BK virus nephropathy in an immunodeficient patient with chronic lymphocytic leukemia

BACKGROUND

BK virus, genus polyomavirus, is known as an important cause of nephropathy (BKVN) in renal transplant patients. Cases of BKVN in native kidneys are rare.

OBJECTIVES

To report a case of BKVN in a patient with chronic lymphocytic leukemia (CLL) and to examine viral and immune parameters.

STUDY DESIGN

Quantitative BK virus DNA in plasma and relevant immune parameters were recorded in one CLL patient with BKVN and ten consecutive CLL patients without BKVN.

RESULTS

BKVN in the native kidneys of a CLL patient was histologically confirmed. The presence of BKVN correlated with immunologic parameters as well as factors known to cause renal tissue injury. BK viral load levels in the patient steadily increased and exceeded those of the control CLL patients.

CONCLUSIONS

The results document a pathogenic role for BK virus in native kidneys of immuno-compromised CLL patients and indicate a role for quantitative BK virus DNA detection for early management of BKVN in native kidneys.

Polyomavirus nephropathy: a current perspective and clinical considerations

During the last decade, the human polyomaviruses (BK virus and, much less commonly, JC virus) have entered the realm of routine clinical decision making for providers caring for kidney transplant recipients. The emergence of polyomavirus-associated nephropathy (PVAN) as an important clinical entity coincided with the development and use of more potent immunosuppression agents, currently the only clear risk factor for reactivation of the virus. Ongoing efforts to define the pathogenesis, clinical presentation, and appropriate management of PVAN have led to a greater ability to prevent and control viral-induced interstitial nephritis despite continued deficiencies in our understanding of risk factors for disease and lack of published prospective polyomavirus-specific antiviral trials. The purpose of this review is to summarize advances made during the last decade and highlight emerging data that address common clinical considerations the clinician currently faces in the understanding and management of PVAN.

BK virus nephropathy after allogeneic stem cell transplantation: a case report and literature review

Polyomaviruses are increasingly recognized as important human pathogens. Among those, BK virus has been identified as the main cause of polyomavirus-associated nephropathy (PVAN), a major cause of renal allograft failure. PVAN has also been well described in the setting of non-renal solid organ transplantation. The reports of PVAN after hematopoietic stem cell transplantation (HCT) are surprisingly very few. Here, we describe a patient with treatment-related myelodysplastic syndrome who received an unrelated donor HCT after ablative conditioning and in vivo T cell depletion with alemtuzumab. He developed a biopsy-proven BK nephropathy, which contributed to his renal failure. Leflunomide as well as cidofovir were given at different times, both in combination with intravenous immunoglobulin. Both treatments were effective in reducing the BK viral load, the cystitis symptoms and both stabilized but did not really improved the renal function. The patient was still dialysis-dependent when he died from Pseudomonas sepsis 13 months after HCT. A critical review of the literature and the treatment modalities for post-HCT PVAN are provided.

Risk factors for polyoma virus nephropathy

BACKGROUND

Polyoma virus-associated nephropathy (PVN) is a common cause of renal transplant failure. The risk factors for the development of PVN have not yet been studied in large cohorts of patients for periods of 20 years.

METHODS

We collected clinical, renal biopsy and urinary cytology data from all patients with renal transplantations performed at the University Hospital of Basel from 1985 to 2005. All patients with a renal biopsy and urine cytology were included (n = 880). Renal transplants were divided into three groups, according to evidence of polyoma virus (PV) infection (decoy cells in the urine) and biopsy-proven PVN: Renal transplants without evidence of a PV infection (n = 751). Renal transplants with PV reactivation, e.g. decoy cell (DC) found by urinary cytology, but without PVN (n = 90). Renal transplants with PVN (n = 39).

RESULTS

The prevalence of biopsy-proven PVN in this cohort of patients was 3.3%. Immunosuppression with mycophenolate and/or tacrolimus, ATGAM, male gender of the recipient and a higher number of transplant rejection episodes were factors significantly associated with PVN development.

CONCLUSIONS

The most important risk factors for the development of PVN are acute rejection and ATGAM used as induction therapy as well as tacrolimus and mycophenolate as maintenance therapy. Therefore, we conclude that patients with tacrolimus and mycophenolate maintenance therapy should be carefully monitored for the development of PVN.

Low-dose Cidofovir for the Treatment of Polyomavirus-Associated Nephropathy: Two Case Reports and Review of the Literature

Background

Polyomavirus-associated nephropathy (PVAN) is a serious complication and cause of graft loss in kidney transplant recipients. In the absence of specific antiviral drugs, early detection of the disease and reduction of immunosuppressive regimen is the cornerstone of therapy. Cidofovir, a nucleoside analogue, has been found to inhibit BK virus (BKV) replication in vitro and has been proposed as treatment of refractory PVAN at low doses; however, its efficacy has never been demonstrated in randomized controlled trials.

Methods

Cidofovir therapy (0.5 mg/kg at a 2-week interval for eight consecutive doses) was initiated in two patients with biopsy-proven PVAN and persistent BKV DNA viraemia (≥10,000 copies/ml despite sustained reduction of the immunosuppressive regimen). In addition to these two case reports, we performed a critical review of the literature on the use of cidofovir in PVAN.

Results

No significant decrease of BKV viral load in blood was observed during cidofovir therapy and in follow-up of the two patients treated with cidofovir. Our literature review identified 21 publications reporting the use of cidofovir for the treatment of PVAN. All were case reports or small series. The efficacy of cidofovir therapy could not be assessed in 17 of these publications because of lack of data or concomitant reduction of immunosuppressive regimen. The four remaining publications were case reports.

Conclusions

In vitro and clinical data to support the efficacy of cidofovir in the treatment of PVAN are currently lacking. More promising compounds should be identified for further clinical studies.

Prospective monitoring of BK polyomavirus infection early posttransplantation in nonrenal solid organ transplant recipients

BACKGROUND

BK virus-associated nephropathy is an important cause of renal dysfunction in renal transplant recipients. Renal dysfunction after nonrenal solid organ transplantation (NRSOT) is common; however, the impact of BK virus remains uncertain.

METHODS

Sixty (7 heart, 25 liver, and 28 lung) NRSOT recipients were enrolled in this single center prospective longitudinal study. Urine and plasma were collected for detection of BK viral load using a real-time quantitative polymerase chain reaction assay at transplantation and at 3, 6, and 9 months posttransplantation. Demographic and clinical data including serum creatinine and immunosuppressive therapy were also collected.

RESULTS

BK viruria was detected in 16 of 193 (8.3%) samples corresponding to 9 of 60 (15%) subjects. The median BK viral load was 1.12 x 10 (range, 1.1 x 10-2.66 x 10) copies per milliliter. No viremia was detected. In seven of nine, viruria occurred by 3 months posttransplantation. At 9 months of posttransplantation, the median Modification of Diet in Renal Disease-estimated glomerular filtration rate in those with BK viruria on at least one sample was similar to those without viruria (58.0 [IQR 43.1-60.7] mL/min/1.73 m vs. 61.4 [IQR 50.6-74.4] mL/min/1.73 m; P=0.39).

CONCLUSIONS

Although BK infection was common in this NRSOT population, BK viremia was not observed and there was no association between BK viruria and renal dysfunction. Our data suggest that routine surveillance for BK virus early posttransplantation in NRSOT may not be warranted but should be further examined in a larger multicenter trial.

BK virus nephropathy in renal transplant patients in London

BACKGROUND

BK nephropathy (BKN) is an important cause of renal transplant dysfunction, believed to be associated with higher levels of immunosuppression. We assessed the experience of BKN in renal transplant patients in the London region.

METHODS

All six London transplant centers participated and case notes of patients with BKN in 2004 to 2005 were reviewed.

RESULTS

There were 17 cases of BKN, giving an incidence of 2.1%. Median time to diagnosis was 9 months. Median baseline creatinine rose from 150 to 196 mumol/L. At diagnosis, 16 patients were on tacrolimus, 15 on mycophenolate mofetil, and 10 on triple therapy with tacrolimus, mycophenolate mofetil, and prednisolone. Management of BKN involved reducing immunosuppression; cidofovir was used in two patients and methylprednisolone in five for acute rejection. Median follow-up time was 29.2 months. Creatinine returned to baseline in four patients, remained elevated in 12 and one patient lost his graft. The new median baseline creatinine was 216 mumol/L. Eight patients underwent repeat biopsies of which four became negative for BKV and three subsequently cleared the virus on blood and urine polymerase chain reaction and urine decoy cells. Overall, eight patients cleared the virus. None of age, sex, viral load, or biopsy characteristics (Banff ct score, Drachenberg grade, and number of BKV positive cells) were associated with poorer outcome when patients with increase in creatinine of less than 30% (n=7) or more than 30% (n=10) from baseline were compared.

CONCLUSION

The incidence of BKN in this study is comparable with previous studies, with more favorable outcomes. It supports the association of BKN with potent immunosuppression.

Polyomavirus BK infection in blood and marrow transplant recipients

The association of BK virus infection with hemorrhagic cystitis in blood and marrow transplant (BMT) recipients was first demonstrated two decades ago. During this time, therapeutic interventions focused on supportive measures such as hyperhydration, continuous bladder irrigation and topical administration of agents that alter the mucosal surface of the bladder wall. In recent years, PCR amplification of viral DNA in the urine and plasma has solidified the association of BK virus infection with hemorrhagic cystitis, demonstrating that higher urine and plasma viral loads occur in the setting of disease. The evaluation of virus-specific therapy has lagged behind assessment of the viral load and theories of pathogenesis. Extrapolating from successes in the treatment of BK virus nephropathy in the renal transplant population, cidofovir and leflunomide are identified as potential effective agents for the treatment of BK virus-associated hemorrhagic cystitis. The fluoroquinolone antibiotics may prove to be effective as prophylactic agents. Given the manifestation of BK virus infection in organs outside of the urinary tract in an increasing immunocompromised patient population and the availability of potential antiviral agents, therapeutic trials need to progress beyond the small case series in order to improve the morbidity and mortality caused by BK virus-associated hemorrhagic cystitis in the BMT population.

Polyoma virus in pediatric renal transplantation

Renal transplantation is the treatment of choice for children with end-stage renal disease. Patient survival and allograft survival have improved with better immunosuppressant regimes to reduce acute allograft rejection but post-transplant infections have been exacerbated. An emerging problematic virus in the past decade is the polyoma virus BKV. The features of BKV including the clinical features in the general and immune compromised population are reviewed and correlated with pediatric studies in the post-transplant population. These features are placed in context with lessons learned about BKV in relevant adult studies.

Molecular and clinical perspectives of polyomaviruses: emerging evidence of importance in non-kidney transplant populations

JC virus (JCV), BK virus (BKV) and simian virus 40 (SV40) are deoxyribonucleic acid (DNA) viruses, members of the family Polyomaviridae. These viruses establish persistent infections, and reactivate from latency in their host under immunosuppression. During the last few years there has been recognition of the morbidity related to polyomaviruses, particularly BKV in kidney transplant recipients. More importantly, recent studies indicate the potential implication of JCV, BKV, and SV40 in renal dysfunction among nonrenal organ transplant patients. Polyomaviruses are tumor-inducing viruses and animal models have provided evidence of the oncogenicity of these pathogens. Although data are not conclusive, molecular studies suggest an association of BKV and SV40 with malignancies among solid organ transplant patients. As new and potent immunosuppressive agents are introduced into clinical practice, it is believed that the incidence of polyomavirus-related diseases in organ transplantation might increase. This review evaluates the biologic and epidemiologic features of these 3 viruses, the data regarding their infections in nonkidney organ transplant patients and describes future directions in the management and research of these opportunistic pathogens.

Renal Donor Implication in the Origin of BK Infection: Analysis of Genomic Viral Subtypes

BK virus (BKV) reactivation in immunocompromised kidney transplant patients can produce a tubulointerstitial nephropathy (BKVN). Molecular tools that test for DNA-BKV provide early detection and assist in management, but some aspects of the pathogenesis of this infection, such as donor causality, remain unclear.

MATERIALS AND METHODS

Between November 2004 and January 2006, 55 Spanish kidney donors were studied for BK infection. A quantitative PCR assay was performed on urine and serum to detect BKV. To determine the origin of the viral infection, a transcription control region of the BK polymorphism sequence was designed to identify the viral subtype.

RESULTS

Fifteen of 55 (27%) donors were BK-PCR positive: 13 in urine and 2 in serum and urine. Moreover, monitoring of recipient pairs detected BK-PCR positivity in 14 of 73 recipients. We studied eight BK-PCR positive recipients (corresponding to four pairs) and their respective donors. The same viral genome was observed in the four pairs, namely, the A250-1-a, WW-like, AS, and JL genotypes. Interestingly, one of the four pairs showed the donor and the two recipients to display exactly the same JL genotype.

CONCLUSION

On the basis of our preliminary results analyzing the molecular fingerprints of donor and recipient pairs, we have presented new data implicating the donor, in at least some cases, as the source of BK infection.

Isolated heart and liver transplant recipients are at low risk for polyomavirus BKV nephropathy

BACKGROUND

BKV infection and nephropathy is a significant cause of allograft dysfunction in kidney transplantation. BKV viremia, rather than viruria, corresponds to BKV nephropathy. The prevalence of BKV viremia in non-renal solid organ transplants has not been systematically evaluated.

METHODS

We determined prevalence of BKV viremia in kidney, combined kidney-heart, kidney-liver, kidney-pancreas, kidney-heart-liver, and heart and liver transplant recipients using BKV-PCR.

RESULTS

Seven out of 173 (4%) kidney transplant recipients had BKV viremia, with BKV>2 x 10(5) copies/mL in 6/7 and 1.9 x 10(3) in the remaining one patient. BKV viremia was not found in 24 heart transplant recipients, whereas 1/37 (2.7%) liver transplants showed low copy numbers (< or =10(3)). BKV-PCR< or =10(3) copies/mL were also found in one of each combined kidney-heart and kidney-liver transplant recipients. BKV nephropathy was proven by biopsy in 4/6 patients with high BKV viral loads. All six patients showed renal dysfunction, requiring reduction in immunosuppression and antiviral therapy. All four patients with low BKV viral loads (1.9 x 10(3) or < or =10(3)) showed stable renal function after reduction of immunosuppression or no treatment, respectively.

CONCLUSION

Higher BKV levels in plasma are associated with renal dysfunction. Kidney transplant recipients are at high risk compared with recipients of isolated heart or liver allografts, for development of BKV nephropathy.

Low incidence of BK virus nephropathy after simultaneous kidney pancreas transplantation

BACKGROUND

BK virus renal allograft nephropathy (BKVAN) in the setting of simultaneous kidney-pancreas transplantation (SKPT) has been inadequately studied and reported. We analyzed our data on the incidence of BKVAN and its outcome in SKPT recipients at University of Pittsburgh Medical Center (UPMC) and affiliated centers and report significant differences compared to previous studies.

METHODS

This study used retrospective review and case studies.

RESULTS

A review of 243 consecutive SKPT recipients from January 1, 1996 to December 31, 2004 identified seven cases (three females; ages = 23-54 yrs) of BKVAN following SKPT (incidence = 2.9%). The immunosuppressive protocols during this period were divided into: Period I (pre-August 2001) with no antibody induction and Period II (post-August 2001) with alemtuzumab or antithymocyte globulin induction with steroid avoidance. One BKVAN case was diagnosed in Period II (incidence = 1.4%). Six of seven patients were treated with intravenous cidofovir (0.20-0.50 mg/kg) every two to four weeks over one to six months. Three patients lost the renal allograft 8-22 months following diagnosis of BKVAN, whereas four patients had prolonged allograft survival. Pancreatic function was well preserved in five; one patient lost the pancreatic function due to surgical complications and one has had partial preservation.

CONCLUSIONS

There was a relatively lower incidence of BKVAN among SKPT patients at our center. Although overall graft loss rate was comparable to other series, BKVAN patients had a slightly prolonged graft life. The BKVAN incidence was further reduced in patients receiving modified immunosuppression with antibody preconditioning. The underlying reasons may include less toxic immunosuppressive protocols, earlier diagnosis and the use of antiviral therapy.

Real-time PCR in clinical microbiology: applications for routine laboratory testing

Real-time PCR has revolutionized the way clinical microbiology laboratories diagnose many human microbial infections. This testing method combines PCR chemistry with fluorescent probe detection of amplified product in the same reaction vessel. In general, both PCR and amplified product detection are completed in an hour or less, which is considerably faster than conventional PCR detection methods. Real-time PCR assays provide sensitivity and specificity equivalent to that of conventional PCR combined with Southern blot analysis, and since amplification and detection steps are performed in the same closed vessel, the risk of releasing amplified nucleic acids into the environment is negligible. The combination of excellent sensitivity and specificity, low contamination risk, and speed has made real-time PCR technology an appealing alternative to culture- or immunoassay-based testing methods for diagnosing many infectious diseases. This review focuses on the application of real-time PCR in the clinical microbiology laboratory.

Prevalence of BK virus replication among recipients of solid organ transplants

BACKGROUND

BK virus (BKV) has been implicated as a cause of nephritis and graft loss in 2%-9% of kidney transplant recipients, but the prevalence among recipients of other solid organ transplants (SOTs) has not been well established. Our objective was to determine the prevalence of BKV infection for all types of SOT recipients at our medical center.

METHODS

A total of 156 consecutive SOT recipients were studied, of whom 49 received kidney transplants, 43 received heart transplants, and 64 received liver transplants. Samples were obtained a median of 559 days (range, 1-9481 days) after transplantation. Nested polymerase chain reaction was performed for detection of BKV DNA in urine and plasma specimens.

RESULTS

BKV was found in 19% of urine specimens and 6% of plasma specimens. The prevalence of viruria after kidney, heart, and liver transplantation was 26.5%, 25.5%, and 7.8%, respectively. BKV viremia was detected in 12.2% of kidney transplant recipients and 7% of heart transplant recipients. Mean creatinine levels were higher in patients with BKV viruria or viremia (1.9 and 3.5 mg/dL, respectively) than in patients with no BKV replication (1.3 mg/dL). Independent factors related to impaired renal function were renal transplantation (odds ratio [OR], 14.4); BKV replication, including viruria or viremia (OR, 3.3); and mycophenolate use (OR, 2.6).

CONCLUSION

BKV is common in all types of SOT recipients, particularly those who have received heart or kidney transplants.

Polyoma virus nephropathy in native kidneys after lung transplantation

Polyoma virus nephropathy is recognized as an emerging clinical problem in renal transplantation; however, polyoma in native kidneys is unusual. We report a patient who developed polyoma nephropathy in his native kidneys 15 months after successful lung transplantation. His immunosuppression consisted of tacrolimus, mycophenolate mofetil, and large doses of steroids because of three rejection episodes. When the condition was recognized, cidofovir was an effective treatment (3 doses of 2-3mg/kg); however, his renal function deteriorated nonetheless. Tubulitis and interstitial cell infiltration in his native kidneys were evidence that the changes were in response to viral injury. Polyoma nephropathy of native kidneys is unusual. An earlier course of cisplatin treatment because of metastatic seminoma prior to lung transplantation may have been contributory to pre-existing renal injury. After cidofovir was begun, the polyoma viral load in serum and urine decreased substantially; however, after high-dose steroid treatment of two rejection episodes, each time a significant increase in viral load was seen. We stained biopsies of native kidneys from 30 recipients of other organs. The biopsies were done for various reasons but not because polymoma virus was suspected. We found no additional cases.

Donor origin of BK virus in renal transplantation and role of HLA C7 in susceptibility to sustained BK viremia

In a previous study, we performed serial BK virus (BKV), polymerase chain reaction (PCR) and detected active BKV infection in 70 (35.4%) of 198 renal transplant recipients. In the current study, pre-transplant donor and recipient samples were analyzed for BKV antibody titer and HLA alleles. Donor antibody titer was inversely proportional to onset of viruria, p<0.001, directly proportional to duration of viruria, p=0.014 and directly proportional to peak urine viral titer p=0.005. Recipient pairs receiving kidneys from the same donor were concordant for BKV infection, p=0.017, and had matched sequences of segments of the NCCR and VP1 genes that tended to vary among recipients of kidneys from different donors. We did not see an association of HLA A, B, or DR, HLA allele mismatches or total HLA mismatches and BK infection. However, all 11 recipients with sustained BK viremia received kidneys from donors lacking HLA C7, and 10 recipients also lacked C7. These findings derive from the largest and most comprehensive prospective study of BKV infection in renal transplant recipients performed to date. Our data support donor origin for early BKV infection in kidney transplant recipients, and suggest that a specific HLA C locus may be associated with failure to control BKV infection.

Polyomavirus-associated nephropathy in renal transplantation: interdisciplinary analyses and recommendations

Polyomavirus-associated nephropathy (PVAN) is an emerging cause of kidney transplant failure affecting 1-10% of patients. As uncertainty exists regarding risk factors, diagnosis, and intervention, an independent panel of experts reviewed the currently available evidence and prepared this report. Most cases of PVAN are elicited by BK virus (BKV) in the context of intense immunosuppression. No specific immunosuppressive drug is exclusively associated with PVAN, but most cases reported to date arise while the patient is on triple immunosuppressive combinations, often comprising tacrolimus and/or mycophenolate mofetil plus corticosteroids. Immunologic control of polyomavirus replication can be achieved by reducing, switching, and/or discontinuing components of the immunosuppressive regimen, but the individual's risk of rejection should be considered. The success rate of this intervention is increased with earlier diagnosis. Therefore, it is recommended that all renal transplant recipients should be screened for BKV replication in the urine: 1) every three months during the first two years posttransplant; 2) when allograft dysfunction is noted; and 3) when allograft biopsy is performed. A positive screening result should be confirmed in <4 weeks and assessed by quantitative assays (e.g. BKV DNA or RNA load in plasma or urine). Definitive diagnosis of PVAN requires allograft biopsy. If PVAN and concurrent acute rejection is diagnosed, antirejection treatment should be considered, coupled with subsequently reducing immunosuppression. The antiviral cidofovir is not approved for PVAN, but investigational use at low doses (0.25-0.33 mg/kg intravenously biweekly) without probenicid should be considered for refractory cases. Retransplantation after renal allograft loss to PVAN remains a treatment option for patients clearing polyomavirus replication.