Polyoma virus nephropathy in native kidneys after lung transplantation

AIDS-Associated BK Virus Nephropathy in Native Kidneys: A Case Report and Review of the Literature

BK virus (BKV) is a small DNA virus, a member of the polyomavirus family, that causes an opportunistic infection in immunocompromised patients, especially kidney transplant patients. This virus establishes a lifelong infection in most of the population, and once it reactivates in an immunocompromised state, leads to BKV nephropathy. This review seeks to assess the correlation between severe immunosuppression, evident by low CD4 cell counts in HIV-positive patients, and the reactivation of BKV, causing nephropathy. A literature review was conducted, extracting, and analyzing case reports of HIV-positive patients showing correlations between their degree of immunosuppression, as evidenced by their CD4 counts, and the degree of BKV infectivity, confirmed by kidney biopsy. A total of 12 cases of BKV nephropathy in HIV-infected patients were reviewed. A common finding was the presence of profound immunosuppression, with most patients having CD4 counts ≤50 cells/ mm3. A substantial number also had comorbid malignancies, with some undergoing chemotherapy, potentially increasing the risk of BKV reactivation. In addition to the HIV status and malignancies, other risk factors for BKV reactivation included older age, male gender, diabetes mellitus, Caucasian race, and ureteral stent placement. BKV nephropathy in HIV patients with native kidneys is closely correlated with severe immunosuppression. Although therapeutic strategies exist for post-transplant patients, aside from the treatment of HIV with highly active anti-retroviral therapy (HAART), which potentially helps with clearing BKV by increasing CD4 count, there is no definitive treatment for a native kidney BKV nephropathy in patients with AIDS. The complexity of the cases and severity of comorbidities indicate the need for further research to develop therapeutic strategies tailored to this population.

BK DNAemia and native kidney polyomavirus nephropathy following lung transplantation

BK virus DNAemia (BKPyV) and nephropathy are common after kidney transplant; however, there are limited data on BK infections in nonrenal solid organ transplant recipients. We examined the frequency, clinical and pathologic features, and kidney and lung outcomes of BKPyV and BK virus native kidney nephropathy (BKVN) in lung transplant recipients at our center. Among 878 recipients transplanted from 2003 to 2019, 56 (6%) developed BKPyV at a median of 30.1 months after transplant (range, 0.6-213) and 11 (1.3%) developed BKVN at a median of 46 months after transplant (range, 9-213). The incidence of end-stage kidney disease was significantly higher in patients with peak viral load ≥10 000 copies/mL (39% vs 8%, P < .001). All cases of BKVN were in patients with peak viral load of ≥10 000 copies/mL, and 55% of these patients developed end-stage kidney disease. Despite the reduction of immunosuppression to treat BKVN, only 1 patient developed acute rejection, and lung function was stable >1 year. BKPyV and nephropathy are more common after lung transplantation than previously reported. Routine screening for BKPyV should be considered in all lung transplant recipients.

Native BK virus nephropathy in lung transplant: a case report and literature review

Classically described in renal allografts, BK virus nephropathy is increasingly recognized in native kidneys of other non-renal solid organ transplants. We discuss a 68-year-old woman with a history of bilateral lung transplant referred for worsening renal function, confirmed to have BK virus nephropathy by biopsy with a serum BK virus polymerase chain reaction of over 59 million copies/mL. She was managed with a reduction in immunosuppression and intravenous cidofovir with no improvement in her clinical parameters. The seven prior reported cases of polyoma virus nephropathy in lung transplant recipients are reviewed, and the challenges of screening and management are discussed.

Antivirals against human polyomaviruses: Leaving no stone unturned

Human polyomaviruses (HPyVs) encompass more than 10 species infecting 30%-90% of the human population without significant illness. Proven HPyV diseases with documented histopathology affect primarily immunocompromised hosts with manifestations in brain, skin and renourinary tract such as polyomavirus-associated nephropathy (PyVAN), polyomavirus-associated haemorrhagic cystitis (PyVHC), polyomavirus-associated urothelial cancer (PyVUC), progressive multifocal leukoencephalopathy (PML), Merkel cell carcinoma (MCC), Trichodysplasia spinulosa (TS) and pruritic hyperproliferative keratinopathy. Although virus-specific immune control is the eventual goal of therapy and lasting cure, antiviral treatments are urgently needed in order to reduce or prevent HPyV diseases and thereby bridging the time needed to establish virus-specific immunity. However, the small dsDNA genome of only 5 kb of the non-enveloped HPyVs only encodes 5-7 viral proteins. Thus, HPyV replication relies heavily on host cell factors, thereby limiting both, number and type of specific virus-encoded antiviral targets. Lack of cost-effective high-throughput screening systems and relevant small animal models complicates the preclinical development. Current clinical studies are limited by small case numbers, poorly efficacious compounds and absence of proper randomized trial design. Here, we review preclinical and clinical studies that evaluated small molecules with presumed antiviral activity against HPyVs and provide an outlook regarding potential new antiviral strategies.

BK virus nephropathy in non-renal solid organ transplant recipients: Are we looking hard enough?

We retrospectively examined the clinical characteristics, pathological features, and outcomes of BK viremia and nephropathy in a population of non-renal solid organ transplant patients (NRSOT) referred for outpatient nephrology consultation over a period of 5 years. In the entire cohort of liver, heart, and lung transplant recipients referred to this clinic, 14% percent were found to have BK viremia with a median peak serum BK viral load of 35 500 copies/ml (range 250 to 21 100 000 copies/ml). BK viremia resolved in six of the seventeen patients (35%). Four out of five patients biopsied showed BK virus (BKV) nephropathy. Eleven out of seventeen patients with BK viremia developed advanced (stage 4 or 5) chronic kidney disease. Four patients developed rejection of their solid organ transplant within the first year post detection of BK viremia after immunosuppression reduction. We conclude that a multi-center study is required to evaluate whether implementation of a systematic BK screening program would be effective in early detection and management of this problem in the NRSOT population.

Intragraft gene expression in native kidney BK virus nephropathy versus T cell-mediated rejection: Prospects for molecular diagnosis and risk prediction

Novel tools are needed to improve diagnostic accuracy and risk prediction in BK virus nephropathy (BKVN). We assessed the utility of intragraft gene expression testing for these purposes. Eight hundred genes were measured in 110 archival samples, including a discovery cohort of native kidney BKVN (n = 5) vs pure T cell-mediated rejection (TCMR; n = 10). Five polyomavirus genes and seven immune-related genes (five associated with BKVN and two associated with TCMR) were significantly differentially expressed between these entities (FDR < 0.05). These three sets of genes were further evaluated in samples representing a spectrum of BK infection (n = 25), followed by a multicenter validation cohort of allograft BKVN (n = 60) vs TCMR (n = 10). Polyomavirus 5-gene set expression reliably distinguished BKVN from TCMR (validation cohort AUC = 0.992), but the immune gene sets demonstrated suboptimal diagnostic performance (AUC ≤ 0.720). Within the validation cohort, no significant differences in index biopsy gene expression were identified between BKVN patients demonstrating resolution (n = 35), persistent infection (n = 14) or de novo rejection (n = 11) 6 months following a standardized reduction in immunosuppression. These results suggest that, while intragraft polyomavirus gene expression may be useful as an ancillary diagnostic for BKVN, assessment for concurrent TCMR and prediction of clinical outcome may not be feasible with current molecular tools.

BK virus-associated nephropathy in a lung transplant patient: case report and literature review

BACKGROUND

BK virus-associated nephropathy (BKVAN) is a relatively common cause of renal dysfunction in the first six months after renal transplantation. It arises from reactivation of the latent and usually harmless BK virus (BK virus) due to immunosuppression and other factors including some that are unique to renal transplantation such as allograft injury. BKVAN is much rarer in non-renal solid organ transplantation, where data regarding diagnosis and management are extremely limited.

CASE PRESENTATION

We report a case of a 58-year-old man found to have worsening renal dysfunction nine months after bilateral sequential lung transplantation for chronic obstructive pulmonary disease (COPD). He had required methylprednisolone for acute allograft rejection but achieved good graft function. Urine microscopy and culture and renal ultrasound were normal. BK virus PCR was positive at high levels in urine and blood. Renal biopsy subsequently confirmed BKVAN. The patient progressed to end-stage renal failure requiring haemodialysis despite reduction in immunosuppression, including switching mycophenolate for everolimus, and the administration of intravenous immunoglobulin (IVIG).

CONCLUSIONS

This very rare case highlights the challenges presented by BK virus in the non-renal solid organ transplant population. Diagnosis can be difficult, especially given the heterogeneity with which BKV disease has been reported to present in such patients, and the optimal approach to management is unknown. Balancing reduction in immunosuppression against prevention of allograft rejection is delicate. Improved therapeutic options are clearly required.

Pathogenicity of BK virus on the urinary system

Introduction

The polyomaviruses are omnipresent in nature. The major sites of BK virus appearance are the kidney tubular epithelial cells and urinary bladder surface transitional cells.

Material and methods

A literature search according to PRISMA guidelines within the Medline database was conducted in July 2019 for articles presenting data about BK virus in urologic aspect without setting time limits, using the terms ‘BK virus’ in conjunction with transplantation, nephropathy, stenosis, cancer, bladder, prostate, kidney.

Results

The BK virus usually stays latent, however, its replication may become active in various clinical situations of impaired immunocompetence such as solid organ transplantation, bone marrow transplantation, AIDS, pregnancy, multiple sclerosis, administration of chemotherapy or biologic therapy. BK virus is associated with two main complications after transplantation: polyomavirus-associated nephropathy in kidney transplant patients and polyomavirus-associated hemorrhagic cystitis in allogeneic hematopoietic stem cell transplant patients.

Conclusions

The aim of this article was to present available data on urologic aspects of BK virus infection, its detection methods and available treatment.

BK virus histopathologic disease severity does not predict allograft outcome in renal transplant recipients

AIMS

BK polyomavirus nephropathy (BKPyVN) is an important cause of allograft failure after renal transplantation. Despite early screening for the virus, allograft loss from BKPyVN is still experienced in up to 14% of all renal transplant recipients. The aim of this study was to investigate the association between BKPyVN histopathologic disease severity and allograft outcome at our center.

METHODS

Kidney transplant recipients who had undergone transplantation between 2002 and 2014 with biopsy proven BKPyVN were eligible for this retrospective study. Each biopsy was re-evaluated by a single pathologist blinded to the clinical data and scored according to the Banff criteria for rejection and BKPyVN. Serum creatinine and BK viral load at the time of biopsy diagnosis as well as allograft outcomes to include allograft survival and serum BK viremia resolution were collected for each recipient to determine if BK virus histopathologic disease severity could predict allograft outcome.

RESULTS

Twenty cases of BKPyVN were identified from 1031 total renal transplants performed. There was no statistical association between allograft loss and BKPyVN histopathology (p = 0.49). There was also no statistical association between BKPyVN histopathology and BK viral load at the time of biopsy diagnosis (p = 0.38) or serum BK viremia resolution (p = 0.16).

CONCLUSIONS

BKPyVN histopathology does not appear to be useful in predicting renal allograft outcome in those recipients diagnosed with BKPyVN which is in contrast to some previously published data.

Native kidney BK virus nephropathy, a systematic review

BACKGROUND

There is a growing base of literature describing BK nephropathy (BKVN) in patients outside of the setting of kidney transplant. Previous systematic reviews of the literature have been limited by methodology or by the scope of patients included.

STUDY DESIGN AND METHODS

Systematic Review (Prospero # CRD42018088524).

SETTING & POPULATION

Patients without kidney transplant who had biopsy-proven BKVN.

SELECTION CRITERIA FOR STUDIES

Full-text articles that describe native BKVN patient cases.

ANALYTICAL APPROACH

Descriptive synthesis.

RESULTS

The search identified 630 unique articles of which 51 were included in the final review. Sixty-five cases (including two new cases presented in this review) were identified, all but one occurred in the setting of known immunosuppression.

LIMITATIONS

The primary limitation was the exclusion of studies that did not fulfill the stringent review criteria. We excluded reports with only a clinical diagnosis of BKVN, such as those with viruria and/or viremia without biopsy.

CONCLUSIONS

As of May 2018, there are 65 reported cases of BKVN in native kidneys. This represents the most comprehensive description of biopsy-proven BKVN in native kidneys to date. Evaluation for BK nephropathy should be considered in immunocompromised patients who exhibit unexplained renal failure.

BK virus-associated viruria and viremia in a patient with lymphangioleiomyomatosis after lung re-transplantation: A case report and review of the literature on BK virus infection post-lung transplantation

The BK virus (BKV) is a member of the polyomaviridae family of DNA viruses. BKV reactivates under a highly immunosuppressed state and causes renal dysfunction. In renal transplant patients, BKV infection leads to tubular impairment and loss of transplanted kidney grafts. However, few studies have reported on the relationship between BKV and lung transplantation. Adjustment of the dosage of immunosuppressants is needed in some cases, but the treatment method has not been established. Here, we report a case of BKV-associated viruria and viremia in a patient with lymphangioleiomyomatosis (LAM) after lung re-transplantation. A 44-year-old female refractory LAM patient who had undergone lung re-transplantation 3 months earlier was diagnosed with BKV-associated viruria and viremia. Urine cytology indicated decoy cells and the urine and serum polymerase chain reaction test was positive for BKV. As scheduled after re-transplantation surgery, immunosuppressive drugs were progressively reduced. This patient was considered to have experienced spontaneous BKV-associated viremia and viruria. Review of the literature suggested that 17%-42% of BKV-associated viruria cases have been reported after lung transplantation, but cases of BKV-associated nephropathy are rarely reported. Based on the present case, doctors involved in lung transplantation should monitor patients for BKV infection. Decoy cell monitoring by urine cytology is a useful screening method in the follow-up observation after lung transplantation. Early-stage interventions may prevent BKV-associated nephropathy even in patients who have developed BKV viremia, and sirolimus can be administered to patients with histories of BKV infection if they are carefully monitored.

BK Virus: A Cause for Concern in Thoracic Transplantation?

Human BK polyomavirus (BKV) infection is poorly documented in heart and lung transplant patients. BK viruria and viremia have been estimated to affect 19% and 5% of heart transplant recipients, respectively. Data are limited, especially for lung transplantation, but the proportion of patients progressing from BK viruria to viremia or BKV-related nephropathy (BKVN) appears lower than in kidney transplantation. Nevertheless, a number of cases of BKVN have been reported in heart and lung transplant patients, typically with late diagnosis and generally poor outcomes. Risk factors for BKV infection or BKVN in this setting are unclear but may include cytomegalovirus infection and anti-rejection treatment. The relative infrequency of BKVN or other BK-related complications means that routine BKV surveillance in thoracic transplantation is not warranted, but a diagnostic workup for BKV infection may be justified for progressive renal dysfunction with no readily-identifiable cause; after anti-rejection therapy; and for renal dysfunction in patients with cytomegalovirus infection or hypogammaglobulinemia. Treatment strategies in heart or lung transplant recipients rely on protocols developed in kidney transplantation, with reductions in immunosuppression tailored to match the higher risk status of thoracic transplant patients.

Respiratory Viruses and Other Relevant Viral Infections in the Lung Transplant Recipient

As advances occur in surgical technique, postoperative care, and immunosuppressive therapy, the rate of mortality in the early postoperative period following lung transplantation continues to decline. With the improvements in immediate and early posttransplant mortality, infections and their sequel as well as rejection and chronic allograft dysfunction are increasingly a major cause of posttransplant mortality. This chapter will focus on infections by respiratory viruses and other viral infections relevant to lung transplantation, including data regarding the link between viral infections and allograft dysfunction.

Polyomavirus Nephropathy in Native Kidneys of an Immunocompetent Individual

BACKGROUND Polyomavirus nephropathy has emerged as an important cause of graft loss in kidney transplant recipients. Polyomavirus rarely affects the native kidneys of an immunocompetent individual. Until now, polyomavirus nephropathy in native kidneys of an immunocompetent individual has not been reported, as far as we know. CASE REPORT A 34-year-old man was transferred from a local clinic to be evaluated for the cause of azotemia. Serum creatinine was 2.85 mg/dL. We performed renal biopsy to identify the cause of azotemia. The result of kidney biopsy was consisted to polyomavirus nephropathy. CONCLUSIONS We report the first case of polyomavirus nephropathy in native kidneys of an immunocompetent individual.

BK nephropathy in the native kidneys of patients with organ transplants: Clinical spectrum of BK infection

Nephropathy secondary to BK virus, a member of the Papoviridae family of viruses, has been recognized for some time as an important cause of allograft dysfunction in renal transplant recipients. In recent times, BK nephropathy (BKN) of the native kidneys has being increasingly recognized as a cause of chronic kidney disease in patients with solid organ transplants, bone marrow transplants and in patients with other clinical entities associated with immunosuppression. In such patients renal dysfunction is often attributed to other factors including nephrotoxicity of medications used to prevent rejection of the transplanted organs. Renal biopsy is required for the diagnosis of BKN. Quantitation of the BK viral load in blood and urine are surrogate diagnostic methods. The treatment of BKN is based on reduction of the immunosuppressive medications. Several compounds have shown antiviral activity, but have not consistently shown to have beneficial effects in BKN. In addition to BKN, BK viral infection can cause severe urinary bladder cystitis, ureteritis and urinary tract obstruction as well as manifestations in other organ systems including the central nervous system, the respiratory system, the gastrointestinal system and the hematopoietic system. BK viral infection has also been implicated in tumorigenesis. The spectrum of clinical manifestations from BK infection and infection from other members of the Papoviridae family is widening. Prevention and treatment of BK infection and infections from other Papovaviruses are subjects of intense research.

Viral Origin, Clinical Course, and Renal Outcomes in Patients With BK Virus Infection After Living-Donor Renal Transplantation

BACKGROUND

BK virus (BKV) nephropathy remains the main cause of renal graft loss after living-donor renal transplantation. The aim of the study was to investigate the source and factors influencing the course of BKV infection.

METHODS

We investigated 214 living donor-recipient pairs. Urine and blood of donors and recipients were tested by qPCR for the presence of BKV DNA before and after transplantation; genotyping of BKV subtypes was performed.

RESULTS

Eighty-five recipients (40%) had posttransplant BK viruria including 61 with additional viremia and 22 with nephropathy. Pretransplant urinary BKV shedding of donor or recipient was a significant risk factor for posttransplant viruria and viremia (OR, 4.52; CI, 2.33-8.77; P < 0.0001) and nephropathy (OR, 3.03; CI, 1.16-7.9; P = 0.02). In the BKV nephropathy group, urine and blood became BKV positive earlier than in the group with viruria and viremia. Renal function was worse in BKV-nephropathy compared with BKV-negative patients beginning at transplantation. Comparing BKV subtypes of donor and recipient before with the subtype of the infected recipient after transplantation, donor-derived transmission was identified in 24 of 28 corresponding pairs. BKV subtype IV had a higher prevalence in recipients with BKV nephropathy than in those with viruria and viremia (P = 0.045).

CONCLUSIONS

Pretransplant urinary BKV shedding of donor and recipient is a risk for posttransplant infection. Donor-derived BKV transmission is an important mode of infection. BKV subtype IV may be one of the viral determinants. Early BKV positivity of urine and blood indicates later BKV nephropathy. Decreased renal function may favor BKV infection.

BK polyoma virus infection and renal disease in non-renal solid organ transplantation

BK virus (BKV) is a non-enveloped DNA virus of the polyomaviridae family that causes an interstitial nephritis in immunosuppressed patients. BKV nephropathy is now a leading cause of chronic kidney disease and early allograft failure following kidney transplantation. It is also known to cause renal disease with a progressive decline in kidney function in non-renal solid organ transplant (NRSOT) recipients, although the disease may not be recognized nor its impact appreciated in this patient population. In this report, we review the existing literature to highlight our current understanding of its incidence in NRSOT populations, the approaches to diagnosis and the potential treatment options.

The Impact of Infection on Chronic Allograft Dysfunction and Allograft Survival After Solid Organ Transplantation

Infectious diseases after solid organ transplantation (SOT) are a significant cause of morbidity and reduced allograft and patient survival; however, the influence of infection on the development of chronic allograft dysfunction has not been completely delineated. Some viral infections appear to affect allograft function by both inducing direct tissue damage and immunologically related injury, including acute rejection. In particular, this has been observed for cytomegalovirus (CMV) infection in all SOT recipients and for BK virus infection in kidney transplant recipients, for community-acquired respiratory viruses in lung transplant recipients, and for hepatitis C virus in liver transplant recipients. The impact of bacterial and fungal infections is less clear, but bacterial urinary tract infections and respiratory tract colonization by Pseudomonas aeruginosa and Aspergillus spp appear to be correlated with higher rates of chronic allograft dysfunction in kidney and lung transplant recipients, respectively. Evidence supports the beneficial effects of the use of antiviral prophylaxis for CMV in improving allograft function and survival in SOT recipients. Nevertheless, there is still a need for prospective interventional trials assessing the potential effects of preventive and therapeutic strategies against bacterial and fungal infection for reducing or delaying the development of chronic allograft dysfunction.

European perspective on human polyomavirus infection, replication and disease in solid organ transplantation

Human polyomaviruses (HPyVs) are a growing challenge in immunocompromised patients in view of the increasing number of now 12 HPyV species and their diverse disease potential. Currently, histological evidence of disease is available for BKPyV causing nephropathy and haemorrhagic cystitis, JCPyV causing progressive multifocal leukoencephalopathy and occasionally nephropathy, MCPyV causing Merkel cell carcinoma and TSPyV causing trichodysplasia spinulosa, the last two being proliferative skin diseases. Here, the current role of HPyV in solid organ transplantation (SOT) was reviewed and recommendations regarding screening, monitoring and intervention were made. Pre-transplant screening of SOT donor or recipient for serostatus or active replication is currently not recommended for any HPyV. Post-transplant, however, regular clinical search for skin lesions, including those associated with MCPyV or TSPyV, is recommended in all SOT recipients. Also, regular screening for BKPyV replication (e.g. by plasma viral load) is recommended in kidney transplant recipients. For SOT patients with probable or proven HPyV disease, reducing immunosuppression should be considered to permit regaining of immune control. Antivirals would be desirable for treating proven HPyV disease, but are solely considered as adjunct local treatment of trichodysplasia spinulosa, whereas surgical resection and chemotherapy are key in Merkel cell carcinoma. Overall, the quality of the clinical evidence and the strength of most recommendations are presently limited, but are expected to improve in the coming years.

Review article: BK virus in systemic lupus erythematosus

BK virus (BKV) is a human polyomavirus with a seroprevalence of 60-80 % in the general population. In renal transplant patients, it is known to cause renal failure, ureteric stenosis and hemorrhagic cystitis. In bone marrow transplant patients, it is evident that BKV can also cause hemorrhagic cystitis along with BK virus nephropathy (BKVN) in the native kidneys, with subsequent renal failure. However, little is known about BVKN in non-transplanted immune-compromised patients, such as systemic lupus erythematosus (SLE) who may have underlying nephritis and have a compromised immune system due to therapy and/or systemic illness. Thus, this article will focus on the clinical aspects of BKV and its association in patients with SLE.

Toward standardization of BK virus monitoring: evaluation of the BK virus R-gene kit for quantification of BK viral load in urine, whole-blood, and plasma specimens

Screening of BK virus (BKV) replication is recommended to identify patients at increased risk of BKV-associated diseases. However, the heterogeneity of molecular techniques hinders the establishment of universal guidelines for BKV monitoring. Here we aimed to compare the performance of the CE-marked BK virus R-gene kit (R-gene) to the performance of our in-house assay for quantification of BKV DNA loads (BKVL). A 12-specimen panel from the Quality Control for Molecular Diagnostics (QCMD) organization, 163 urine samples, and 88 paired specimens of plasma and whole blood (WB) from transplant recipients were tested. Both the R-gene and in-house assays showed a good correlation within the QCMD panel (r = 0.995 and r = 0.989, respectively). BKVL were highly correlated between assays, although positive biases were observed with the in-house assay in analysis of urine (0.72 ± 0.83 log10 copies/ml), plasma (1.17 ± 0.63 log10 copies/ml), and WB (1.28 ± 0.37 log10 copies/ml). Recalibration with a common calibrator significantly reduced the bias in comparisons between assays. In contrast, BKVL was underestimated with the in-house PCR in eight samples containing BKV genotype II, presenting point mutations at primer-annealing sites. Using the R-gene assay, plasma and WB specimens were found to be equally suitable for quantification of BKVL, as indicated by the high correlation coefficient (r = 0.965, P < 0.0001). In conclusion, the R-gene assay demonstrated reliable performance and higher accuracy than the in-house assay for quantification of BKVL in urine and blood specimens. Screening of BKV replication by a well-validated commercial kit may enable clinical laboratories to assess viral loads with greater reproducibility and precision.

BK polyoma virus nephropathy in the native kidney

BACKGROUND

While BK polyoma virus nephropathy (PVN) is a well-recognized cause of renal allograft dysfunction, PVN of native kidneys is likely under-recognized.

METHODS

We present the pathologic features, risk factors and outcomes of eight cases of PVN in native kidneys.

RESULTS

The cohort included eight males aged 16-73 years (mean 47.4) with an immunocompromised state (mean duration 3.15 years) attributable to: hematologic malignancies (n = 6), for which three had undergone bone marrow transplant; lung transplant (n = 1) and combined tuberculosis and diabetes (n = 1). Seven patients were receiving specific immunosuppressive therapies. Patients were biopsied for acute kidney injury (AKI) with rise in mean creatinine levels from baseline 1.6 to 2.8 mg/dL. Pathology showed BK PVN with characteristic intranuclear inclusions staining positive for SV40 T antigen and negative for JC virus (JCV), with positive serum and/or urine PCR for BK virus. One patient had focal medullary JCV co-infection. Two patients also had renal infiltration by chronic lymphocytic leukemia (CLL). Six patients received specific therapy directed to PVN (cidofovir or leflunomide). Follow-up ranged from 2 to 20 (mean 10) months. Despite marked decrease in serum BK viral copy numbers, creatinine continued to rise in six cases (mean 3.7 mg/dL in four, requiring dialysis in two) and three patients died of malignancy, opportunistic infection or renal failure. Advanced histologic stage of PVN, ineffective antiviral therapy, co-morbidities and persistent immunocompromised state likely contributed to the poor outcomes.

CONCLUSION

A high level of suspicion in immunocompromised patients is needed to diagnose PVN in an early stage that may respond more favorably to antiviral therapy.

A child with BK virus infection: inadequacy of current therapeutic strategies

In this report, we describe the development of BKVN in the native kidneys of a child with a cardiac transplant. Elevated BK viral DNA load by PCR necessitated a prolonged course of treatment with escalating doses of cidofovir. Despite a reduction in plasma BK viral load, the infection evolved into an invasive CNS disease, resulting in rhomboencephalitis. This case highlights the need for awareness of the possibility of developing multiorgan complications from BKV infection. The current treatment options for BKV tissue invasive disease are inadequate and need to be improved.

Polyomavirus JC urinary shedding in kidney and liver transplant recipients associated with reduced creatinine clearance

BACKGROUND

Polyomavirus reactivation can cause significant morbidity in solid organ transplant recipients, particularly BK virus (BKV) in kidney transplant patients. Less is known about dynamics of John Cunningham virus (JCV) in nonkidney organ transplant patients.

METHODS

We examined the frequency of urinary shedding of polyomaviruses BKV and JCV and their relationship to creatinine clearance (CrCl) in a longitudinal study of 41 kidney and 33 liver transplant recipients.

RESULTS

Any polyomavirus urinary shedding was more frequent in liver than kidney recipients (64% vs 39%; P= .03). JCV was excreted more frequently by liver than kidney recipients (71% vs 38%), whereas BKV was shed more often by kidney than liver patients (69% vs 52%). Mean JCV loads were significantly higher than those of BKV in both patient groups (P< .0001). Lower mean CrCl values were significantly associated with JCV shedding in both kidney and liver recipients (P< .001).

CONCLUSIONS

These findings suggest that BKV and JCV display different patterns of reactivation and shedding in kidney and liver transplant patients and that JCV may have a role in renal dysfunction in some solid organ transplant recipients.

Development of a real-time quantitative PCR assay for detection of a stable genomic region of BK virus

BACKGROUND

BK virus infections can have clinically significant consequences in immunocompromised individuals. Detection and monitoring of active BK virus infections in certain situations is recommended and therefore PCR assays for detection of BK virus have been developed. The performance of current BK PCR detection assays is limited by the existence of viral polymorphisms, unknown at the time of assay development, resulting in inconsistent detection of BK virus. The objective of this study was to identify a stable region of the BK viral genome for detection by PCR that would be minimally affected by polymorphisms as more sequence data for BK virus becomes available.

RESULTS

Employing a combination of techniques, including amino acid and DNA sequence alignment and interspecies analysis, a conserved, stable PCR target region of the BK viral genomic region was identified within the VP2 gene. A real-time quantitative PCR assay was then developed that is specific for BK virus, has an analytical sensitivity of 15 copies/reaction (450 copies/ml) and is highly reproducible (CV ≤ 5.0%).

CONCLUSION

Identifying stable PCR target regions when limited DNA sequence data is available may be possible by combining multiple analysis techniques to elucidate potential functional constraints on genomic regions. Applying this approach to the development of a real-time quantitative PCR assay for BK virus resulted in an accurate method with potential clinical applications and advantages over existing BK assays.

Renal failure five years after lung transplantation due to polyomavirus BK-associated nephropathy

Polyomavirus-associated nephropathy (PyVAN) is rare in nonrenal solid organ transplantation and only limited information is available from single cases. We describe a 67-year-old female presenting with hypertension and progressive kidney failure due to PyVAN 60 months after lung transplantation. Plasma BK virus (BKV) loads were 4.85 log¹⁰ copies/mL at diagnosis and cleared slowly over 14 months after switching from tacrolimus, mycophenolate and prednisone to low-dose tacrolimus, sirolimus and leflunomide, the latter being discontinued for anemia and diarrhea. BKV- and JC virus-specific immunoglobulins were detectable prior to transplantation. Only BKV-specific IgG and IgM increased during follow-up. BKV-specific T cells were detectable in blood following in vitro expansion, but cleared with reincreased sirolimus, yet BKV viremia remained undetectable. We identified eight other cases of PyVAN in nonrenal solid organ transplantation including lung (n = 1), heart (n = 6) and pancreas (n = 1). Overall, diagnosis was later than commonly seen in kidney transplants (median 18 months, interquartile range 10-29). Seven patients were male, five received triple immunosuppression consisting of tacrolimus, mycophenolate, prednisone. Immunosuppression was reduced in four cases and cidofovir and/or leflunomide administered in five and two cases, respectively. Renal function deteriorated in five requiring hemodialysis in four. We discuss mTOR inhibitors versus cidofovir and leflunomide as potential PyVAN rescue therapy.

Biopsy-diagnosed renal disease in patients after transplantation of other organs and tissues

Renal function deteriorates in about half of patients undergoing other transplants. We report the results of 105 renal biopsies from 101 nonrenal transplant recipients (bone marrow 14, liver 41, lung 30, heart 20). Biopsy indications were protracted acute renal failure (9%), creatinine increases (83%), heavy proteinuria (22%), or renal insufficiency before re-transplantation (9%). Histological findings other than nonspecific chronic changes, hypertension-related damage, and signs of chronic CNI toxicity included primary glomerular disease (17%), mostly after liver transplantation (21%) or after bone marrow transplantation (29%), and thrombotic microangiopathy (TMA) namely (10%). TMA had the most serious impact on the clinical course. Besides severe hypertension, one TMA patient died of cerebral hemorrhage, 5 had hemolytic-uremic syndrome, and 6 rapidly developed end-stage renal failure. TMA patients had the shortest kidney survival post-biopsy and, together with patients with acute tubular injury, the shortest kidney and patient survival since transplantation. Nine TMA patients had received CNI, 3 of them concomitantly received an mTOR-inhibitor. CNI toxicity is implicated in most patients with renal failure after transplant of other organs and may play a role in the development of TMA, the most serious complication. However, decreased renal function should not be routinely ascribed to CNI.

Native BK viral nephropathy in a pediatric heart transplant recipient

BK viral nephropathy is a well-documented clinical entity in kidney transplant recipients and a significant cause of morbidity and allograft loss in affected patients. BK viral nephropathy in native kidneys of non-kidney transplant recipients is relatively uncommon, but has been reported in adult patients. We report the occurrence of BK viral nephropathy in a pediatric heart transplant recipient. A 10-yr-old boy with past history of Ewing's sarcoma underwent heart transplantation for dilated cardiomyopathy induced by previous chemotherapy with doxorubicin. Post-transplant course was complicated by grade 3A rejection and CMV colitis. He was diagnosed with native BK viral nephropathy approximately 18 months post-transplant due to mild, but persistent, elevation in serum creatinine associated with proteinuria. BK viral nephropathy affects non-kidney transplant recipients, and a high index of suspicion is necessary for early diagnosis and management of this condition.

BK virus nephropathy in the native kidneys of a pediatric heart transplant recipient

BK virus is a human polyoma virus that may cause nephropathy in immunosuppressed patients. It is a well-recognized cause of renal allograft dysfunction and allograft loss in renal transplant recipients, but it is an infrequent cause of nephropathy outside this setting. There are a few case reports of BK virus nephropathy in the native kidneys of immunosuppressed adult patients with non-renal transplants, but so far it has not been reported in pediatric non-renal solid organ transplant recipients. We report a case of a seven-yr-old heart transplant patient who was diagnosed with BK virus nephropathy, eight months after his second heart transplant. Despite intervention, his renal dysfunction progressed to renal failure. He is currently receiving maintenance hemodialysis and awaiting renal transplantation. It is important to recognize BK virus infection as a possible cause of renal dysfunction in immunosuppressed children who are non-renal transplant recipients.

Prevalence of polyomavirus viruria (JC virus/BK virus) in children following liver transplantation

BKV infection is a potential cause of renal dysfunction in non-renal organ transplant recipients. JCV is the causative agent of PML. Furthermore, polyomaviruses are tumor inducing viruses and molecular data suggest an association with malignancies among solid organ transplant patients. So far, there are no studies analyzing polyomavirus viruria following Ltx in children. We performed a prospective prevalence study at a mean of 2187 (range 20-5671) days after transplantation in 100 consecutive children admitted for the routine follow-up examination post-Ltx. The urine was screened for BKV and JCV DNA by using PCR in each case. A plasma analysis by PCR was also done if more than 100,000 DNA copies/mL urine were detected. BKV or JCV viruria was found in 19% (n = 19) of our patients. All patients were free of clinical signs of viral infection, PML, or nephropathy. GFR was normal in 97% of patients and we found no statistical difference of kidney function between patients with and without BKV/JCV viruria. The extent of immunosuppressive therapy had no influence on the polyomavirus viruria. Overall, we found a higher prevalence of polyomavirus viruria in our pediatric liver transplant recipients than reported in adult patients.

BK virus in liver transplant recipients: a prospective study

BACKGROUND

BK virus (BKV) is a polyomavirus that is associated with nephropathy and graft loss among kidney transplant recipients. The role of BK virus in nonrenal solid organ transplant recipients has not been clearly established; only anecdotal case reports have been published.

METHODS

From August 2005 to September 2007, all liver transplant (OLT) recipients who gave their consent were enrolled in this prospective longitudinal study. BK viral load was measured using real-time quantitative polymerase chain reaction assays of urine and plasma, using samples collected at week 1 and months 1, 3, 6, 9, 12, 15, 18, 21, and 24 posttransplantation. We also collected demographic and clinical data, including serum creatinine and immunosuppressive therapy.

RESULTS

The mean age of the 62 patients was 51.4 years including 14 (22.5%) women. Hepatitis C infection was present in 24 patients (38.7%). BK viruria was detected in 14.5% of 290 samples, corresponding to 13 patients (21%). BK viremia was detected in 5.1% of 317 samples, corresponding to 11 patients (18%). Almost all cases of BK viremia (91%) occurred in the first 3 months after OLT. BKV viremia was more common among patients experiencing a rejection episode (10.6 vs 40%, P = .01). We did not observe a relationship between single episodes of BKV replication and renal function: median plasma creatinine 1.1 mg/dL in patients without versus 1.2 mg/dL with BKV viremia. The three patients with persistent viremia displayed renal insufficiency; one of them died due to multiorgan failure of unknown origin.

CONCLUSIONS

BKV is frequently detected in OLT recipients (viruria 21% and viremia 18%) early after transplantation. It is more common among patients with rejection episodes. Persistent BKV viremia may be related to renal dysfunction in OLT patients.

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.

Decline in native kidney function in liver transplant recipients is not associated with BK virus infection

BK virus (BKV) infection is an established cause of allograft dysfunction in renal transplant recipients. The relationship between BKV infection and chronic kidney disease (CKD) post-orthotopic liver transplantation (OLT) is not well understood. This study aimed to determine the prevalence of BKV infection, its relationship to CKD and renal function loss over time in patients receiving OLT. Prevalence of BK viruria and viremia were studied in 41 post-OLT patients after a mean 6.5 +/- 4.7 years posttransplantation. Renal function was assessed using estimated glomerular filtration rate (eGFR) calculated from the yearly serum creatinine levels using the Modification of Diet in Renal Disease (MDRD) formula. Polymerase chain reaction (PCR) was performed for detection of BKV DNA in urine and plasma. BK viruria was present in 24.2% of patients, but none of these OLT recipients had detectable BK viremia. Decoy cells in the urine were found in 9.7% patients, although none of these patients had BK viruria. CKD, defined as eGFR <60 mL/minute/1.73 m(2), was found in 83% of OLT recipients. The yearly decline in eGFR was -6.9 +/- 17 and -9.2 +/- 18 mL/minute/year in BK viruria-positive and BK viruria-negative patients, respectively (P = 0.39). There was no relationship between the presence or absence of BK viruria and either current eGFR, yearly decline in eGFR, number and type of immunosuppressive agents, or etiology of liver failure. In OLT recipients, BK viruria is not associated with BK viremia or native kidney dysfunction. It appears that the most probable pathway for the development of BKV nephropathy requires a second hit, such as kidney inflammation, kidney ischemia, or donor-recipient human leukocyte antigen mismatch.

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-associated hemorrhagic cystitis in a pediatric lung transplant recipient

BKV was first postulated to be a potential pathogen in 1971 when it was isolated in the urine of a renal transplant recipient. The pathology of BKV is generally confined to the urinary tract. In renal transplant recipients, BKV has been associated with hemorrhagic cystitis, urethral stenosis, and interstitial nephritis. Reports of BKV infection in lung transplant recipients are limited to a few case reports in adult patients. A recent report revealed that up to 32% of adult lung transplant recipients may shed BKV in their urine without symptoms or renal dysfunction. To our knowledge, there are no published reports of pediatric lung transplant recipients with BKV-associated hematuria. We hereby report a case of BKV-induced hemorrhagic cystitis in a pediatric lung transplant recipient.

Spectrum of renal pathology in hematopoietic cell transplantation: a series of 20 patients and review of the literature

BACKGROUND AND OBJECTIVES

Hematopoietic cell transplantation is a common treatment option for a variety of hematopoietic malignancies. As a result of the use of total body irradiation and/or chemotherapeutic agents, renal dysfunction often ensues. Many pharmacologic agents, such as cyclosporine and high-intensity conditioning regimens, have been linked with thrombotic microangiopathy. In addition, an association between membranous nephropathy and graft-versus-host disease has been reported in this clinical setting.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

A study of autologous and allogeneic hematopoietic cell transplantation patients with renal dysfunction was conducted to document the spectrum of renal manifestations. The pathology files at the University of Washington and University of Chicago Medical Centers were reviewed, and 20 patients with a kidney biopsy after hematopoietic cell transplantation were identified. The histologic findings were correlated with relevant clinical information.

RESULTS

A wide spectrum of renal diseases could be classified into four categories: (1) Complications related to hematopoietic cell transplantation (conditioning regimen, immunosuppression, or posttransplantation complications), (2) podocytopathy, (3) membranous nephropathy, or (4) recurrence or persistence of original hematologic disease. Pathologic diagnoses included thrombotic microangiopathy, polyoma virus nephropathy, acute kidney injury/acute tubular necrosis, acute and chronic interstitial nephritis, minimal-change disease, "tip" variant of focal segmental glomerulosclerosis, membranous nephropathy, amyloidosis, and myeloma cast nephropathy. Membranous nephropathy, minimal-change disease, and amyloidosis were common causes of severe proteinuria. Because of the conditioning regimens, posttransplantation complications, and potential nephrotoxic agents used during hematopoietic cell transplantation, it was difficult to attribute the subsequent renal dysfunction to specific factors.

CONCLUSIONS

The renal biopsy remains essential for diagnosing the underlying injury that can affect one or more compartments of the kidney in this unique clinical setting.

Polyomavirus nephropathy in native kidneys and renal allografts: an update on an escalating threat

Polyomavirus nephropathy, also termed BK-virus nephropathy (BKN) after the main causative agent, the polyoma-BK-virus strain, is a significant complication after kidney transplantation. BKN is the most common viral infection that affects renal allografts with a prevalence of 1-9% on average 8-13 months post surgery. It can also occur sporadically in native kidneys. Viral nephropathy is caused by the (re)activation of latent BK viruses that enter into a replicative cycle under sustained and intensive immunosuppression. Pure productive kidney infections with JC- and SV-40 polyomaviruses are exceptionally rare. BKN is morphologically defined by the presence of intranuclear viral inclusion bodies in epithelial cells and tubular injury, which is the morphological correlate for renal dysfunction. Renal disease can progress through different histologic stages (from early BKN stage A to late fibrotic stage C) that carry prognostic significance; disease stages B and C often result in chronic kidney (allograft) dysfunction and end-stage renal disease. The clinical goal is to diagnose viral nephropathy in disease stage A and to limit chronic renal injury. Strategies to recognize, classify, and manage BKN are critically discussed including ancillary techniques for risk assessment and patient monitoring: (i) urine cytology and the search for so-called 'decoy cells'; (ii) PCR analyses for viral load measurements in the plasma and urine; and (iii) negative staining urine electron microscopy to identify viral particles.

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.

BK virus nephropathy in a heart transplant recipient: case report and review of the literature

The human polyomavirus BK virus (BKV) remains latent in the urinary tract and may be reactivated in immunocompromised states. BKV is noted to be the etiologic agent of polyomavirus-associated nephropathy (PVAN), which is a significant cause of allograft failure in renal transplant patients. Renal dysfunction following non-renal solid organ transplantation is common and is typically attributed to drug toxicity or patient comorbidities. In this article we describe a case of PVAN in the native kidneys of a heart transplant recipient and review the literature. Although this is only the fourth case reported, BKV nephropathy should be considered in the differential diagnosis of new renal failure following non-kidney solid organ transplantation, as early diagnosis of PVAN is necessary to prevent irreversible renal damage.