Polyomavirus BK nephropathy Fabrizio Ginevri Kidney Transplantation Unit, Department of Nephrology, Istituto G. Gaslini, Genova, Italy

BKV infection: the virus DNA virus that belongs to the polyomaviridae family: Polyomavirus BK Polyomavirus JC SV40 New: Polyomavirus KI, Polyomavirus WU, Polyomavirus MC Structure: The BKV genome comprises three regions: 1. the NCCR 2. the structural region coding for early T proteins 3. the late structural region encoding the viral capsid proteins (VP1-3) and agnoprotein

BKV infection: the virus Infects up to 90% of the general population Transmitted via aerosol, urinary shedding, allograft After primary infection, renal tubular epithelial cells and the urothelial cell layer represent the principal sites of viral latency or replication BKV disease is rare, and almost invariably associated with an immunodeficiency status

BKV infection after kidney transplantation Reactivation/primary infection in KTx recipients: asymptomatic infection ureteral stenosis systemic vasculopathy interstitial nephropathy (BKVN): increased prevalence of BKVN in the last decade (from 1% in 1995 to 5-10% in 2001) the majority of cases occur within the 1st year after Tx, but at least 25% of cases are diagnosed later 10-80% graft loss: but, with increased awareness and improved diagnostic techniques, the rate of graft loss has lowered

BKV nephropathy after kidney Tx: risk factors Patient determinants age>50 yrs male gender diabetes negative recipient serostatus before Tx Organ determinants degree of HLA-matching prior rejection episodes renal tissue injury positive donor serostatus before Tx Viral determinants genome mutation and rearrangements Immune suppression major risk factor for BKVN: it is plausible that a state of “over-immunosuppression”, rather than a specific agent is responsible for an increased risk of BKVN development

BKV nephropathy after kidney Tx: pathogenesis Immunosuppression load: triple vs. double therapy Binet et al. Transplantation 1999 Hirsch et al. Transplantation 2005 Renal injury + organ BK load BKV mutations PVAN  BKV replication BKV-mediated tissue damage + Lack of immune memory: BK seronegativity Ginevri et al. Transplantation 2003 Smith et al. Am J Transplant 2004 Failure of immune surveillance

Analysis of BKV-specific immunity after KTx: parameters correlated with protection from BK viruria IFN-g secreting cells cytotoxicity 300 50 VP1 VP1 225 37,5 SFU/105 cells % specific lysis 150 25 75 12,5 N U+/U+P+ N U+/U+P+ 50 LT 300 LT p<0.05 * p<0.005 ** 37,5 225 % specific lysis SFU/105 cells 25 150 75 12,5 N U+/U+P+ N U+/U+P+ Ginevri F, Comoli P, et al. manuscript in preparation

Analysis of BKV-specific immunity after KTx: parameters correlated with protection from BK viremia IFN-g secreting cells SFU/105 cells LT 166 333 500 U+_pre U+_peak U+P+_pre U+P+_peakU p=0.07 Ginevri F, Comoli P, et al. manuscript in preparation

Approach to screening for BKVN diagnosis Ginevri F, Hirsch HH. BK polyomavirus nephropathy. 2008

BKV nephropathy after KTx: diagnosis BKVN has a focal presentation as a consequence, negative biopsy results cannot rule out BKVN with certainty Histological patterns A Viral cytopathic changes only, in near-normal renal parenchyma. B Combination of viral cytopathic changes and focal/multifocal areas of tubular atrophy/interstitial fibrosis/ inflammation C Very scarce viral cytopathic changes in diffusely scarred renal tissue. Extensive tubular atrophy/interstitial fibrosis /inflammation involving all the tissue core with no residual areas of non atrophic tubules. Drachenberg et al. Hum Path 2005; 36:1245

Screening for BKVN and therapeutic intervention Ginevri F, Hirsch HH. BK polyomavirus nephropathy. 2008

Treatment of “definitive” BKVN The therapeutic mainstay is reduction of maintenance immunosuppression Antivirals and other pharmacologic approaches have been variably associated Ginevri F, Hirsch HH. BK polyomavirus nephropathy. 2008

Treatment of “definitive” BKVN: results Early diagnosis has allowed a significant amelioration of prognosis graft outcome: no screening: 35-50% of BKVN treated with any protocol  marked graft dysfunction, with possible progression to graft loss; screening and early treatment: no graft loss, milder graft dysfunction. Ginevri F, Hirsch HH. BK polyomavirus nephropathy. 2008

Preemptive treatment of BKVN On the basis of plasma BKV-DNA analysis DNA threshold for treatment: >104 ge/ml graft outcome: viremia clearance, no BKVN, no acute rejection Ginevri F, Hirsch HH. BK polyomavirus nephropathy. 2008

BKVN prospective monitoring and preemptive treatment after pediatric KTx 62 pediatric KTx recipients referred between 01/02 and 08/05: Group 1: BKV-sero+ patients, that did not reactivate after Tx Group 2: patients with positive viruria after Tx Group 3: patients with positive viruria and viremia after Tx Prospective monitoring of BKV DNA, measured by Q-PCR, in urine and plasma. +1, +3, +6, +9, +12, +18, +24, >24 months after KTX 0.0 0.2 0.4 0.6 0.8 1.0 12 24 36 48 60 MONTHS AFTER TRANSPLANTATION CUMULATIVE INCIDENCE (95% CI) Viruria: 64% (53-78) Viremia: 22% (13-35) Viruria: N = 62; E = 39 Viremia: N = 62; E = 13 Number of patients at risk: 62 42 36 21 11 0 Ginevri et al. Am J Transplant 2007

Results: effect of IS reduction on viral load and outcome Ginevri et al. Am J Transplant 2007

Reconstitution dynamics of BKV-specific immunity after preemptive treatment IFNg-secreting cells 266 533 800 Pre-BK viremia BK viremia increase decrease Post-BK clearance Spots/105 cells VP1 LT ** * Sero+ controls KTx-r no BKV Ginevri et al. Am J Transplant 2007

Reconstitution dynamics of BKV-specific T cells and serology in a patient with BKVN Comoli, Ginevri, Hirsch. Transplant Infect Dis 2006

Monitoring of specific immunity in patients with BK viremia Modulation of IS reduction according to cellular immunity analysis 100 200 300 400 103 104 105 106 1 2 3 0.5 4 6 9 12 IFN-g SFU/105  VP1  LT Plasma BKV load Months post-Tx Comoli P, Hirsch HH, Ginevri F. Curr Opin Organ Transplant 2008

BKVN after KTx: conclusions and open issues Outcome of BKVN when BKVN is advanced (stages B2-3 and C), outcome is still suboptimal early treatment (stages A and B1) yields better results in terms of graft outcome preemptive treatment on the basis of BK viremia seems at present the best option, but screening protocol has to be defined Long term outcome of allografts after BKV infection data on long-term allograft outcome after successful treatment for BKVN are scarce. However, preliminary results suggest that BKVN is a risk factor for progressive chronic allograft dysfunction direct virus damage ? suboptimal IS ? In case of prevalent direct damage, preemptive treatment may allow to reduce considerably the risk of progressive allograft failure In the second instance, tailoring of preemptive treatment on the basis of viremia and specific immune reconstitution may avoid excess IS reduction, and thus suboptimal IS

A Parodi E Verrina Pediatric Kidney Tx Program Genova, Italy Pediatric Hematology/Oncology Fondazione Policlinico S. Matteo, Pavia, Italy P Comoli S Basso A Gurrado Pediatric Kidney Tx Program Genova, Italy Pediatric Nephrology Istituto G. Gaslini F Ginevri A Parodi E Verrina M Cioni G Barbano Department of Transplantation Ospedale S Martino I Fontana U Valente Department of Public Health Università di Firenze, Italy A Azzi Department of Transplantation Virology University of Basel, Switzerland H H Hirsch Pediatric Kidney Disease Fund Genova, Italy R Gusmano

Retransplantation Retransplantation is a feasible option after graft loss to PAN : PAN recurrence in 2/13 reported patients (15%) In the absence of active BKV infection Nephrectomy of the original graft may not be necessary Baseline IS: does not need to be specifically adjusted In case of failure to reduce viral load or when IS reduction is contraindicated, the administration of antiviral drugs (e.g. cidofovir) and/or the surgical removal of the alloureter and kidney could be considered Post-transplant follow-up management Monitor: urine/plasma viral load general/specific immunity Therapeutic intervention guided by plasma DNA levels