults. Transplantation. 2003;75:
Poduval RD, Meehan SM, Woodle ES, et al. Successful retransplantation after renal allograft loss to polyoma virus interstitial nephritis. Transplantation. 2002;73:
Ramos E et al. Transplantation. 2004;77: ; Vats A et al. Transplantation. 2003; 75: ; Poduval RD et al. Transplantation. 2002;73: 21

22. Treatment Strategies
The principal treatment for BKV nephropathy is reduction in immunosuppression.
Various strategies include reduction or discontinuation of the calcineurin inhibitor and/or adjuvant agent, changing from MMF to azathioprine, sirolimus, or leflunomide or from tacrolimus to cyclosporine
Importantly, BKV nephropathy seems to develop less frequently with maintenance protocols that involve steroid withdrawal
When BKV nephropathy is diagnosed early within the first 6 mo after transplantation and the creatinine is stable, survival is improved compared with when the diagnosis is made later and the creatinine is elevated.
Daniel L. et al. Clin J Am Soc Nephrol 2007;2: S36–S46

23. Early or Presumptive BKV Nephropathy
Reduction in immunosuppression to clear the infection is balanced against the risk for precipitating acute or chronic rejection
Preemptive withdrawal of the antimetabolite upon detection of viremia prevents BKV nephropathy without significantly increasing the risk for rejection.
A step-wise reduction in MMF plus reduction in tacrolimus or conversion to cyclosporine.
Brennan DC et al Am J Transplant 5: 582–594, 2005,
Buehrig CK et al. Kidney Int 64: 665–673, 2003,

24. Impaired immune suppression balance
Impaired immune suppression balance. Inadequate immune suppression results in rejection, whereas excessive immune suppression results in BKV nephropathy. Both conditions present as allograft dysfunction with tubulointerstitial nephritis and progression to fibrosis.

25. Late BKV Nephropathy
Diagnosis of BKV nephropathy in the setting of allograft dysfunction often indicates more severe histologic changes, and renal function may only stabilize or may continue to progress despite treatment
Also, not treating or inadvertently treating with an antilymphocyte antibody often will lead to progression of disease (96).
Whether to reduce or discontinue one or more components of the maintenance regimen is not clear
No difference in graft survival whether immunosuppression wasreduced or continued or between reduction and discontinuation of tacrolimus or MMF among recipients with BKV nephropathy
Daniel L. et al. Clin J Am Soc Nephrol 2007;2: S36–S46

26. Adjuvant Therapies
On the basis of in vitro activity against BKV, treatment options for BKV nephropathy are
cidofovir,
quinolones, and
intravenous Ig (IVIG)
Daniel L. et al. Clin J Am Soc Nephrol 2007;2: S36–S46

27. Cidofovir
Cidofovir, a cytosine analogue and viral DNA polymerase inhibitor, inhibits BKV replication, mechanism is unclear
Cidofovir restores the function of p53 and pRB, targets of the large T antigen, and permit BKV-infected cells to undergo apoptosis
Cidofovir dose range for BKV nephropathy : 0.25 to 1 mg/kg every 1 to 3 wk
Cidofovir is used in conjunction with immunosuppression reduction
Cidofovir should be used with caution, frequent monitoring, and informed consent because of the potential complications
De Clercq E.Clin Microbiol Rev 16: 569–596, 2003 , Daniel L. et al. Clin J Am Soc Nephrol 2007;2: S36–S46

28. Quinolones Quinolones, DNA gyrase inhibitors
Interfere with the large T antigen helicase activity and have in vitro and in vivo activity against BKV (112–114).
Two months after a 10-d course of gatifloxacin, seven of 10 recipients with active BKV replication had reduction in viremia or urinary decoy cells
Thamboo et al. did not find improvement in viral clearance after a 10-d course of ciprofloxacin.
Leung AY et al Clin Infect Dis 40: 528–537, 2005, Randhawa PS et al Clin Infect Dis 41: 1366–1367, 2005, Chandraker A et al. Am J Transplant 4: 587, 2004, Stenlund A et al Nat Rev Mol Cell Biol 4: 777–785, 2003, Thamboo TP et al . J Clin Pathol December 8, 2006

29. IVIG
IVIG has been used for treatment for BKV nephropathy because of its immunomodulatory as well as potential anti-BKV properties
In combination with immunosuppression reduction, IVIG (2 to 3.5 g/kg over 2 to 7 d) treatment used as initial treatment for BKV nephropathy and BKV nephropathy with concurrent acute rejection
Because of the cost potential adverse effects and unproven efficacy, IVIG use for BKV nephropathy should be limited until controlled studies suggest benefit
Cibrik DM et al Am J Transplant 3:370, 2007, Sener A et al. Transplantation 81: 117– 120, 2006, Jordan SC et al Am J Transplant 6: 459–466, 2006, Orbach H et al. Clin Rev Allergy Immunol 29: 173–184, 2005

30. Screening
It is recommended that screening for BKV should be performed every 3 mo for the first 2 yr after transplantation,then annually through the fifth year, when allograft dysfunction occurs and when a transplant kidney biopsy is performed
Screening should be based on a urinary assay for decoy cells, BKV DNA, or BKV RNA. A positive screening test should be confirmed within 4 wk along with a quantitative assay.
Recipients with persistent high viral levels for 3 wk should undergo biopsy and intervention.
Monitoring should continue every 2 to 4 wk until the viral level falls below threshold values and preferably to undetectable levels.
Daniel L. et al. Clin J Am Soc Nephrol 2007;2: S36–S46

31. Screening protocol based on plasma BKV DNA PCR
Daniel L. et al. Clin J Am Soc Nephrol 2007;2: S36–S46

32. Conclusion-1
BKV nephropathy remains a significant posttransplantation complication.
Modern potent immunosuppressive medications have reduced acute rejection rates, improved early kidney allograft survival, and expanded the potential transplant population.
For an individual recipient, however, the increased immunosuppression may be excessive and predispose to BKV nephropathy
No clinical risk factors clearly identify the recipients who will develop BKV nephropathy.

33. Conclusion-2
BKV infection is an area of active investigation in kidney transplantation, much of the data are derived from retrospective case-control studies.
Prospective, randomized studies to address immunosuppression protocols, immune monitoring for BKV-specific and allospecific responses, and treatment protocols are needed.
Until reliable measures of immunosuppression or novel agents that specifically target BKV are available, BKV infections in kidney transplantation will remain a challenge