BK Polyomavirus-specific T cell immune responses in kidney transplant recipients diagnosed with BK Polyomavirus-associated nephropathy.

BACKGROUND: Adjustment of immunosuppression is the main therapy for BK polyomavirus (BKPyV)-associated nephropathy (BKPyVAN) after kidney transplantation (KT). Studies of BKPyV-specific T cell immune response are scarce. Here, we investigated BKPyV-specific T cell immunity in KT recipients diagnosed with BKPyVAN. METHODS: All adult KT recipients with BKPyVAN diagnosed at our institution from January 2017 to April 2018 were included. Laboratory-developed intracellular cytokine assays measuring the percentage of IFN-γ-producing CD4+ and CD8+ T cells, after stimulation with large-T antigen (LT) and viral capsid protein 1 (VP1), were performed both at the time of diagnosis and after adjustment of immunosuppression. RESULTS: We included 12 KT recipients diagnosed with BKPyVAN (7 proven, 4 presumptive, and 1 possible). Those with presumptive BKPyVAN had a median plasma BKPyV DNA load of 5.9 log10 copies/ml (interquartile range [IQR]: 4.9-6.1). Adjusted dosing of mycophenolic acid and tacrolimus with (86%) or without (14%) adjunctive therapies were implemented after diagnosis. There was a significantly higher median percentage of IFN-γ-producing CD4+ T cells to LT at a median of 3 (IQR: 1-4) months after adjustment of immunosuppression compared with at the time of diagnosis (0.004 vs. 0.015; p = 0.047). However, the difference between the median percentage of IFN-γ-producing CD4+ T cells to VP1 and CD8+ T cells to LT and VP1 did not reach statistical significance. Four (33%) patients achieved plasma BKPyV DNA clearance, and the remaining eight (67%) patients had persistent BKPyV DNAemia. Although eight (67%) patients developed allograft dysfunction, none required hemodialysis. CONCLUSIONS: We observed a marginal trend of BKPyV-specific CD4+ T cell recovery after adjustment of immunosuppression in KT recipients diagnosed with BKPyVAN. A further study would be benefited to confirm and better assess BKPyV-specific immune response after KT.

Currently recommended BK virus (BKV) plasma viral load cutoff of ≥4 log10/mL underestimates the diagnosis of BKV-associated nephropathy: a single transplant center experience.

BACKGROUND: BK virus (BKV)-associated nephropathy (BKVAN) is a major cause of renal dysfunction and graft loss in renal transplant recipients. Monitoring plasma BK viral load (BKVL) is the recommended screening tool to predict BKVAN. American Society of Transplantation (AST) guidelines define a BKVL of ≥4 log10/mL (10,000 copies) as presumptive BKVAN and recommend reduction in immunosuppression. We evaluated the clinical sensitivity of the quantitative BKV DNA assay in predicting risk for BKVAN using the AST-recommended BKVL cutoff. METHODS: In a retrospective, single-center study, all patients who underwent renal transplant at Henry Ford Hospital from January 2008 to August 2011 were analyzed (n = 490). Plasma BKVL Assay A (commercial large T antigen-based polymerase chain reaction [PCR]) was done in all patients. Renal biopsy was done if there was a rise in serum creatinine ≥0.5 mg from baseline. BKVAN was confirmed by biopsy. As a subset to this study, from the same cohort, data for a set of 20 consecutive Assays A and B (in-house VP1-based PCR assay) from 15 patients over a period of 3 months were collected. Differences in physicians' clinical decision-making (CDM) were analyzed between the 2 assays using chi-square test. RESULTS: A total of 413 patients met the inclusion criteria, of which 222 patients had BK viremia. Among the 248 patients who had a renal biopsy done, 31 (12.5%) were found to have BKVAN. Eleven of the 31 (35%) patients had BKVL consistently <4 log10/mL, and thus were not diagnosed to have BKVAN using the AST-recommended BKVL cutoff of ≥4 log10/mL. A total of 8 patients lost their graft owing to BKVAN, including 3 patients with BKVL <4 log10/mL. Using a cutoff point of plasma BKVL of ≥4 log10/mL, the sensitivity, specificity, positive predictive value, and negative predicative value of the PCR Assay A for the diagnosis of biopsy-proven BKVAN were 64.5%, 98.4%, 87.0%, and 94.5%, respectively, and for the diagnosis of presumptive nephropathy were found to be 76.6%, 99.4%, 95.8%, and 96.4%, respectively. In the second part of the study, presumptive nephropathy was detected in 8 samples using Assay A and 14 samples using Assay B. Six samples in Assay A would have led to no changes in the CDM in terms of reduction in immunosuppression. Kidney biopsy was carried out in 5 patients, 4 of whom had BKVAN and had Assay B log count of ≥5. If Assay A had been used in CDM, BKVAN would have been missed in 1 patient. CONCLUSION: Utilizing the current AST guideline cutoff of ≥4 log10 /mL, the PCR Assay A underestimated the diagnosis of BKVAN. Urgent standardization of the various BKVL assays and establishment of universal cutoff points is imperative to avoid BKVAN-related graft loss.

Treatment of BK virus-associated nephropathy with CMX001 after kidney transplantation in a young child.

NC, with renal failure secondary to bilateral dysplastic kidneys, received an LRD renal transplant (tx) at 17 months of age. Her early post-tx course was complicated by persistently elevated blood polyoma BK virus DNA loads. A protocol biopsy at six months post-transplant revealed BKVAN. Blood viral loads did not respond to decreased immunosuppression or treatment with ciprofloxacin and leflunomide. Six months post-tx, her serum creatinine began to rise and we sought experimental therapy to prevent the loss of her graft. At seven months post-tx, with FDA approval under an eIND, the patient was started on a 36-wk course of treatment with the investigational drug. The patient is now more than 24 months after stopping treatment with CMX. BKV viral DNA loads remain at low, but still detectable levels. Urine viral loads have declined, but remain elevated. EBV DNA loads become undetectable. The patient's serum creatinine has declined back to a baseline of 0.5-0.7 mg/dL and has been stable for two yr. Renal function was preserved in association with the use of CMX001 to treat BKV nephropathy in a young pediatric kidney transplant recipient. There were no serious adverse events associated with the use of CMX001. This novel medication may be of value in the treatment of BKVAN in pediatric renal transplant recipients.

BK polyomavirus: latency, reactivation, diseases and tumorigenesis.

The identification of the first human polyomavirus BK (BKV) has been over half century, The previous epidemiological and phylogenetic studies suggest that BKV prevailed and co-evolved with humans, leading to high seroprevalence all over the world. In general, BKV stays latent and symptomless reactivation in healthy individuals. BKV has been mainly interlinked with BKV-associated nephropathy (BKVAN) in kidney-transplant recipients and hemorrhagic cystitis (HC) in hematopoietic stem cell transplant recipients (HSCTRs). However, the mechanisms underlying BKV latency and reactivation are not fully understood and lack of extensive debate. As Merkel cell polyomavirus (MCV) was identified as a pathogenic agent of malignant cutaneous cancer Merkel cell carcinoma (MCC) since 2008, linking BKV to tumorigenesis of urologic tumors raised concerns in the scientific community. In this review, we mainly focus on advances of mechanisms of BKV latency and reactivation, and BKV-associated diseases or tumorigenesis with systematical review of formerly published papers following the PRISMA guidelines. The potential tumorigenesis of BKV in two major types of cancers, head and neck cancer and urologic cancer, was systematically updated and discussed in depth. Besides, BKV may also play an infectious role contributing to HIV-associated salivary gland disease (HIVSGD) presentation. As more evidence indicates the key role of BKV in potential tumorigenesis, it is important to pay more attention on its etiology and pathogenicity in vitro and in vivo.

Host and viral RNA dysregulation during BK polyomavirus infection in kidney transplant recipients.

Early detection of BK polyomavirus (BKPyV) infection in kidney transplant recipients (KTRs) would enhance their quality of life and save the allograft. Still, many patients lose their grafted kidneys because of this infection. BKPyV microRNAs (miRNAs) have been detected in KTRs during viral infection. BKPyV produces two mature miRNAs that are named BKV-miR-B1-5p and BKV-miR-B1-3p. Additionally, BKPyV associated nephropathy (BKVAN) in kidney transplanted patients cause changes in the expression level of host genes and miRNAs such as IFN-É£, BCLA2A1, has-miR-10, and has-miR-30a. BKVAN can alter viral genes and miRNAs expression level, too, like viral miRNAs and T-Ag. However, their potential value as viral infection markers and the regulatory network produced by their expression during viral-host interactions needs more consideration since there are no approved medications for treating BKPyV-related diseases in KTRs. Hence, it is vital to recognize complicated facts regarding the impact of BKPyV infection on the distribution of miRNAs and mRNAs within the host cell and the virus. This article is categorized under: Translation > Regulation RNA Processing > Processing of Small RNAs RNA in Disease and Development > RNA in Disease.

Intracellular Low Iron Exerts Anti-BK Polyomavirus Effect by Inhibiting the Protein Synthesis of Exogenous Genes.

BK polyomavirus (BKPyV) is a small double-stranded DNA virus and ubiquitous human pathogen that particularly affects immunocompromised individuals. Antiviral therapy for BKPyV is urgently needed. Intracellular irons have an important role in many viral infections, yet its contribution to BKPyV and replication has not been explored. In this study, we explored the interaction between BKPyV infection and intracellular iron and the inhibitory effect of iron depletion on BKPyV infection. By creating a low-intracellular-iron environment, we demonstrated that the iron-chelating-induced iron depletion inhibits BKPyV infection in primary renal tubular epithelial cells (RPTECs) and urinary bladder cancer cells (TCCSUP cells). Iron depletion exerts an inhibitory effect after BKPyV enters the nucleus, which might be due to the inhibition of the protein synthesis of exogenous genes in iron-depleted cells. Further exploration of the target proteins of iron-regulating viral infection could potentially be used to develop new strategies for urgently needed anti-BKPyV therapies. IMPORTANCE BKPyV poses a serious threat to the health of immunocompromised patients, and there are currently no curative drugs. Understanding the relationship between the virus and intracellular environment contributes to the discovery of antiviral targets. We demonstrate here that BKPyV is inhibited in cells with a low-iron environment. We also find that iron-chelating-induced iron depletion inhibits viral and exogenous protein synthesis. Further exploration of the target proteins of iron regulation could have great potential in developing new drugs against BKPyV and other viruses.

Human BK and JC polyomaviruses: Molecular insights and prevalence in Asia.

Polyomaviridae family consists of small circular dsDNA viruses. Out of the 14 human polyomaviruses described so far, BKPyV and JCPyV have been studied extensively since their discovery in 1971. Reportedly, both BKPyV and JCPyV are widely distributed across the globe with the frequency of 80-90 % in different populations. The primary infection of these viruses is usually asymptomatic and latent which is activated as a consequence of immunosuppression. Activated BKPyV and JCPyV viruses lead to the development of BK Virus Associated Nephropathy and Progressive Multifocal Leukoencephalopathy, respectively. Immense progress has been made during the last few decades regarding the molecular understanding of polyomaviruses. Epidemiology of polyomaviruses has also been studied extensively. However, most of the epidemiological studies have focused on European and American populations. Therefore, limited data is available regarding the geographical distribution of these potentially oncogenic viruses in Asian countries. In this article, we have presented a compendium of latest advances in the molecular understanding of polyomaviruses and their pathobiology. We also present a comprehensive review of published literature regarding the epidemiology and prevalence of BKPyV and JCPyV in Asian regions. For this purpose, a thorough search of available online resources was performed. As a result, we retrieved 24 studies for BKPyV and 22 studies for JCPyV, that describe their prevalence in Asia. These studies unanimously report high occurrence of both BKPyV and JCPyV in Asian populations. The available data from these studies was categorized into two groups: on the basis of prevalence (low, medium and high) and disease development (healthy and diseased). Altogether, Korean population hasbeen evidenced to possess highest frequency of BKPyV (66.7 %), while JCPyV was found to be most prevalent in Taiwan (88 %). Due to high and ubiquitous distribution of these viruses, frequent studies are required to develop a better understanding regarding the epidemiology and pathobiology of these viruses in Asia.

Management of BK-virus infection - Swedish recommendations.

BK-virus (BKV) associated nephropathy (BKVAN) and BKV associated haemorrhagic cystitis (HC) are complications of BKV infection/reactivation in renal and allogeneic haematopoietic stem cell transplantation (HSCT) patients, respectively. The task of how to manage these diseases was given to the chair by the Swedish Reference Group for Antiviral Therapy (RAV). After individual contributions by members of the working group, consensus discussions were held in a meeting on 23 January 2018 arranged by RAV. Thereafter, the recommendations were published in Swedish on November 2018. The current translation to English has been approved by all co-authors. High BKV serum levels suggest an increased risk for BKVAN and potential graft failure. For detection of BKVAN, careful monitoring of BKV DNA levels in serum or plasma is recommended the first year after renal transplantation and when increased creatinine serum levels of unknown cause are observed. Notably, a renal biopsy is mandatory for diagnosis. To reduce the risk for progression of BKVAN, there is no specific treatment, and tailored individual decrease of immunosuppression is recommended. For BKV-HC, BKV monitoring is not recommended, since BK-viruria frequently occurs in HSCT patients and the predictive value of BKV in plasma/serum has not been determined. However, the risk for BKV-HC is higher for patients undergoing myeloablative conditioning, having an unrelated, HLA-mismatched, or a cord blood donor, and awareness of the increased risk and early intervention may benefit the patients. Also for BKV-HC, no specific therapy is available. Symptomatic treatment, e.g. forced diuresis and analgesics could be of use.

BK Polyomavirus Virus Glomerular Tropism: Implications for Virus Reactivation from Latency and Amplification during Immunosuppression.

BK polyomavirus (BKPyV), or BKV infection, is ubiquitous and usually non-pathogenic, with subclinical infections in 80-90% of adults worldwide. BKV infection is often associated with pathology in immunocompromised individuals. BKV infection often is associated with renal impairment, including ureteral stenosis, hemorrhagic cystitis, and nephropathy. BKV infection is less commonly associated with pneumonitis, retinitis, liver disease, and meningoencephalitis. BKV is known to replicate, establish latency, undergo reactivation, and induce clinical pathology in renal tubular epithelial cells. However, recent in vitro studies support the notion that BKV has expanded tropism-targeting glomerular parenchymal cells of the human kidney, which could impact glomerular function, enhance inflammation, and serve as viral reservoirs for reactivation from latency during immunosuppression. The implications of BKV expanded tropism in the glomerulus, and how specific host and viral factors that would contribute to glomerular inflammation, cytolysis, and renal fibrosis are related to BKV associated nephropathy (BKVAN), have not been explored. The pathogenesis of BKV in human glomerular parenchymal cells is poorly understood. In this review, I examine target cell populations for BKV infectivity in the human glomerulus. Specifically, I explore the implications of BKV expanded tropism in the glomerulus with regard viral entry, replication, and dissemination via cell types exposed to BKV trafficking in glomerulus. I also describe cellular targets shown to be permissive in vitro and in vivo for BKV infection and lytic replication, the potential role that glomerular parenchymal cells play in BKV latency and/or reactivation after immunosuppression, and the rare occurrence of BKV pathology in glomerular parenchymal cells in patients with BKVAN.

An immunoinformatic approach to universal therapeutic vaccine design against BK virus.

In kidney transplant recipients (KTRs) long-term immunosuppression leads to BK virus (BKV) reactivation, with an increased incidence of BKV-associated pathologies and allograft rejection. The current approaches to limit BKV infection include a reduction in immunosuppression and use of anti-BKV drugs, which are clinically sub-optimal and lead to undesirable therapeutic outcomes. Here, we adopted an immune-based approach to augment the endogenous BKV specific T-cells. Using reverse vaccinology based in silico analyses, we designed a peptide-based multi-epitope vaccine for BKV (MVBKV). A major advantage of our approach is that the selected epitopes show an affinity towards all the 12 superfamilies of HLA class I alleles and 27 reference alleles of HLA class II. This suggests MVBKV's universal nature and its potential effectiveness in a wide-population base. To improve MVBKV's immunogenic properties, a synthetic Toll-like Receptor (TLR) 4 peptide ligand (RS09) was added to the final vaccine construct. The sequences of the individual epitopes were molecularly linked to form a 3D-stable synthetic protein. Overall, our immunoinformatic-based approach led to the design of a new MVBKV vaccine, which remains to be validated experimentally.

Management of BK Polyomavirus Infection in Kidney and Kidney-Pancreas Transplant Recipients: A Review Article.

BK virus (BKV) can cause graft dysfunction or failure in kidney transplant recipients and hemorrhagic cystitis in allogeneic hematopoietic stem cell transplant patients. BKV-associated nephropathy (BKVAN) emerged as a common complication in the late 1990s, probably due to the introduction of potent immunosuppressive agents. BKVAN occurred in up to 5% of kidney transplant recipients, with graft failure in up to 70%. Since universal implementation of effective screening and treatment strategies, BKV is no longer a common cause of graft failure; reported graft loss is only 0% to 5%. This article briefly describes BK virology, epidemiology, diagnosis, and management.

Research progress and application of donor-derived cell-free DNA in diagnosis and treatment of kidney transplantation / 器官移植

Early diagnosis and treatment of rejection after kidney transplantation play a critical role in alleviating allograft injury. Detection of donor-derived cell-free DNA (dd-cfDNA) could be performed based on the next-generation sequencing and other techniques. The content of DNA fragments derived from necrotic and apoptotic donor kidney tissues in circulating body fluids could be determined by concentration and absolute quantitative methods, which has application potential in monitoring allograft injury in clinical practice. Compared with traditional serum creatinine and other indicators, dd-cfDNA detection may monitor allograft injury from several weeks to months in advance, providing a "time window" for clinical treatment and delaying graft failure. Along with deepening research of dd-cfDNA in recent years, dd-cfDNA has captivated widespread attention due to its non-invasiveness, high sensitivity and real-time evaluation of therapeutic effect. In this article, current study evidence and conclusions related to multidimensional application of dd-cfDNA detection in diagnosis and treatment of kidney transplantation were reviewed, and the future research and clinical application direction of dd-cfDNA were discussed, aiming to provide reference for widespread application of dd-cfDNA detection in clinical practice in China.

The latest progress on JC virus infection after renal transplantation / 器官移植

JC virus (JCV) is a member of polyomaviridae family that infects approximately 70% of the population worldwide. JCV constantly stays in a latent state after the primary infection. In immunosuppressed individuals, especially under the circumstances of low cellular immune function, JCV may be reactivated and lead to severe clinical manifestations. In recent years, the correlation between JCV and complications after renal transplantation has captivated widespread attention. JCV-associated nephropathy (JCVAN) has been reported. Here, latest research progresses on the epidemiology, molecular biology, in vivo infection process, JCV and complications after renal transplantation, and the relationship between JCV and BKV were reviewed, aiming to provide reference for the adjustment of immunosuppressive regimen following renal transplantation.

Analysis of risk factors of high-level BK viruria after renal transplantation / 器官移植

Objective To analyze the risk factors of high-level BK viruria after renal transplantation and the significance in preventing BK virus-associated nephropathy (BKVAN). Methods Clinical data of 262 renal transplant recipients with regular follow-up data were retrospectively analyzed. According to the DNA load of BK virus, all recipients were divided into the high-level BK viruria group (n=35) and non-high-level BK viruria group (n=227). The incidence of high-level BK viruria after renal transplantation was summarized. The risk factors of high-level BK viruria after renal transplantation were analyzed by univariate analysis and multivariate analysis. Survival curve was delineated by Kaplan-Meier method, and survival analysis of recipients was performed. Results Among 262 renal transplant recipients, 35 cases developed high-level BK viruria with an incidence of 13.4%. The median time of occurrence of high-level BK viruria was 181 (126, 315) d. The incidence was the highest within 6 months after renal transplantation, gradually decreased from 6 months to 2 years, and then increased after 2 years. Univariate analysis showed that the history of antithymocyte globulin (ATG) treatment, acute rejection (AR), donation type and delayed graft function (DGF) were the risk factors of high-level BK viruria after renal transplantation (all P < 0.05). Multivariate Cox regression analysis demonstrated that donation after brain death followed by cardiac death (DBCD), AR and DGF were the independent risk factors of high-level BK viruria after renal transplantation. The 1-, 3- and 5-year survival rates of recipients with ATG treatment history, AR, DGF and donation type of DBCD were significantly lower than those with non-ATG treatment history, non-AR, non-DGF and other donation types [donation after brain death (DBD), donation after cardiac death (DCD) and living organ donation] respectively (all P < 0.05). Conclusions DBCD, AR and DGF are the independent risk factors of high-level BK viruria after renal transplantation. Strengthening the postoperative monitoring of these recipients and delivering early intervention may effectively prevent BKVAN.

Efficacy of leflunomide in the treatment of BK virus-associated nephropathy in transplant kidney / 医学研究生学报

Objective BK virus-associated nephropathy ( BKVAN) after kidney transplantation is a key factor that influence the prognosis of transplant kidney .To our knowledge , it is believed to be associated with immune suppression .We observed the cura-tive effect and influencing factorsof anti-rejection scheme that Leflunomide was administered instead of Mycophenolate Mofetil ( MMF) on transplant kidney BKVAN .. Methods This study included 15 kidney transplant recipients with pathologically confirmed BKVAN in Nanjing General Hospital of Nanjing Military Region form March 2007 to March 2013 .Leflunomide was administered instead of Myco-phenolate Mofetil ( MMF) .Serum creatinine level , renal allograft loss rate and side effects of leflunomide were monitored after medica-tion switch.The patients were divided into two groups , which were renal allograft loss group and renal allograft survival group , for fur-ther analyses . The differences between each groups in clinical characteristics as well as histochemical features of the transplanted kidneys were analyzed to determine the cause of renal allograft loss in patients with BKVAN . Results Six patients experienced renal al-lograft loss after switching to leflunomide and needed hemodialysis , and 9 patients had stable renal allograft function , renal allograft loss rate was 40.0%.Hyperuricemia occurred in 8 patients in the period before the medication switch and in 5 patients after the switch;a decrease in blood white cell orplateletcount was found in 2 patients during both periods;an increase in Alanine aminotransferase ( ALT) level occurred in one patient after the medication switch .There were no statistically significant differences in any of the above parame-ters before and after the medication switch.Compared to allograft survival group, serum creatinine level[(1.80 ±0.53)mg/dL vs (2.74 ±0.58)mg/dL, P=0.007], the number of B lymphocytes [(206.44 ±144.96) vs (439.67 ±267.77), P=0.047] and CD68[(588.44 ±271.80) vs (944.67 ±259.32), P=0.025] in renal allograft tissue were significantly higherin the allograft loss group. ConclusionLeflunomide is a safe and effective medication for BKVAN .Patients with significantly increased serum creatinine level might have a poorer prognosis .Significantly increased B lymphocytes and CD 68 cells in renal allograft tissue might indicate a poor prognosis.