Pretransplant BKV-IgG serostatus and BKV-specific ELISPOT assays to predict BKV infection after kidney transplantation.

Introduction: Polyomavirus (BKV) infection can lead to major complications and damage to the graft in kidney transplant recipients (KTRs). We investigated whether pretransplant BK serostatus and BK-specific cell-mediated immunity (CMI) predicts post-transplant BK infection. Methods: A total of 93 donor-recipient pairs who underwent kidney transplantation (KT) and 44 healthy controls were examined. Assessment of donor and recipient BKV serostatus and BKV-CMI in recipients was performed prior to transplantation using BKV-IgG ELISA and BKV-specific IFN-g ELISPOT assays against five BK viral antigens (LT, St, VP1, VP2, and VP3). BK viremia was diagnosed when blood BKV-DNA of 104 copies/mL or more was detected during follow-up periods. Results: Anti-BKV IgG antibody was detected in 74 (79.6%) of 93 KTRs and in 68 (73.1%) of 93 KT donors. A greater percentage of KTRs who received allograft from donors with high levels of anti-BKV IgG had posttransplant BK viremia (+) than KTRs from donors with low anti-BKV IgG (25.5% [12/47] vs. 4.3% [2/46], respectively; P = 0.007). Pretransplant total BKV-ELISPOT results were lower in BK viremia (+) patients than in patients without viremia (-) 20.5 [range 9.9-63.6] vs. 72.0 [43.2 - 110.8]; P = 0. 027). The sensitivity and specificity of the total BKV-ELISPOT assay (cut-off ≤ 53 spots/3×105 cells) for prediction of posttransplant BK viremia were 71.4 (95% CI: 41.9-91.6) and 54.4 (42.8-65.7), respectively. The combination of high donor BKV-IgG, low recipient BKV-IgG, and low total BKV-ELISPOT results improved specificity to 91.1%. Discussion: Our study highlights the importance of pretransplant BKV-IgG serostatus and BKV-specific CMI in predicting posttransplant BKV infection in KTRs. The combination of high donor BKV-IgG, low recipient BKV-IgG, and low total BKV-ELISPOT results predicted BK viremia after KT. Pretransplant identification of patients at highrisk for BK viremia could enable timely interventions and improve clinical outcomes of KTRs.

Risk factors for BK virus infection in DCD donor kidney transplant recipients.

Background: BK virus infection after kidney transplantation can negatively impact the prognosis of patients. However, current risk factor analyses primarily focus on BK virus nephropathy, while BK viruria and BK viruria progressing to BK viremia receive less attention. This study aims to analyze the risk factors associated with BK viruria and BK viruria progressing to BK viremia in recipients of donation after cardiac death (DCD), with the goal of facilitating early intervention. Methods: Donor characteristics and clinical data of recipients before and after transplantation were evaluated, and logistic univariate and multivariate analyses were performed to determine the risk factors associated with BK viruria and the progression of BK viruria to BK viremia. Additionally, machine learning techniques were employed to identify the top five features associated with BK viruria evolving into BK viremia. Results: During a median follow-up time of 1,072 days (range 739-1,418), 69 transplant recipients (15.6% incidence rate) developed BK viruria after transplantation, with 49.3% of cases occurring within 6 months post-transplantation. Moreover, 19 patients progressed to BK viremia. Donor age [OR: 1.022 (1.000, 1.045), p = 0.047] and donor procalcitonin (PCT) levels [0.5-10 ng/ml; OR: 0.482 (0.280, 0.828), p = 0.008] were identified as independent risk factors for BK viruria. High BK viruria [OR: 11.641 (1.745, 77.678), p = 0.011], recipient age [OR: 1.106 (1.017, 1.202), p = 0.018], and immunoinduction regimen [ATG; OR: 0.063 (0.006, 0.683), p = 0.023] were independent risk factors for BK viruria progressing to BK viremia. Machine learning analysis confirmed the importance of high BK viruria, recipient age, and immunoinduction regimen (ATG) in predicting the progression of BK viruria to BK viremia. Conclusion: The development and progression of BK virus in DCD kidney transplant recipients is influenced by multiple factors. Early intervention and treatment could potentially extend the lifespan of the transplanted organ.

BKPyV DNAemia in Kidney Transplant Recipients Undergoing Regular Screening: A Single-Centre Cohort Study.

Infection with BK polyomavirus (BKPyV) is a common opportunistic infection after kidney transplantation (KT) and may affect graft function. We aimed to determine the incidence, risk factors, and clinical outcomes of BKPyV DNAemia in a prospective cohort of 601 KT recipients transplanted from 2012 to 2020. BKPyV PCR on plasma was performed at days 60, 90, 180, 270, and 360 post-KT. Any BKPyV DNAemia was defined as a single BKPyV DNA of ≥1000 copies/mL. Severe BKPyV DNAemia was defined as two consecutive BKPyV DNA of ≥10,000 copies/mL. Cumulative incidences were investigated using the Aalen-Johansen estimator, and the risk factors were investigated in Cox proportional hazard models. The incidence of any BKPyV DNAemia and severe BKPyV DNAemia was 21% (18-25) and 13% (10-16) at one year post-KT, respectively. Recipient age > 50 years (aHR, 1.72; 95% CI 1.00-2.94; p = 0.049), male sex (aHR, 1.96; 95% CI 1.17-3.29; p = 0.011), living donors (aHR, 1.65; 95% CI 1.03-2.74; p = 0.045), and >3 HLA-ABDR mismatches (aHR, 1.72; 95% CI 1.01-2.94; p = 0.046) increased the risk of severe BKPyV DNAemia. Any BKPyV DNAemia was associated with an increased risk of graft function decline (aHR, 2.26; 95% CI 1.00-5.12; p = 0.049), and severe BKPyV DNAemia was associated with an increased risk of graft loss (aHR, 3.18; 95% CI 1.06-9.58; p = 0.039). These findings highlight the importance of BKPyV monitoring post-KT.

CC Genotype of GNAS c.393C>T (rs7121) Polymorphism Has a Protective Effect against Development of BK Viremia and BKV-Associated Nephropathy after Renal Transplant

The GNAS gene encodes the alpha-subunit of the stimulatory G-protein (Gαs) in humans and mice. The single-nucleotide polymorphism of GNAS, c.393C>T, is associated with an elevated production of Gαs and an increased formation of cyclic adenosine monophosphate (cAMP). In the present study, we analyzed the effect of this GNAS polymorphism on a renal allograft outcome. We screened a cohort of 436 renal allograft recipients, who were retrospectively followed up for up to 5 years after transplant. GNAS genotypes were determined with polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) assays. The 393T allele was detected in 319 (73%) recipients (113 recipients with TT and 206 with CT genotype) and the CC genotype in 117 (27%). The CC genotype was associated with a significantly lower frequency of BK viremia (CC, 17 recipients (15%); T 84 (26%)); p = 0.01; TT, 27 vs. CC, 17, p = 0.07; TT, 27 vs. CT, 57, p = 0. 46; CT, 57 vs. CC, 17, p = 0.01) and BKV-associated nephropathy (CC, 3 recipients (3%); T, 27 (8%); p = 0.03; TT,10 vs. CC, 3, p = 0.04; TT, 10 vs. CT,17, p = 0.85; CT, 17 vs. CC,3, p = 0.04) after transplant. BKV-associated nephropathy-free survival was significantly better among CC genotype carriers than among T allele carriers (p = 0.043; TT vs. CC, p = 0.03; CT vs. CC, p = 0.04; TT vs. CT, p = 0.83). Multivariate analysis indicated an independent protective effect of the CC genotype against the development of both BK viremia (relative risk. 0.54; p = 0.04) and BKV-associated nephropathy after renal transplant (relative risk. 0.27; p = 0.036). The GNAS 393 CC genotype seems to protect renal allograft recipients against the development of BK viremia and BKV-associated nephropathy.

Risk factors for progression from low level BK dnaemia to unfavorable outcomes after BK management via immunosuppressive reduction.

BACKGROUNDS: Effective management of BK viremia (BKPyV-DNAemia) in kidney transplant recipients (KTRs) involves regular monitoring and adjustment of immunosuppression. With this strategy, the majority of patients will clear BK or have ongoing, but non-significant, low-level BKPyV-DNAemia. However, despite adjustments, some will develop more severe sequelae of BK including BKPyV-DNAemia >5 log10 copies/mL and BK nephropathy, and others may develop de novo DSA (dnDSA) or acute rejection (AR). METHODS: This was a single-center study of KTRs transplanted at the University of Wisconsin-Madison between 01/01/2015 and 12/31/2017. In this study, we sought to elucidate characteristics associated with the progression of BKPyV-DNAemia to unfavorable outcomes after decreasing immunosuppressive medications for the management of BK viremia as described in consensus guidelines. RESULTS: A total of 224 KTRs fulfilled our selection criteria; 118 (53%) resolved or had persistent low DNAemia, 64 (28%) had severe BK/nephropathy, and 42 (19%) developed dnDSA or AR. In multivariable analysis, female gender (HR: 2.05; 95% CI: 1.08-3.90; P = .02); previous rejection (HR: 2.90; 95% CI: 1.04-8.12; P = .04), and early infection (HR: 0.81; 95% CI: 0.72-0.90; P < .001) were associated with the development of severe BK/nephropathy. Conversely, non-depleting induction at transplant (HR: 2.06; 95% CI: 1.03-4.11; P = .03), HLA mismatches >3 (HR: 2.27; HR: 1.01-5.06; P = .04), and delayed graft function (HR: 4.14; 95% CI: 1.12-15.28; P = .03) were associated with development of dnDSA and/or rejection. CONCLUSION: Our study suggests that almost half of KTRs with BKPyV-DNAemia managed by our immunosuppressant adjustment protocol progress unfavorably. Identification of these risk factors could assist the frontline clinician in creating an individualized immunosuppressive modification plan potentially mitigating negative outcomes.

A pilot study of immunosuppression resumption following BK viremia resolution.

BACKGROUND: Immunosuppression reduction for BK viremia is associated with de novo humoral responses, which are a risk factor for rejection and graft loss. In this pilot project, we tested a protocol of immunosuppression resumption to standard dose after viral clearance for optimal protection against humoral immunity in patients undergoing treatment for BK viremia. METHODS: Thirty-six consecutive kidney transplant recipients who developed BK viremia from 7/1/2014 to 11/18/2016 underwent immunosuppression reduction. After 4 weeks of absent viremia, mycophenolate mofetil (MMF) was increased by 500mg/day every 2 weeks up to standard dosage, followed by increase of tacrolimus trough levels to 5-7 ng/mL. If viremia recurred during the increase, immunosuppression was reduced in this same stepwise fashion, with stepwise increase again after 2 months of negative viremia. RESULTS: Mean tacrolimus trough level (ng/mL) was 8.3 ± 2.7 at viremia onset, 5.3 ± 3.6 at resolution, and 5.6 ± 2.0 at study end date. Mean daily dose (mg) of MMF was 1574 ± 355 at onset, 910 ± 230 at resolution, and 1377 ± 451 at study end date. Only one patient developed low level viremia recurrence (peak 2875 copies/mL) during the period of immunosuppression resumption that ultimately resolved. CONCLUSIONS: The results of our pilot project indicate that following BK viremia resolution, resumption of standard immunosuppression can be achieved safely without BK viremia recurrence. Larger trials with long-term follow up are required to determine whether such an approach improves long-term graft survival.

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.

Transplant renal artery stenosis in a child with BK nephropathy.

TRAS and BK nephropathy are known complications of RT, but the association between both has not been reported. A 2-year-old girl underwent a deceased donor renal transplant from a 20-year-old donor, along with bilateral native nephrectomies. She had a DGF due to a renal artery thrombus and required thrombectomy with re-anastomosis. Heparin and aspirin were used. Immunosuppressive agents included thymoglobulin, steroid, tacrolimus, and MMF. CMV and EBV DNA PCRs were negative, but she developed BK viremia at 2 months with stable allograft function. Immunosuppression was reduced, and leflunomide was initiated. Blood pressures were well controlled on low-dose amlodipine. Five months after RT, she presented with hypertensive emergency, following a respiratory infection, and required dialysis for oliguric acute kidney injury. Allograft biopsy showed evidence of BK nephropathy. Immunosuppression was further minimized. Doppler renal US and renal artery duplex studies were both suggestive of TRAS. Angiogram showed severe proximal anastomotic TRAS (>95% occlusion). PTA with stenting was done with immediate improvement in the blood flow and reduction in the pressure gradient. BPs and renal function normalized. Ten months post-RT, she remains normotensive with stable renal function and resolution of BK viremia. Although ureteral stenosis and nephropathy are known to occur with BK infection, TRAS is an interesting association and possibly suggest the tropism of BK virus to the vascular endothelial cells. Timely recognition and management of both is important to prevent uncontrolled hypertension and allograft dysfunction.

Prospective Analysis of Hemorrhagic Cystitis and BK Viremia in Allogeneic Hematopoietic Stem Cell Transplantation

Objective: BK virus (BKV) infection has been shown to be related to hemorrhagic cystitis (HC) in allogeneic hematopoietic stem cell transplantation (allo-HSCT). There are conflicting data regarding the association between BKV titers in plasma and clinical disease as well as the risk factors for BKV-related HC. Our aim is to study the risk factors and relationship with plasma BK viral load for development of HC in a prospective analysis. Materials and Methods: We prospectively evaluated 59 patients who received allo-HSCT between 2014 and 2016 by quantitative BK virus polymerase chain reaction (PCR) (Altona Diagnostics, Germany) from blood samples at days 0, 30, 60, and 90 after allo-HSCT. The patients were monitored for signs and symptoms of HC. Results: HC was diagnosed in 22 patients (37%) at a mean of 100 days (range: 0-367 days). In multivariate analysis, the usage of cyclophosphamide (sub-distribution hazard ratio [sdHR]: 7.82, confidence interval [CI]: 1.375-39.645, p=0.02), reactivated CMV (sdHR: 6.105, CI: 1.614-23.094, p=0.008), and positive BKV viremia (sdHR: 2.15, CI: 1.456-22.065, p=0.01) significantly increased the risk of developing HC. Patients with higher viral loads at day 30 and day 60 were diagnosed with more severe HC (p<0.001). Median BK viral loads of >101.5 copies/mL at day 0 (sensitivity 0.727, specificity 0.875), >98.5 copies/mL at day 30 (sensitivity 0.909, specificity 0.875), and >90.0 copies/mL at day 60 (sensitivity 0.909, specificity 0.875) were indicative of HC. Conclusion: Our study showed that administration of cyclophosphamide, CMV reactivation, and BK virus positivity were associated with HC. Plasma BK virus PCR titers at days 0, 30, and 60 after transplant were sensitive tools for predicting clinically proven HC.

Impact of human leukocyte antigen and calculated panel reactive antibody on BK viremia in kidney transplant recipients: A single-center experience and literature review.

BACKGROUND: The aim of this retrospective analysis was to investigate the effect of human leukocyte antigen (HLA) and calculated panel reactive antibody (cPRA) on BK virus activation as evidenced by BK viremia (BKV). PATIENTS AND METHODS: At our institution, 649 kidney transplant patients were screened for BKV from 2009 to 2017. Patients were considered to have BKV if they had >10 000 copies/mL of BK DNA in their blood. Donor and recipient HLA and cPRA, demographic, clinical and laboratory data, as well as immunosuppressive medications were collected. RESULTS: We identified 122 BK positive and 527 BK negative patients. Only 25% of the patients had cPRA of 20% or more, and 64% had more than three HLA-A, -B, and -DR mismatches. In both univariate and multivariate analyses, male gender, age, and maintenance of steroid therapy significantly increased the risk of BKV (P = 0.005, 0.005 and <0.001, respectively). The degree of cPRA and the individual HLA allele and HLA allele matching did not significantly affect BKV. CONCLUSION: Neither the degree of HLA mismatching nor cPRA appears to affect BKV. Moreover, no specific HLA allele, HLA allele matching, or cPRA were associated with BKV.

Reactivation of BK polyomavirus during pregnancy, vertical transmission, and clinical significance: A meta-analysis.

BACKGROUND: Studies have shown conflicting results on the prevalence and the risks of BK reactivation among pregnant women. In addition, the prevalence of vertical transmission and its clinical significance during pregnancy are not well studied. OBJECTIVES: The study's aims were (1) to investigate the prevalence, and (2) to assess the risk of BK Polyomavirus reactivation and its clinical significance in pregnant women and fetuses. STUDY DESIGN: A literature search was performed using MEDLINE, EMBASE and Cochrane Database from inception through May 31, 2017. We included studies that reported prevalence, relative risks, odds ratios, or hazard ratios of BK Polyomavirus reactivation during pregnancy. Pooled odds ratios (ORs) and 95% CI were calculated using a random-effect model. The protocol for this study is registered with PROSPERO (International Prospective Register of Systematic Reviews; no. CRD42017063919). RESULTS: 17 observational studies with a total of 2553 pregnant women were enrolled. The estimated prevalence of BK seropositivity and BK in urine (viruria) among pregnant women were 79.2% (95%CI: 69.6%-86.4%) and 18.9% (95%CI: 10.4%-31.8%). When compared to non-pregnant women, the pooled ORs of BK seropositivity and BK viruria in pregnant women were 1.84 (95%CI: 1.05-3.22) and 6.02 (95%CI: 2.43-14.92), respectively. The estimated prevalence of positive BK-specific IgM antibody in cord blood was 4.9% (95%CI: 0.5%-36.2%). The data on the fetal effects of BK virus were limited. Although BK was detected in fetal organs, available data suggested no association between BK infection and adverse consequences such as miscarriage during pregnancy or childhood malignancy. CONCLUSION: Our meta-analysis demonstrates a significantly increased risk of BK Polyomavirus reactivation during pregnancy. Although vertical transmission can occur with an overall estimated prevalence of 4.9%, there are currently no data suggesting harm to pregnant women and fetuses from BK Polyomavirus.

Relationship between metabolic rate of tacrolimus and BK virus infection early after renal transplantation / 器官移植

Objective To investigate the relationship between the metabolic rate of tacrolimus (FK506) and BK virus infection early after renal transplantation. Methods Eighty recipients undergoing allogenic renal transplantation in Institute of Organ Transplantation of the 309thHospital of Chinese People's Liberation Army were recruited in this study. The polymorphism of cytochrome P450 (CYP) 3A5 gene was detected in 80 recipients. All patients were divided into fast metabolism group ( CYP3A5*1/*3 and CYP3A5*1/*1 genotypes, n=38) and slow metabolism group ( CYP3A5*3/*3 genotype, n=42) based on the gene detection results. The distribution of CYP3A5 genotypes in 80 recipients was analyzed. The metabolic rate [concentration/dose ratio (C/D value)] of FK506 was statistically compared between two groups. The incidence of BK virus infection events [BK viruria, BK viremia and BK virus nephropathy(BKVN)] within postoperative 6 months were compared between two groups. Results Among 80 recipients, 5 cases (6%) were detected with CYP3A5*1/*1 genotype, 33 (41%) with CYP3A5*1/*3 genotype, and 42 (53%) with CYP3A5*3/*3 genotype. Among the 160 alleles in 80 recipients, 117 CYP3A5*3 allele were identified, suggesting that the mutation rate of CYP3A5*3 allele was 73.1%. In the fast metabolism group, the C/D values at postoperative 1, 3, and 6 months were significantly lower than those in the slow metabolism group (all P<0.01). The incidence rates of BK viruria in the fast and slow metabolism groups were 37% and 29%, 18% and 2% for BK viremia, and 3% and 0 for BKVN, respectively. In the fast metabolism group, the incidence of BK virenia was significantly higher than that in the slow metabolism group (P=0.02). The incidence of BK viruria and BKVN did not significantly differ between two groups (both P>0.05). Conclusions According to the CYP3A5 genotyping outcomes, the recipients with a high metabolic rate of FK506 have a high risk of BK viremia early after renal transplantation.

Clinical study on the effect of BK virus infection on renal allograft function after renal transplantation / 器官移植

Objective To analyze the impairment of renal allograft function in renal transplant recipients caused by BK virus infection after renal transplantation. Methods Clinical data of 210 recipients who underwent allogenic renal transplantation and received BK virus monitoring regularly were analyzed retrospectively. The incidence of BK viruria, viremia and BK virus nephropathy (BKVN) after renal transplantation was summarized. The effect of BK virus infection on renal allograft function and prognosis of renal allograft function after the removement of BK virus were analyzed. Results Among the 210 recipients, there were 46 cases with pure viruria, 46 cases with viremia complicated with viruria and 7 cases with BKVN confirmed by pathological biopsy. The level of serum creatinine (Scr) in the recipients with viremia after renal transplantation was linearly related to BK viral load in urine and blood (r=0.594, 0.672, both P<0.01). The level of Scr increased significantly when BK viral load in blood of the recipients with viremia was found positive for the first time, and increased continuously after viremia sustained. And the level of Scr decreased slightly when blood viral load turned to negative after treatment, but still significantly higher than before virus infection. All the above differences were statistically significant (all P<0.05). Compared with the basic level, there was no significant difference in the level of Scr of recipients with pure viruria during positive viruria (all P>0.05). Conclusions It will impair the renal allograft function when BK viremia occurs after renal transplantation, and it is necessary to monitor viral infection regularly. Once the blood BK virus is found positive, it shall be implemented immediately to reduce the intensity of immunosuppression as the preferred clinical intervention.

BK viremia surveillance and outcomes in simultaneous pancreas-kidney transplant recipients.

BACKGROUND: While screening for asymptomatic BK viremia (BKV) has been well studied in isolated kidney transplant recipients, there is a paucity of published outcomes in simultaneous pancreas-kidney (SPK) transplant recipients who underwent BKV screening followed by pre-emptive reduction in immunosuppression. METHODS: This is a single-center, retrospective review of 31 consecutive SPK recipients who were transplanted over a 5-year period following the initiation of a serum BKV screening protocol. RESULTS: BK viremia developed in 11 (35.5%) patients, and all patients achieved complete viral clearance following reduction in immunosuppression. Two patients (6.5%) developed BK virus nephropathy, but both had preserved allograft function. One patient developed mild rejection of the kidney allograft following clearance of BKV, and two patients developed mild rejection of the pancreas allograft after reduction in immunosuppression, but there were no kidney or pancreas allograft losses due to rejection. The development of BK viremia did not impact overall patient survival or kidney and pancreas allograft survival. CONCLUSION: Screening asymptomatic SPK recipients for BKV followed by reduction in maintenance immunosuppression appears to be an effective strategy to prevent kidney allograft dysfunction and graft loss due to BK virus nephropathy, without compromising pancreas allograft outcomes.

De Novo Collapsing Glomerulopathy in Renal Allograft in Association with BK Virus Nephropathy in a Child and Stabilization of Renal Function by Elimination of Viremia.

Well-recognized association between HIV 1 infection and collapsing glomerulopathy (CG) raises the possibility that intrarenal infection by other viruses may also contribute to the development of this lesion in native or post-transplant kidneys. There is evidence in literature about association of these lesions with cytomegalovirus, Epstein-Barr virus, hepatitis C virus, and parvovirus B19 infections. Here, we present a case report of post-transplant BK virus nephropathy in a male child who was found to have CG in subsequent biopsy 2 months later. His renal function and proteinuria were stabilized on elimination of viremia.

Ureteral stent duration and the risk of BK polyomavirus viremia or bacteriuria after kidney transplantation.

OBJECTIVES: Ureteral stents are used in kidney transplantation (KTX) to decrease post-operative complications, but they are associated with BK polyomavirus viremia (BKV). Our primary outcome was to determine the association between ureteral stent duration and BKV. Secondary outcome measures were the association between bacteriuria and stent duration or use of ureteral stent strings. METHODS: Between January 2010 and January 2015, 403 patients underwent KTX at the Virginia Mason Medical Center and met inclusion criteria. Stent duration was classified as short (<3 weeks) or long (>3 weeks). Multivariate logistic regression models were created to assess for factors associated with BKV. The covariates in the BKV model were chosen a priori based on stent duration and risk factors previously described in the literature. RESULTS: Ureteral stents were placed in 304 (75.4%) transplants. Stent strings were left attached in 166 (54.6%) patients. On multivariate analyses, long stent duration was significantly associated with increased risk of BKV compared with no stent (odds ratio [OR] 1.92, P=.044, 95% confidence interval [CI] 1.04-3.74). Short stent duration was not associated with BKV. Sixty-two (15.4%) patients had bacteriuria. Bacteriuria was associated with female gender (OR 2.77, P<.001, 95% CI 1.58-4.95), and there was a dose-dependent effect with stent duration compared with no stent-short duration (OR 2.46, P=.049, 95% CI 1.05-6.49) and long duration (OR 3.58, P=.004, 95% CI 1.58-9.25). Stent strings were not associated with either complication. CONCLUSIONS: The association between ureteral stents and BKV may be dose dependent.

Evaluation of leflunomide for the treatment of BK viremia and biopsy proven BK nephropathy; a single center experience.

BACKGROUND: BK virus reactivation is a significant complication following renal transplantation that can result in graft failure. Reduction of immunosuppression and substitution of leflunomide for mycophenolate mofetil (MMF) has been used to treat this entity. OBJECTIVES: To evaluate the use of leflunomide in BK viremia (BKV) and biopsy proven BK nephropathy (BKN) in kidney and kidney-pancreas transplant recipients. PATIENTS AND METHODS: We retrospectively reviewed 28 kidney and kidney-pancreas transplant recipients who had received leflunomide for BKV from January 2006 to November 2012. Demographics, time to BKV diagnosis, biopsy findings, rejection episodes, and laboratory data were recorded. RESULTS: The average (mean ± SD) time to BKV from time of transplant was 316.1 ± 368.0 days (62-1708 days). At time of diagnosis, 64% of patients had their maintenance immunosuppression reduced. The indications for leflunomide administration were; BKV and biopsy proven acute rejection (BPAR) (50%), biopsy proven BKN (18%), or persistent BKV (25%). Therapeutic levels (50-100 mcg/mL) were achieved in only 54% of patients, and 60% of them had required a leflunomide dose of at least 60 mg/day. BK virus was cleared from the serum on average of 151 ± 145.2 days (17-476 days). At study commencement, 29% of patients had remained on leflunomide due to persistent BKV. CONCLUSIONS: In our study, most patients required at least a 60 mg daily dose of leflunomide to achieve therapeutic levels and to clear the virus compared to the standard 40 mg daily dose. Delaying therapy may result in progressive BKV and BKN.

Incidence and Factors Associated with De Novo DSA After BK Viremia in Renal Transplant Recipients.

BK polyomavirus infection and de novo donor-human leukocyte antigen (HLA) specific antibodies (dnDSA) are two well-known and distinct complications occurring after kidney transplantation. Recent literature suggests an association between the two events. This study aims to examine the relationship between BK viremia (BKV) and dnDSA and to identify potential risk factors for dnDSA following BKV in kidney transplant recipients. A retrospective review of 1019 recipients from Houston Methodist Hospital was conducted. All patients underwent routine screening for BKV and dnDSA. Median follow-up was 44 months. BKV was detected in 186 (18%) patients at a median of 107 (82-205) days post-transplant. dnDSA occurred in 283 (28%) patients at a median of 272 (62-575) days post-transplant. Of the 69 dnDSA-positive/BKV-positive patients, dnDSA detection occurred after BKV onset in 46 patients. Thus, 46 (28%) previously DSA-negative patients later became dnDSA-positive following BKV, not significantly different from the rate seen in BKV-negative patients (26%; p=0.5). Median time to DSA detection following BKV onset was 232 days (interquartile range, 119-460) post-BKV detection. Multivariate analysis revealed a greater number of HLA mismatches and viral clearance as risk factors for development of dnDSA following BKV, whereas delayed graft function was associated with a lower risk of dnDSA. In conclusion, despite being considered a result of over-immunosuppression, BKV can still be followed by dnDSA in a substantial proportion of patients. Monitoring for dnDSA in patients being managed for BKV may be warranted.

Kidney retransplantation for BK virus nephropathy with active viremia without allograft nephrectomy.

BK virus nephropathy is an important cause of kidney allograft failure. Retransplantation has been successfully performed for patients with previous allograft loss due to BK virus nephropathy; however, whether allograft nephrectomy and viral clearance are required prior to retransplantation is controversial. Some recent studies have suggested that retransplantion can be successfully achieved without allograft nephrectomy if viremia is cleared prior to retransplant. The only published experience of successful retransplantation in the presence of active viremia occurred in the presence of concomitant allograft nephrectomy of the failing kidney. In this report, we describe a case of successful repeat kidney transplant in a patient with high-grade BK viremia and fulminant hepatic failure without concomitant allograft nephrectomy performed under the setting of a simultaneous liver-kidney transplant.

Brincidofovir for polyomavirus-associated nephropathy after allogeneic hematopoietic stem cell transplantation.

Polyomavirus-associated nephropathy (PVAN) is common in patients who have undergone kidney transplantation and has been reported in hematopoietic stem cell (HSC) transplant recipients. Aside from reduction of immunosuppression, few therapeutic options exist for treatment of PVAN. We report a case of PVAN in a severely immunocompromised allogeneic HSC transplant recipient that was treated with brincidofovir without reduction of immunosuppression. We review our institutional experience of PVAN in HSC transplantation and discuss the potential use of brincidofovir for treatment.