[Analysis of BK virus infection in kidney transplant recipients]

Objective: To compare the infection of BK virus in the recipients of living donor(LD) kidney transplant and deceased donor(DD) kidney transplant. Methods: A total of 911 recipients who underwent kidney transplantation in the Organ Transplantation Research Institute of the 8th Medical Center of the People's Liberation Army General Hospital from January 2015 to August 2019 were enrolled in this study. The DNA copies of BK virus in urine and peripheral blood of kidney transplant recipients were detected by real-time quantitative PCR. The patients were divided into LD group (n=255) and DD group (n=656). BK virus infection in recipients with DD kidney transplant were compared with that in recipients of LD kidney transplant. Results: The BK virus positive rate in the urine of all subjects was 13.06%(119/911), and that in blood was 2.96% (27/911). The positive rate of BK virus in urine after kidney transplantation was significantly higher than that in blood(P<0.000 1). The positive rate in urine was 9.02% (23/255) in LD group, which was significantly lower than that of 14.63% (96/656) in DD group in the same period (χ(2)=5.097, P=0.012); The positive rate of BK virus infection in relatives group was 0.78% (2/255), which was significantly lower than that of 3.81% (25/656) in DD group (χ(2)=5.849, P=0.007). Conclusions: There was a significant difference in the infection rate of BK virus between the LD and DD group. The incidence of BK virus infection in kidney transplant recipients from DD was higher than that of from LD kidney transplant recipients.

Survey of BK Virus in Renal Transplant Recipients in Iran: A Systematic Review and Meta-Analysis

INTRODUCTION

BK virus (BKV) infection in renal transplant (RT) recipients can cause hemorrhagic cystitis, transient renal dysfunction, and BKV nephropathy (BKVN). The prevalence and significance of BKV in RT recipients remain to be clarified in the Iranian population. The purpose of this review is to summarize the overall prevalence of BKV infection in RT recipients from previously published studies in Iran.

METHODS

We systematically reviewed articles through a comprehensive search of the main electronic and Persian national databases up to November 2019.

RESULTS

The overall pooled prevalence of BKV infection among the Iranian population was 23% (95% CI; 15-33%). Comparing these studies revealed that the prevalence of BKV in plasma samples ranges from 3 to 40%, in renal biopsies 1-13%, and in urine samples 10-49%. Due to substantial heterogeneity among reported studies (I2 = 93%, p < 0.01), random-effect meta-analysis was performed. BKV infection rate was slightly higher in women than men (16%, p = 0.04 vs. 14%, p < 0.01, respectively). The majority of the studies employed real-time PCR (24%, I2 = 93, p < 0.01) and analyzed plasma samples alone or in combination with other types of specimens. BKV prevalence from 5 cities among the Iranian population showed a higher prevalence rate in Guilan.

CONCLUSION

Our analysis provides a preliminary estimate of the epidemiology of BKV infection in RT recipients in Iran. These results arouse a need for more epidemiological studies of BKV infection in different unanalyzed regions in Iran. Early detection of BKV in RT recipients helps timely nephropathy diagnosis and prevents graft loss.

The Role of HLA and KIR Immunogenetics in BK Virus Infection after Kidney Transplantation

BK virus (BKV) is a polyomavirus with high seroprevalence in the general population with an unremarkable clinical presentation in healthy people, but a potential for causing serious complications in immunosuppressed transplanted patients. Reactivation or primary infection in kidney allograft recipients may lead to allograft dysfunction and subsequent loss. Currently, there is no widely accepted specific treatment for BKV infection and reduction of immunosuppressive therapy is the mainstay therapy. Given this and the sequential appearance of viruria-viremia-nephropathy, screening and early detection are of utmost importance. There are numerous risk factors associated with BKV infection including genetic factors, among them human leukocyte antigens (HLA) and killer cell immunoglobulin-like receptors (KIR) alleles have been shown to be the strongest so far. Identification of patients at risk for BKV infection would be useful in prevention or early action to reduce morbidity and progression to frank nephropathy. Assessment of risk involving HLA ligands and KIR genotyping of recipients in the pre-transplant or early post-transplant period might be useful in clinical practice. This review summarizes current knowledge of the association between HLA, KIR and BKV infection and potential future directions of research, which might lead to optimal utilization of these genetic markers.

Outpatient haploidentical hematopoietic stem cell transplant using post-transplant cyclophosphamide and incidence of hemorrhagic cystitis

Introduction

Hemorrhagic cystitis (HC) is a common complication of haploidentical hematopoietic stem cell transplantation (haplo-HSCT), characterized by irritative symptoms of the urinary tract and a higher morbidity and mortality rate. The worldwide incidence is reported between 10% and 70%. The use of alkylating agents and BK viral infection are the most frequent etiologies. The aim of this study was to report the HC incidence in an outpatient haplo-HCST program with a reduced intensity-conditioning (RIC) regimen, cataloguing risk factors, complications and final outcomes.

Methods

The medical database of patients who received a haplo-HSCT between January 2012 and November 2017 was retrospectively analyzed. Demographic variables, general characteristics and HC incidence were included.

Results

One hundred and eleven patients were included, 30 (27%) of whom developed HC, most of them (70%) being grade II, with a 30-day (7–149) median time of post-transplant HC onset. The BK virus was detected in 71% of the urine samples analyzed. All HC patients responded to treatment, except two (6.6%), who died due to HC complications.

Conclusions

There was no difference in the HC incidence or severity, compared to that reported when performing haplo-HSCT in hospitalized patients, although the donor-recipient sex mismatch did relate to a higher HC incidence.

Treatment protocols for BK virus associated hemorrhagic cystitis after hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) represents a vital curative choice for many disease. However its outcome can be hampered by a variety of transplant associated complications. Hemorrhagic cystitis (HC) considered as one of the major difficulties after HSCT. HC symptoms comprise hematuria, dysuria, burning during urination, urinary frequency, urgency and incontinency, abdominal or suprapubic pain, urinary obstruction, and renal or bladder damage. There are a lot of causes for HC development. BK virus reactivation is one of the major causes of HC after HSCT. There is still no standard and approved treatment protocol for BK virus associated HC (BKV-HC). Treatment of HC is according to the local standard operating procedures, depending on the cause and severity. In this study we will review the current treatments available for this disease. We have divided the therapeutic procedures into 5 categories including conservative therapy, complimentary options, surgical procedures, pharmacological treatments and adoptive cell therapy. We believe that comparing the advantages and disadvantages of different therapies make it easier to choose the best treatment protocol. In addition, we had a greater focus on adoptive cell therapy, because it is a relatively new introduced method and might be a logical alternative to conventional treatments for refractory patients. In total, no definitive recommendation is possible for current available treatments because these procedures have only been utilized sporadically in a limit number of patients. Furthermore, a number of treatment options are only experimental and definitely need more effort.

Analysis of risk factors influencing the BK polyomavirus replication in patients with ESRD waiting for kidney transplantation

BACKGROUND

Since the pre-transplant status affects the renal transplantation success and ultimately the survival rate, identifying the probable risk factors that increase the chance of BK virus replication in end-stage renal disease patients can be included in proposing proper surveillance guidelines during pre and post-transplantation.

METHODS

A descriptive cross-sectional study was performed by collecting plasma samples from 192 ESRD patients undergoing hemodialysis for at least 3 months. Quantitative Real-time PCR assay was used to detect and measure the BK viral load. Demographic and clinical characteristics of the patients who had BK viremia were documented.

RESULTS

14 (7.3%) out of our 192 participants had BK virus viremia (95%CI 4.2%-11.6%). Demographic characteristics including etiology of ESRD and underlying diseases, mean duration and frequency of dialysis, co-infection with HBV and HCV did not affect the virus replication, since the difference between patients with BK virus viremia and BK virus negative individuals was not statistically significant. However, the statistical significance of the mean age of men with BKV and without BK virus viremia was found (OR: 3.42, P = 0.02 95%CI 0.86-13.61). Also, multiple regression analyses of some other parameters revealed that old age, high body mass index and male gender can be predictive factors of BK virus viremia in ESRD patients.

CONCLUSION

Based on our findings, elderly male had higher chance of being exposed to BK virus viremia. Some other demographic characteristics such as a high BMI, old age and gender (male) can increase the risk of BK viremia in patients with ESRD prior to kidney transplantation.

Clinical Efficacy of Intravenous Immunoglobulin for BK Polyomavirus-Associated Nephropathy After Living Kidney Transplantation

Purpose

BK polyomavirus (BKPyV)-associated nephropathy (BKPyVAN) is one of the most difficult infections to be treated after kidney transplantation. Although patients with BKPyVAN usually received a reduction of immunosuppressive agents, the majority of these patients undergo the loss of the graft kidney without any effective treatment afterward. Therefore, development of more effective therapy for BKPyVAN is eagerly expected.

Patients and Methods

Among patients who underwent a kidney transplantation between January 2016 and April 2019 at our hospital, there were five cases of BKPyVAN. After the initial diagnosis, all patients discontinued administration of mycophenolate mofetil (MMF), which was not enough to diminish decoy cells in urine cytology test. Therefore, all patients received additional intravenous immunoglobulin (IVIG) (100 mg/kg/day) therapy for five days and were evaluated for the therapeutic effect of IVIG with immunohistochemical examination using re-biopsy samples of the graft kidney.

Results

After IVIG therapy, 2 cases showed negative decoy cells in urine and 3 cases showed a drastic decrease of plasma BK virus load. Importantly, simian virus (SV) 40 large T antigens diminished after IVIG administration in all cases, which degraded polyomavirus nephropathy classification.

Conclusion

Although it is difficult to treat BKPyVAN after kidney transplant, IVIG therapy was considered to a promising treatment to improve severity of BKPyVAN especially in cases that dose reduction of immunosuppressive agents was ineffective.

Development and validation of a risk assessment tool for BKPyV Replication in allogeneic stem cell transplant recipients

BACKGROUND

BK polymavirus (BKPyV), a member of the family Polyomaviridae, is associated with increased morbidity and mortality in allogeneic stem cell transplant recipients.

METHODS

In our previous retrospective study of 2477 stem cell transplant patients, BKPyV replication independently predicted chronic kidney disease and poor survival. In this study, using the same cohort, we derived and validated a risk grading system to identify patients at risk of BKPyV replication after transplantation in a user-friendly modality. We used 3 baseline variables (conditioning regimen, HLA match status, and underlying cancer diagnosis) that significantly predicted BKPyV replication in our initial study in a subdistribution hazard model with death as a competing risk. We also developed a nomogram of the hazard model as a visual aid. The AUC of the ROC of the risk-score-only model was 0.65. We further stratified the patients on the basis of risk score into low-, moderate-, and high-risk groups.

RESULTS

The total risk score was significantly associated with BKPyV replication (P < .0001). At 30 days after transplantation, the low-risk (score ≤ 0) patients had a 9% chance of developing symptomatic BKPyV replication, while the high-risk (score ≥ 8) of the population had 56% of developing BKPyV replication. We validated the risk score using a separate cohort of 1478 patients. The AUC of the ROC of the risk-score-only model was 0.59. Both the total risk score and 3-level risk variable were significantly associated with BKPyV replication in this cohort (P < .0001).

CONCLUSIONS

This grading system for the risk of symptomatic BKPyV replication may help in early monitoring and intervention to prevent BKPyV-associated morbidity, mortality, and kidney function decline.

Resurgence of BK virus following Covid-19 in kidney transplant recipients

Kidney transplant recipients have been supposed vulnerable to severe Covid-19 infection, due to their comorbidities and immunosuppressive therapies. Mild-term complications of Covid-19 are currently unknown, especially in this population. Herein, we report two cases of BKV replication after non-severe SARS-CoV-2 infection. The first case was a 59-year-old man, transplanted 3 months ago, with recent history of slight BKV viremia (3.3 log₁₀ DNA copies/ml). Despite strong reduction of maintenance immunosuppression (interruption of mycophenolic acid and important decrease of calcineurin inhibitors), BKV replication largely increased after Covid-19 and viremia persisted at 4.5 log copy/ml few months later. The second case was a 53-year-old woman, transplanted 15 years ago. She had a recent history of BKV cystitis, which resolved with a decrease of MPA dosage. Few weeks after SARS-CoV-2 infection, she presented recurrence of lower urinary tract symptoms. Our reports highlight that SARS-CoV-2 infection, even without severity, could disrupt immune system and particularly lymphocytes, thus leading to viral replication. Monitoring of viral replications after Covid-19 in kidney transplant recipients could permit to confirm these preliminary observations.

Serum Albumin Level Before Kidney Transplant Predicts Post-transplant BK and Possibly Cytomegalovirus Infection

Introduction

Opportunistic viral infections cause extensive morbidity and mortality in kidney transplant recipients (KTRs). Low serum albumin levels before and after transplant have been associated with negative outcomes. However, it is uncertain whether serum albumin levels before transplantation are associated with the risk for post-transplantation opportunistic BK polyomavirus (BKV) or cytomegalovirus (CMV).

Methods

We reviewed all KTRs transplanted at our institution between 1 January 2005 and 31 December 2015 with serum albumin measured within 45 days before transplantation in a retrospective observational cohort study. Selected patients were stratified into 3 groups: normal albuminemia (≥3.5 g/dl), moderate hypoalbuminemia (3.49–2.5 g/dl), and severe hypoalbuminemia (<2.5 g/dl). Patients were observed for post-transplantation BKV or CMV according to standard of care.

Results

We included 1717 patients in this study; 72.3% had normal serum albumin, 26.3% had moderate hypoalbuminemia, and 1.5% had severe hypoalbuminemia. Moderate and severe hypoalbuminemia incurred a higher risk for BKV compared with normal serum albumin levels in univariable analysis (moderate hypoalbuminemia: hazard ratio [HR] = 1.5; 95% confidence interval [CI], 1.14–1.90; P = .003); severe hypoalbuminemia: HR = 2.15; 95% CI, 1.01–4.56; P = 0.05). Although not significant after multivariable adjustment, there was still 18% increased risk in moderate hypoalbuminemia and 64% in severe hypoalbuminemia for BKV compared with the normal albumin group. Moderate hypoalbuminemia was associated with a higher risk for CMV infection than normal serum albumin levels in multivariable analysis, although it was not statistically significant (HR = 1.15; 95% CI, 0.36–3.64; P = 0.81).

Conclusions

These findings suggest that pretransplantation hypoalbuminemia is associated with a higher risk for post-transplantation BKV and possibly CMV. More intense screening is warranted for these viruses in recipients with pretransplant hypoalbuminemia.

Comparative Evaluation of In-House and Commercial Real-Time PCR Methods for the Detection of the BK and JC Viruses in Clinical Samples

Aim  The two most common human polyomaviruses are the BK (BKV) and JC viruses (JCV). Diseases associated with polyomavirus usually occur in cases of severe cellular immunosuppression. BKV and JCV can cause many diseases, especially if they are reactivated in an immunosuppressed host. The aim of this study is to compare and evaluate the results of real-time polymerase chain reaction (PCR) methods targeting the small and large T gene regions of the viral genome, considering polymorphisms occurring in the viral genome of BKV and JCV.

Materials and Methods  Urinary specimens of 82 patients were taken from immunosuppressed patient and sent to molecular microbiology laboratory of Meram Medical Faculty. The small t gene was investigated using a commercial kit (LightMix, Roche) by real-time PCR method. Large T gene was investigated by using the optimized in-house real-time PCR method. Sequence analysis was accepted as the standard method.

Results  BKV positivity was detected in 9 samples and JCV positivity in 61 samples by real-time PCR method specific to small t gene region; BKV positivity in 21 samples and JCV positivity in 67 samples were determined by real-time PCR method specific to the large T gene region. Statistically, there was a significant difference for BKV, but not significant difference for JCV detection between the two methods.

Conclusion  Different polymorphisms in the target gene regions were responsible for the different outcomes obtained from this study. With this sensitivity and specificity, in-house PCR method which we used is a candidate for routine diagnosis.

BK Polyomavirus-Specific CD8 T-Cell Expansion In Vitro Using 27mer Peptide Antigens for Developing Adoptive T-Cell Transfer and Vaccination

BACKGROUND

BK polyomavirus (BKPyV) remains a significant cause of premature kidney transplant failure. In the absence of effective antivirals, current treatments rely on reducing immunosuppression to regain immune control over BKPyV replication. Increasing BKPyV-specific CD8 T cells correlate with clearance of BKPyV DNAemia in kidney transplant patients. We characterized a novel approach for expanding BKPyV-specific CD8 T cells in vitro using 27mer-long synthetic BKPyV peptides, different types of antigen-presenting cells, and CD4 T cells.

METHODS

Langerhans cells and immature or mature monocyte-derived dendritic cells (Mo-DCs) were generated from peripheral blood mononuclear cells of healthy blood donors, pulsed with synthetic peptide pools consisting of 36 overlapping 27mers (27mP) or 180 15mers (15mP). BKPyV-specific CD8 T-cell responses were assessed by cytokine release assays using 15mP or immunodominant 9mers.

RESULTS

BKPyV-specific CD8 T cells expanded using 27mP and required mature Mo-DCs (P = .0312) and CD4 T cells (P = .0156) for highest responses. The resulting BKPyV-specific CD8 T cells proliferated, secreted multiple cytokines including interferon γ and tumor necrosis factor α, and were functional (CD107a+/PD1-) and cytotoxic.

CONCLUSIONS

Synthetic 27mP permit expanding BKPyV-specific CD8 T-cell responses when pulsing mature Mo-DCs in presence of CD4 T cells, suggesting novel and safe approaches to vaccination and adoptive T-cell therapies for patients before and after kidney transplantation.

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.

Indoleamine 2,3-Dioxygenase Is Involved in Interferon Gamma's Anti-BKPyV Activity in Renal Cells

Reactivation of BK polyomavirus (BKPyV) infection is frequently increasing in transplant recipients treated with potent immunosuppressants and highlights the importance of immune system components in controlling viral reactivation. However, the immune response to BKPyV in general and the role of antiviral cytokines in infection control in particular are poorly understood. Here, we investigated the efficacy of interferons (IFN) alpha, lambda and gamma with regard to the BKPyV multiplication in Vero cells. Treatment with IFN-gamma inhibited the expression of the viral protein VP1 in a dose-dependent manner and decreased the expression of early and late viral transcripts. Viral inhibition by IFN-gamma was confirmed in human cells (Caki-1 cells and renal proximal tubular epithelial cells). One of the IFN-stimulated genes most strongly induced by IFN-gamma was the coding for the enzyme indoleamine 2,3 dioxygenase (IDO), which is known to limit viral replication and regulates the host immune system. The antiviral activity induced by IFN-gamma could be reversed by the addition of an IDO inhibitor, indicating that IDO has a specific role in anti-BKPyV activity. A better understanding of the action mechanism of these IFN-gamma-induced antiviral proteins might facilitate the development of novel therapeutic strategies.

Patient-individual cancer cell lines and tissue analysis delivers no evidence of sequences from DNA viruses in colorectal cancer cells

Background

Several DNA viruses are highly suspicious to have oncogenic effects in humans. This study investigates the presence of potentially oncogenic viruses such as SV40, JCV, BKV and EBV in patient-derived colorectal carcinoma (CRC) cells typifying all molecular subtypes of CRC.

Methods

Sample material (gDNA and cDNA) of a total of 49 patient-individual CRC cell lines and corresponding primary material from 11 patients, including normal, tumor-derived and metastasis-derived tissue were analyzed for sequences of SV40, JVC, BKV and EBV using endpoint PCR. In addition, the susceptibility of CRC cells to JCV and BKV was examined using a long-term cultivation approach of patient-individual cells in the presence of viruses.

Results

No virus-specific sequences could be detected in all specimens. Likewise, no morphological changes were observed and no evidence for viral infection or integration could be provided after long term CRC cell cultivation in presence of viral particles.

Conclusions

In summary, the presented data suggest that there is no direct correlation between tumorigenesis and viral load and consequently no evidence for a functional role of the DNA viruses included into this analysis in CRC development.

T-cell adoptive immunotherapy for BK nephropathy in renal transplantation

Introduction

BK virus (BKPyV) nephropathy occurs in 1%‐10% of kidney transplant recipients, with suboptimal therapeutic options.

Case

A 54‐year‐old woman received a transplant in March 2017. BKPyV was detected at 1.5 × 10² copies/mL within a month, necessitating halving of mycophenolate and addition of leflunomide. Allograft histology in December showed polyomavirus nephropathy treated with intravenous immunoglobulin and cessation of mycophenolate. In February 2018, cidofovir and ciprofloxacin were commenced. In April, tacrolimus was reduced while introducing everolimus. A second graft biopsy in August showed increasing polyoma virus infection and a subsequent biopsy in September for worsening renal function showed 30% of tubular reactivity for simian virus 40 (SV40). Allogeneic BKPyV‐reactive T cells were generated from the patient's daughter and infused over 10 sessions starting late September. The fourth allograft biopsy in November 2018 demonstrated involvement of BKPyV in 50% of tubules. Allograft function continued to decline, requiring hemodialysis from December 2018. Allograft nephrectomy after 6 months showed <1% SV40 in preserved tubules and 80% interstitial fibrosis.

Discussion

We conclude that the T‐cell adoptive immunotherapy reduced BKPyV load significantly despite extensive infection, but attendant fibrosis and tubular atrophy led to graft failure. Early intervention with T‐cell therapy may prove efficacious in BKPyV nephropathy.

Combined association of recipient killer cell immunoglobulin-like haplotype AA and donor HLA-C*07 gene with BK virus associated nephropathy in kidney transplant patients

Kidney transplant recipient killer cell immunoglobulin-like receptors (KIR) genotype and HLA-C status of their donors have been separately associated with BK virus-associated nephropathy (BKVAN) and BK virus infection. Our aim was to determine whether different combinations of recipients KIR genes and donor HLA-C ligands influence the risk of BKVAN. Retrospective case-control study included 23 recipients with BKVAN and 46 recipients with persistently negative BK virus. Donor HLA-C*07 positivity was associated with lower odds for BKVAN, recipients bearing KIR haplotype AA or lacking any activating KIR genes were more frequent in BKVAN while recipient/donor combination HLA-C*07 negative/KIR AA positive was significantly associated with BKVAN. Our study complements and confirms results from several previously published studies, suggesting potential clinical usefulness.

Hemorrhagic Cystitis after Haploidentical Transplantation with Post-Transplantation Cyclophosphamide: Protective Effect of MESNA Continuous Infusion

Hemorrhagic cystitis (HC) is an important complication after haploidentical hematopoietic stem cell transplantation (haplo-HSCT) with post-transplantation cyclophosphamide (PT-CY). Sodium 2-mercaptoethanesulfonate (MESNA) can prevent bladder injury when given with PT-CY. However, the best way to deliver MESNA is not known. This study assessed the incidence of HC after haplo-HSCT with PT-CY with 2 different methods of MESNA administration. The cumulative incidence of HC was lower in patients who received MESNA as a continuous infusion compared with those who received it as an intermittent bolus (5.6% versus 27.8%; P = .01). MESNA administration as an infusion was associated with a lower risk of developing HC (hazard ratio [HR], .19; 95% confidence interval [CI], .04 to .86; P = .02) on univariate analysis. This effect remained significant after adjustment in multivariate analysis (HR, .21; 95% CI, .04 to .88; P = .03). MESNA delivered as a continuous infusion is a simple and potentially useful way to prevent HC after PT-CY.

Effectiveness of Immune Checkpoint Inhibitors in Transplant Recipients with Progressive Multifocal Leukoencephalopathy

Antibodies against PD1 have been used to treat progressive multifocal leukoencephalopathy (PML), a rare brain disease caused by JC virus. We used these antibodies (nivolumab) to treat PML in 3 kidney transplant recipients. All died within 8 weeks of diagnosis. Hence, nivolumab did not improve PML outcome after solid organ transplantation.

Glibenclamide inhibits BK polyomavirus infection in kidney cells through CFTR blockade

BK polyomavirus (BKPyV) is a ubiquitous pathogen in the human population that is asymptomatic in healthy individuals, but can be life-threatening in those undergoing kidney transplant. To-date, no vaccines or anti-viral therapies are available to treat human BKPyV infections. New therapeutic strategies are urgently required. In this study, using a rational pharmacological screening regimen of known ion channel modulating compounds, we show that BKPyV requires cystic fibrosis transmembrane conductance regulator (CFTR) activity to infect primary renal proximal tubular epithelial cells. Disrupting CFTR function through treatment with the clinically available drug glibenclamide, the CFTR inhibitor CFTR₁₇₂, or CFTR-silencing, all reduced BKPyV infection. Specifically, time of addition assays and the assessment of the exposure of VP2/VP3 minor capsid proteins indicated a role for CFTR during BKPyV transport to the endoplasmic reticulum, an essential step during the early stages of BKPyV infection. We thus establish CFTR as an important host-factor in the BKPyV life cycle and reveal CFTR modulators as potential anti-BKPyV therapies.

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BK polyomavirus (BKPyV) is life-threatening in those undergoing kidney transplant.

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BKPyV requires CFTR to infect primary kidney cells.

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Disrupting CFTR function pharmacologically reduces BKPyV infection.

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CFTR is required during BKPyV transport to the endoplasmic reticulum.

Opportunistic Infections in Transplant Patients

Transplants have become common with excellent patient and graft outcomes owing to advances in surgical technique, immunosuppression, and antimicrobial prophylaxis. In 2017, 34,770 solid organ transplants were performed in the United States. For solid organ transplant recipients, infection remains a common complication owing to the regimens required to prevent rejection. Opportunistic infections, which are infections that are generally of lower virulence within a healthy host but cause more severe and frequent disease in immunosuppressed individuals, typically occur in the period 1 month to 1 year after transplantation. This article focuses on opportunistic infections in the solid organ transplant recipient.

Does the Evidence Support the Existence of the Simian Polyomavirus SV40 Vp4 Viroporin?

The simian polyomavirus SV40 was reported to express Vp4, an N-terminally truncated form of the minor capsid proteins Vp2 and Vp3. Since a missense mutation of the putative Vp4 start codon (Vp2M228I) was found to give reduced progeny release and delayed lysis, Vp4 was claimed to be a viroporin. However, two independent research groups, including our own, were unable to replicate these findings. In contrast, we found no Vp4 expression in SV40-infected cells and no reduction in progeny release for Vp4-deficient virus, and finally, we found that the single amino acid substitution unavoidably introduced into the overlapping Vp2/Vp3 genes during Vp4 mutagenesis reduced early steps but not virus release. Remarkably, the existence of the viroporin Vp4 still seems to be widely accepted, which presumably is preventing important research on polyomavirus release. With this perspective, we will review and comment on the most important experiments that led to the disputed announcement of the viroporin Vp4.

BK polyomavirus diversity-Why viral variation matters

BK polyomavirus (BKPyV or BKV) is a non-enveloped, circular double-stranded DNA virus that may exceed 80% seroprevalence in adults. BKV infection typically occurs during childhood, and the majority of adults are latently infected. While BKV infection is rarely associated with clinical disease in most individuals, in immunosuppressed individuals, reactivation may cause kidney (BK-associated nephropathy) or bladder (hemorrhagic cystitis and ureteral stenosis) injury. No antiviral therapies have been approved for the treatment of BKV infection. Reducing immunosuppression is the most effective therapy, although this is not feasible in many patients. Thus, a robust understanding of viral pathogenesis and viral diversity remains important for the development of future therapeutic strategies. Studies of BKV diversity are quite sparse compared to other common viral infections; thus, much of our understanding of BVK variability and evolution relies heavily analogous studies of other viruses such as HIV or viral hepatitis. We provide a comprehensive review of BKV diversity at the population and individual level with careful consideration of how viral variability may impact viral replication, pathogenesis, tropism, and protein function. We also discuss a number of outstanding questions related to BK virus diversity that should be explored rigorously in future studies.

Effects and long-term follow-up of using umbilical cord blood-derived mesenchymal stromal cells in pediatric patients with severe BK virus-associated late-onset hemorrhagic cystitis after unrelated cord blood transplantation

This is a retrospective study to evaluate the efficacy and safety of umbilical cord blood-derived mesenchymal stromal cells (MSCs) for the treatment of pediatric patients with severe BK virus-associated late-onset hemorrhagic cystitis (BKV-HC) after unrelated cord blood transplantation (UCBT). Thirteen pediatric patients with severe BKV-HC from December 2013 to December 2015 were treated with MSCs. The number of MSCs transfused in each session was 1 × 10⁶ /kg once a week until the symptoms improved. The median follow-up time was 1432 (89-2080) days. The median frequency of MSC infusion was 2 (1-3), with eight cured cases and five effective cases; the total efficacy rate was 100%. The copy number of urine BKV DNA was 4.43 (0.36-56.9) ×10⁸ /mL before MSC infusion and 2.67 (0-56.3) ×10⁸ /mL after MSC infusion; the difference was not significant (P = .219). There were no significant differences in the overall survival, disease-free survival, and the incidence of relapse and acute and chronic graft-versus-host disease between the MSC infusion group and non-MSC infusion group. There was also no significant difference in the cytomegalovirus, Epstein-Barr virus (EBV), and fungal and bacterial infection rates between the two groups. Although umbilical cord blood-derived MSCs do not reduce the number of BKV DNA copies in the urine, the cells have a high efficacy rate and minimal side effects in treating severe BKV-HC after UCBT among pediatric patients. MSCs do not affect the rates of relapse, long-term infection, or survival of patients with leukemia.

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.