BK polyomavirus in solid organ transplantation-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

Incidence, risk factors, management strategies, and outcomes of antibody-mediated rejection in pediatric kidney transplant recipients-a multicenter analysis of the Cooperative European Paediatric Renal Transplant Initiative (CERTAIN)

BACKGROUND

This study by the Cooperative European Paediatric Renal Transplant Initiative (CERTAIN) was designed to determine the incidence, risk factors, current management strategies, and outcomes of antibody-mediated rejection (ABMR) in pediatric kidney transplant recipients (pKTR).

METHODS

We performed an international, multicenter, longitudinal cohort study of data reported to the Cooperative European Paediatric Renal Transplant Initiative (CERTAIN) registry. Three hundred thirty-seven pKTR from 21 European centers were analyzed. Clinical outcomes, including kidney dysfunction, rejection, HLA donor-specific antibodies, BK polyomavirus-associated (BKPyV) nephropathy, and allograft loss, were assessed through 5 years post-transplant.

RESULTS

The cumulative incidence of de novo donor-specific class I HLA antibodies (HLA-DSA) post-transplant was 4.5% in year 1, 8.3% in year 3, and 13% in year 5; the corresponding data for de novo class II HLA-DSA were 10%, 22.5%, and 30.6%, respectively. For 5 years post-transplant, the cumulative incidence of acute ABMR was 10% and that of chronic active ABMR was 5.9%. HLA-DR mismatch and de novo HLA-DSA, especially double positivity for class I and class II HLA-DSA, were significant risk factors for ABMR, whereas cytomegalovirus (CMV) IgG negative recipient and CMV IgG negative donor were associated with a lower risk. BKPyV nephropathy was associated with the highest risk of graft dysfunction, followed by ABMR, T-cell mediated rejection, and older donor age.

CONCLUSIONS

This study provides an estimate of the incidence of de novo HLA-DSA and ABMR in pKTR and highlights the importance of BKPyV nephropathy as a strong risk factor for allograft dysfunction.

Predicting graft survival in paediatric kidney transplant recipients using machine learning

BACKGROUND

Identification of factors that affect graft survival in kidney transplantation can increase graft survival and reduce mortality. Artificial intelligence modelling enables impartial evaluation of clinician bias. This study aimed to examine factors that affect the survival of grafts in paediatric kidney transplantation through the use of machine learning.

METHODS

A retrospective review was conducted on records of paediatric patients who underwent kidney transplantation between 1994 and 2021 and had post-transplant follow-up > 12 months. The nearest neighbour method was used to impute missing fields from a total of 48 variables in the dataset. Models including Naive Bayes, logistic regression, support vector machine (SVM), multi-layer perceptron, and XGBoost were trained to predict graft survival. The study used 80% of the patients for training and the remaining 20% for testing. Modelling success was evaluated based on accuracy and F1 score metrics.

RESULTS

The study analysed 465 kidney transplant recipients. Of these, 56.7% were male. The mean age at transplantation was 12.08 ± 5.01 years. Of the kidney transplants, 73.1% (n = 339) were from living donors, 34.5% (n = 160) were pre-emptive transplants, and 2.2% (n = 10) were second-time transplants. The machine learning model identified several features associated with graft survival, including antibody-mediated rejection (+ 0.7), acute cellular rejection (+ 0.66), eGFR at 3 years (+ 0.43), eGFR at 5 years (+ 0.34), pre-transplant peritoneal dialysis (+ 0.2), and cadaveric donor (+ 0.2). The successes of the logistic regression and SVM models were similar. The F1 score was 91.9%, and accuracy was 96.5%.

CONCLUSION

Machine learning can be used to identify factors that affect graft survival in kidney transplant recipients. By expanding similar studies, risk maps can be created prior to transplantation.

Early clearance of BK polyomavirus-DNAemia among kidney transplant recipients may lead to better graft survival

INTRODUCTION

BK polyomavirus (BKPyV)-DNAemia is a common complication in kidney transplant recipients (KTRs). The significance of achieving viral clearance at different time intervals is not well understood.

METHODS

All adult KTRs transplanted between January 1, 2015 and December 31, 2017 who developed BKPyV-DNAemia were included. Outcomes were analyzed based on persistent clearance of BKPyV-DNAemia at 3-month intervals up to 2 years after initial detection, and for recipients with persistent BKPyV-DNAemia at last follow-up. Uncensored graft failure, death-censored graft failure (DCGF), and a composite outcome of DCGF or fall in estimated glomerular filtration rate (eGFR) by ≥50% from the time of initial BKPyV-DNAemia were outcomes of interest.

RESULTS

Of 224 KTRs with BKPyV-DNAemia, 58 recipients (26%) achieved viral clearance by 3 months after initial detection, 105 (47%) by 6 months, 120 (54%) by 9 months, 141 (63%) by 12 months, 155 (69%) by 15 months, 167 (75%) by 18 months, 180 (80%) by 21 months, and 193 (86%) by 24 months. Nine recipients (4%) had persistent BKPyV-DNAemia at last follow-up. Compared to recipients who achieved viral clearance by 3 months, those who achieved clearance by 6 months (adjusted odds ratio [aOR]: 3.15; 95% confidence interval [CI]: 1.22-8.12; p = .02) and 9 months (aOR: 3.69; 95% CI: 1.02-13.43; p = .04) had significantly increased risk for uncensored graft failure. There was no significant association between time to viral clearance and DCGF or composite outcomes.

CONCLUSIONS

We found a trend of increased risk for uncensored graft failure among those who cleared BKPyV-DNAemia more slowly. Aiming to clear viremia early, without risking rejection, may be beneficial for allograft function and patient morbidity and mortality.

Novel intervention based on an individualized bundle of care to decrease infection in kidney transplant recipients

BACKGROUND

Infection remains a relevant complication after kidney transplantation (KT). A well-established strategy in modern medicine is the application of bundles of evidence-based practice in clinical settings. The objective of this study is to explore the application of a personalized bundle of measures aimed to reduce the incidence of infection in the first 12 months after KT.

METHODS

A single-center prospective cohort of 148 patients undergoing KT between February 2018 and September 2019 that received an individualized infection prevention strategy was compared to a preintervention cohort (n = 159). The bundle comprised a review of the patient's immunization history, infection risk by country of origin, screening for latent tuberculosis infection (LTBI), antimicrobial prophylaxis, and immunological assessment. Individualized recommendations were accordingly provided at a scheduled visit at day +30 after transplantation.

RESULTS

The intervention cohort showed a higher compliance rate with the recommended vaccine schedule, screening for geographically restricted infections and LTBI, and intravenous immunoglobulin and vitamin D supplementation (p values <.001). The 1-year incidence rate of infection was lower in the intervention cohort (42.6% vs. 57.9%; p value = .037), as was the rate of infection-related hospitalization (17.6% vs. 32.1%; p value = .003) and the incidence of severe bacterial infection. There were no differences in graft rejection or mortality rates between groups.

CONCLUSIONS

A multifaceted intervention, including a bundle of evidence-based practices, enhanced compliance with recommended preventive measures and was correlated with a reduction in the 12-month incidence of infection after KT.

Preferences in treating polyomavirus infection in kidney transplant recipients: A discrete choice experiment with patients, caregivers, and clinicians

BACKGROUND

Treatment strategies for BK polyomavirus (BKPyV) infection in kidney transplant recipients are heterogeneous among clinicians. We aimed to identify the treatment preferences of key stakeholders for BKPyV infection and measure the trade-offs between treatment outcomes.

METHODS

Adult kidney transplant recipients, caregivers, and clinicians were eligible to participate in a discrete choice experiment between February 2021 and June 2022. The five treatment-related attributes were achieving viral clearance and optimal graft function, as well as reducing the risk of graft loss, acute rejection, and complications. Results were analyzed using multinomial logistic models.

RESULTS

In total, 109 participants (57 kidney transplant recipients, 10 caregivers, and 42 health professionals) were included. The most important attribute was the risk of graft loss, followed by side effects and acute rejection. As the risk of graft loss increased, all participants were less inclined to accept an assigned treatment strategy. For instance, if graft loss risk was increased from 1% to 50%, the probability of uptake of a treatment strategy for BKPyV infection was reduced from 87% to 3%.

CONCLUSION

Graft loss is the predominant concern for patients, caregivers, and health professionals when deciding on the treatment for BKPyV infection, and should be included in intervention trials of BKPyV infection.

A randomized, placebo-controlled, dose-escalation phase I/II multicenter trial of low-dose cidofovir for BK polyomavirus nephropathy

BACKGROUND

BK polyomavirus-associated nephropathy (BKPyVAN) is an important cause of allograft dysfunction and failure in kidney transplant recipients (KTRs) and there are no proven effective treatments. Case reports and in vitro data support the potential activity of cidofovir against BK polyomavirus (BKPyV).

METHODS

We report the results of a phase I/II, double-blind, placebo-controlled randomized dose-escalation trial of cidofovir in KTRs with biopsy-confirmed BKPyVAN and estimated glomerular filtration rate ≥30 mL/min. Intravenous cidofovir (0.25 mg/kg/dose or 0.5 mg/kg/dose) or placebo was administered on days 0, 7, 21, and 35, with final follow-up through day 49.

RESULTS

The trial was prematurely discontinued due to slow accrual after 22 KTRs had completed the study. Cidofovir was safe and tolerated at the doses and duration studied. The proportion of subjects with any adverse event (AE) was similar between groups (9/14 [64%] in the combined cidofovir dose groups and 6/8 [75%] in the placebo group); 84% of AEs were mild. BKPyV DNAemia reduction by day 49 was similar between groups (>1 log10 reduction in (2/9 [22.2%] of 0.25 mg/kg group, 1/5 [20%] of 0.5 mg/kg group, and 2/8 [25%] of placebo group).

CONCLUSIONS

These preliminary results indicate that low-dose cidofovir was safe and tolerated but had no significant BKPyV-specific antiviral effect in KTRs with BKPyVAN.

Serum and urine nucleic acid screening tests for BK polyomavirus-associated nephropathy in kidney and kidney-pancreas transplant recipients

BACKGROUND

BK polyomavirus-associated nephropathy (BKPyVAN) occurs when BK polyomavirus (BKPyV) affects a transplanted kidney, leading to an initial injury characterised by cytopathic damage, inflammation, and fibrosis. BKPyVAN may cause permanent loss of graft function and premature graft loss. Early detection gives clinicians an opportunity to intervene by timely reduction in immunosuppression to reduce adverse graft outcomes. Quantitative nucleic acid testing (QNAT) for detection of BKPyV DNA in blood and urine is increasingly used as a screening test as diagnosis of BKPyVAN by kidney biopsy is invasive and associated with procedural risks. In this review, we assessed the sensitivity and specificity of QNAT tests in patients with BKPyVAN.

OBJECTIVES

We assessed the diagnostic test accuracy of blood/plasma/serum BKPyV QNAT and urine BKPyV QNAT for the diagnosis of BKPyVAN after transplantation. We also investigated the following sources of heterogeneity: types and quality of studies, era of publication, various thresholds of BKPyV-DNAemia/BKPyV viruria and variability between assays as secondary objectives.

SEARCH METHODS

We searched MEDLINE (OvidSP), EMBASE (OvidSP), and BIOSIS, and requested a search of the Cochrane Register of diagnostic test accuracy studies from inception to 13 June 2023. We also searched ClinicalTrials.com and the WHO International Clinical Trials Registry Platform for ongoing trials.

SELECTION CRITERIA

We included cross-sectional or cohort studies assessing the diagnostic accuracy of two index tests (blood/plasma/serum BKPyV QNAT or urine BKPyV QNAT) for the diagnosis of BKPyVAN, as verified by the reference standard (histopathology). Both retrospective and prospective cohort studies were included. We did not include case reports and case control studies.

DATA COLLECTION AND ANALYSIS

Two authors independently carried out data extraction from each study. We assessed the methodological quality of the included studies by using Quality Assessment of Diagnostic-Accuracy Studies (QUADAS-2) assessment criteria. We used the bivariate random-effects model to obtain summary estimates of sensitivity and specificity for the QNAT test with one positivity threshold. In cases where meta-analyses were not possible due to the small number of studies available, we detailed the descriptive evidence and used a summative approach. We explored possible sources of heterogeneity by adding covariates to meta-regression models.

MAIN RESULTS

We included 31 relevant studies with a total of 6559 participants in this review. Twenty-six studies included kidney transplant recipients, four studies included kidney and kidney-pancreas transplant recipients, and one study included kidney, kidney-pancreas and kidney-liver transplant recipients. Studies were carried out in South Asia and the Asia-Pacific region (12 studies), North America (9 studies), Europe (8 studies), and South America (2 studies).

INDEX TEST

blood/serum/plasma BKPyV QNAT The diagnostic performance of blood BKPyV QNAT using a common viral load threshold of 10,000 copies/mL was reported in 18 studies (3434 participants). Summary estimates at 10,000 copies/mL as a cut-off indicated that the pooled sensitivity was 0.86 (95% confidence interval (CI) 0.78 to 0.93) while the pooled specificity was 0.95 (95% CI 0.91 to 0.97). A limited number of studies were available to analyse the summary estimates for individual viral load thresholds other than 10,000 copies/mL. Indirect comparison of thresholds of the three different cut-off values of 1000 copies/mL (9 studies), 5000 copies/mL (6 studies), and 10,000 copies/mL (18 studies), the higher cut-off value at 10,000 copies/mL corresponded to higher specificity with lower sensitivity. The summary estimates of indirect comparison of thresholds above 10,000 copies/mL were uncertain, primarily due to a limited number of studies with wide CIs contributed to the analysis. Nonetheless, these indirect comparisons should be interpreted cautiously since differences in study design, patient populations, and methodological variations among the included studies can introduce biases. Analysis of all blood BKPyV QNAT studies, including various blood viral load thresholds (30 studies, 5658 participants, 7 thresholds), indicated that test performance remains robust, pooled sensitivity 0.90 (95% CI 0.85 to 0.94) and specificity 0.93 (95% CI 0.91 to 0.95). In the multiple cut-off model, including the various thresholds generating a single curve, the optimal cut-off was around 2000 copies/mL, sensitivity of 0.89 (95% CI 0.66 to 0.97) and specificity of 0.88 (95% CI 0.80 to 0.93). However, as most of the included studies were retrospective, and not all participants underwent the reference standard tests, this may result in a high risk of selection and verification bias.

INDEX TEST

urine BKPyV QNAT There was insufficient data to thoroughly investigate both accuracy and thresholds of urine BKPyV QNAT resulting in an imprecise estimation of its accuracy based on the available evidence.

AUTHORS' CONCLUSIONS

There is insufficient evidence to suggest the use of urine BKPyV QNAT as the primary screening tool for BKPyVAN. The summary estimates of the test sensitivity and specificity of blood/serum/plasma BKPyV QNAT test at a threshold of 10,000 copies/mL for BKPyVAN were 0.86 (95% CI 0.78 to 0.93) and 0.95 (95% CI 0.91 to 0.97), respectively. The multiple cut-off model showed that the optimal cut-off was around 2000 copies/mL, with test sensitivity of 0.89 (95% CI 0.66 to 0.97) and specificity of 0.88 (95% CI 0.80 to 0.93). While 10,000 copies/mL is the most commonly used cut-off, with good test performance characteristics and supports the current recommendations, it is important to interpret the results with caution because of low-certainty evidence.

Accurate Multiplex qPCR Detection of Epstein-Barr Virus/Cytomegalovirus/BK Virus in Kidney Transplant Patients: Pilot Study

Chronic kidney disease is a really important heath issue, and transplantation is an intervention that can greatly increase patient quality of life and survival. The aim of this study was to perform a comprehensive evaluation of the BK virus, CMV, and EBV in kidney transplant recipients (KTRs); to assess the prevalence of infections; and to test if our detection method would be feasible for use in follow-ups with KTRs. A total of 157 KTRs registered at the Clinical Hospital "Dr. C. I. Parhon", Iași, Romania, were selected using specific inclusion/exclusion criteria. We tested the blood samples from each patient for BK, EBV, and CMV using a multiplex real-time PCR (qPCR) assay and the TaqMan PCR principle. The highest prevalence was detected for BKV (11/157, 7%), followed by CMV (9/157, 5.7%) and EBV (5/157, 3.2%). By simultaneously detecting three possible nephropathic viruses and oncogenes in KTRs using multiplex real-time PCR, we aimed to optimize their monitoring and follow-up. The prevalence of the tested nephropathogenic viruses-BKV, CMV, and EBV-was comparable to that analyzed in other studies. We demonstrate that the use of qPCR for viral detection in KTRs is a robust, cost-effective method for case monitoring.

Challenges and opportunities in research on BK virus infection after renal transplantation

Renal transplantation is one of the primary approaches for curing end-stage kidney disease. With advancements in immunosuppressive agents, the short-term and long-term survival rates of transplanted kidneys have significantly improved. However, infections associated with potent immunosuppression have remained a persistent challenge. Among them, BK virus (BKV) reactivation following renal transplantation leading to BK virus-associated nephropathy (BKVAN) is a major cause of graft dysfunction. However, we still face significant challenges in understanding the pathogenesis, prevention, diagnosis, and treatment of BKVAN. These challenges include: 1. The mechanism of BKV reactivation under immunosuppressive conditions has not been well elucidated, leading to difficulties in breakthroughs in clinical research on prevention, diagnosis, and treatment. 2. Lack of proper identification of high-risk individuals, and effective personalized clinical management strategies. 3.Lack of early and sensitive diagnostic markers. 4. Lack of direct and effective treatment options due to the absence of specific antiviral drugs. The purpose of this review is to summarize the current status and cutting-edge advancements in BKV-related research, providing new methods and perspectives to address future research challenges.

BK Virus Nephropathy After Kidney Transplantation and Its Diagnosis Using Urinary Micro RNA

BK virus-associated nephritis (BKVAN) is an important cause of graft loss in renal transplant recipients B K viremia occurs in up to 30% of renal transplant recipients. Since the discovery of BKV in 1971, effective prophylaxis and treatment have not been established, and it is not uncommon for a transplant kidney to be lost without cure of BKVAN. BK virus infection is reactivated when cellular immunity is suppressed, which is often during the first year after kidney transplantation when cellular immunity is most suppressed. Clinically, it is caused by reactivation of latent infection or new infection from the donor kidney, leading to viremia, viremia, and transplant nephropathy. BK virus nephropathy is currently diagnosed definitively by measuring the amount of BK virus DNA in the blood and proving SV40-positive cells in transplant kidney tissue obtained by transplant kidney biopsy, but the time required for diagnosis and the low sensitivity of immunohistochemistry using antibodies are problematic. Therefore, we investigated whether the diagnosis of BK virus nephropathy could be made earlier by searching for miRNAs in the urine of renal transplant recipients.

BK Polyomavirus DNAemia With a High DNA Load Is Associated With De Novo Donor-Specific HLA Antibodies in Kidney Transplant Recipients

BK polyomavirus-associated nephropathy (BKPyVAN) is a well-known complication of kidney transplantation (KTx). The mainstay of prevention is the reduction of immunosuppression upon detection of BK polyomavirus (BKPyV) DNAemia, which precedes BKPyVAN. However, this reduction may inadvertently increase the risk of alloimmunity particularly in patients with a high BKPyV DNA load, where significant immunosuppression reduction is often necessary. This single-center, retrospective cohort study assesses the risk of de novo donor-specific antibodies (dnDSA) development and biopsy-proven acute rejection (BPAR) following high and low BKPyV DNAemia. All patients who underwent KTx at Leiden University Medical Center between 2011 and 2020 were included. Patients were grouped according to high (maximum BKPyV DNA load > 4log10 copies/mL), low (maximum serum BKPyV DNA load ≤ 10E4 copies/mL), and absent BKPyV DNAemia, and analyzed for the development of dnDSA and BPAR, using Cox regression. Of 1076 KTx recipients included, 108 (10%) developed a BKPyV DNAemia with a maximum DNA load below 4log10 copies/mL, whereas 121 (11.2%) developed a BKPyV DNAemia exceeding 4log10 copies/mL. The risk of dnDSA development was higher in patients with a high BKPyV DNAemia, compared to patients without DNAemia (adjusted hazard ratio of 1.9 (95% CI 1.1-3.2, p = 0.017). No significant difference in dnDSA risk was observed between patients with low and absent BKPyV DNAemia. Risk of BPAR did not differ between groups. Our study shows that higher BKPyV DNA loads in KTx patients are associated with a higher risk for dnDSA development, highlighting the importance of exploring additional strategies for the prevention and treatment of BKPyV infections in KTx recipients.

Advances in virus-specific T-cell therapy for polyomavirus infections: A comprehensive review

Polyomaviruses are a group of small, non-enveloped, double-stranded DNA viruses that can infect various hosts, including humans. BKPyV causes conditions such as human polyomavirus-associated nephropathy (HPyVAN), human polyomavirus-associated haemorrhagic cystitis (HPyVHC), and human polyomavirus-associated urothelial cancer (HPyVUC). JC polyomavirus (JCPyV), on the other hand, is the causative agent of progressive multifocal leukoencephalopathy (PML), a severe demyelinating disease of the central nervous system. PML primarily affects immunocompromised individuals, including those with HIV, recipients of certain immunosuppressive therapies, and transplant patients. The treatment options for HPyV infections have been limited, but recent developments in virus-specific T cell (VST) therapy have shown promise. Although VST therapy has shown potential in treating both BKPyV and JCPyV infections, several challenges remain. These include the time-consuming and costly preparation of VSTs, the need for sophisticated production facilities, and uncertainties regarding the optimal cell type and infusion frequency. To the best of our knowledge, 85 patients with haemorrhagic cystitis, 27 patients with BKPyV viremia, 2 patients with BKPyV nephritis, 14 patients with haemorrhagic cystitis and BKPyV viremia, and 32 patients with PML have been treated with VST in the literature. The overall response results were 82 complete response, 33 partial response, 35 no response, and 10 no-outcome-reported. This review underscores the importance of VST therapy as a promising treatment approach for polyomavirus infections, emphasising the need for continued research and clinical trials to refine and expand this innovative immunotherapeutic strategy.

Transplant Nephrology

The progressive rise in the number of kidney transplant recipients in the last 2 decades is reflective of the technological advances in the field. Nephrologists are responsible for providing long-term longitudinal care to these patients. It is pertinent that nephrologists understand the various nuances of aspects such as immunosuppression, opportunistic infections, and identification of causes associated with graft dysfunction.

Torque Teno Virus Loads as a Marker of Immunosuppression in Pediatric Kidney Transplant Recipients

BACKGROUND

Long-term renal function and survival after kidney transplantation rely on appropriate immunosuppressive treatment to prevent the risk of rejection. New biomarkers are needed to accurately assess the degree of immunosuppression in renal transplant recipients in order to avoid organ rejection and the development of opportunistic infections. Highly prevalent in humans, torque teno virus (TTV), which belongs to the family Anelloviridae, is a small, nonenveloped, single-stranded DNA virus which has not been linked with any specific human illness, but which constitutes a major component of the human virome. Host antiviral responses allow TTV levels to be controlled; however, viral persistence remains, explaining the high prevalence in human populations, including healthy individuals. Important confounders of TTV load include time since transplantation, age, gender, obesity, and smoking status.

AIMS

TTV-based guidance of immunosuppressive drug dosing could help with risk stratification, reducing the risk of infection, graft rejection and oncologic disease on an individual level, enabling long-term patient and graft survival.

METHODS

Original studies were accessed by a systematic search from electronic databases including PubMed, ScienceDirect and Wiley Online Library.

RESULTS

The presented data mainly derive from adult transplant recipients showing an association between TTV plasma levels and the immune status of the host: High-TTV load and high immunosuppression are associated with a risk of infection, and low-TTV load and low immunosuppression indicate a risk of rejection. However, there is minimal information on pediatric transplant recipients with further research required in this cohort. To date, it has been demonstrated that longer posttransplant times are significantly associated with lower TTV levels in children with renal transplant. Meanwhile, an association between lower TTV loads and increased risk of graft reject during the first year of transplantation was also reported. More recently, Eibensteiner et al. revealed a robust, independent association between TTV plasma load and the onset of Cytomegalovirus and BK virus infections.

CONCLUSION

Data from randomized controlled trials are still missing, even in adults, but a multicenter randomized controlled trial for TTV-guided immunosuppression in adult kidney recipients (TTVguideIT) began in 2022. There is, therefore, great promise for TTV levels to be used as a biomarker that could potentially improve both graft and patient survival in transplantation.

Performance of a Global Functional Assay Based on Interferon-γ Release to Predict Infectious Complications and Cancer After Kidney Transplantation

The QuantiFERON-Monitor assay (QTF-Monitor) is intended to assess innate and adaptive immune responses by quantifying interferon (IFN)-γ release upon whole blood stimulation with a TLR7/8 agonist and an anti-CD3 antibody. We performed the QTF-Monitor in 126 kidney transplant recipients (KTRs) at different points during the first 6 post-transplant months. The primary outcome was overall infection, whereas secondary outcomes included bacterial infection, opportunistic infection and de novo cancer. The association between IFN-γ production and outcomes was analyzed as "low" immune responses (<15 IU/mL) and as a continuous variable to explore alternative thresholds. There were no significant differences in the occurrence of overall infection according to the QTF-Monitor at any monitoring point. Regarding secondary outcomes, KTRs with a low response at week 2 experienced a higher incidence of bacterial infection (50.8% versus 24.4%; P-value = 0.006). Low response at month 1 was also associated with opportunistic infection (31.6% versus 14.3%; P-value = 0.033). The discriminative capacity of IFN-γ levels was poor (areas under the ROC curve: 0.677 and 0.659, respectively). No differences were observed for the remaining points or post-transplant cancer. In conclusion, the QTF-Monitor may have a role to predict bacterial and opportunistic infection in KTRs when performed early after transplantation.

Successful prevention of BK-polyomavirus nephropathy using extracorporeal photopheresis for immunosuppression minimisation following severe BK polyomavirus replication after kidney transplantation in a double lung transplant recipient, a case report

BACKGROUND

BK-polyomavirus (BKpyV) nephropathy (BKVN) is associated with end-stage kidney disease in kidney and non-kidney solid organ transplantation, with no curative treatment.

CASE PRESENTATION

A 45-year-old woman with a past medical history of double lung transplantation subsequently developed end-stage kidney disease, of undetermined origin. One month after receiving a kidney transplant, a diagnosis of early BKVN was suspected, and in retrospect was a reasonable cause for the loss of her native kidneys. Minimisation of immunosuppression, achieved through extracorporeal photopheresis, allowed clearance of BKpyV and so prevented nephropathy. Both lung and kidney grafts had a satisfactory and stable function after one year of follow-up, with no rejection.

CONCLUSIONS

Extracorporeal photopheresis may have facilitated minimisation of immunosuppression and BKpyV clearance without lung allograft rejection.

Unusual late presentation of cryptococcal meningitis with simultaneous CMV antigenemia in a kidney transplant recipient

Cryptococcosis is the third most common invasive fungal infection in solid-organ transplant (SOT) recipients after candidiasis and aspergillosis. These patients are at risk of disseminated cryptococcosis because of immuosuppressive therapy. The median time to disease onset after kidney transplantation is approximately 35 months and it rarely occurs more than 10 years after transplantation. Herein, we report a case of 64-year-old kidney transplant recipient suffering from coexisting disseminated cryptococcosis with brain and skin involvement, together with cytomegalovirus (CMV) antigenemia more than 20 years after transplant. She presented with frontal headache and bilateral hand tremor, in addition to multiple nodular lesions over bilateral lower limbs. The diagnosis was made after lumbar puncture and skin biopsy. She was successfully treated with a course of anti-fungal and anti-CMV regimen without any relapse of central nervous system infection. Our case illustrates that disseminated cryptococcosis can occur very late after organ transplant. It is thus important to watch out for late-onset opportunistic infections and strike the balance between risks of infections and rejections in SOT patients.

Risk of cellular or antibody-mediated rejection in pediatric kidney transplant recipients with BK polyomavirus replication-an international CERTAIN registry study

BACKGROUND

In kidney transplant recipients (KTR), BK polyomavirus-associated nephropathy (BKPyVAN) is a major cause of graft loss. To facilitate the clearance of BKPyV-DNAemia, reduction of immunosuppression is currently the treatment of choice but may increase the risk of graft rejection.

METHODS

This international CERTAIN study was designed to determine the risk of alloimmune response and graft dysfunction associated with immunosuppression reduction for BKPyV treatment in 195 pediatric KTR.

RESULTS

BKPyV-DNAemia was associated with a more than twofold increased risk of late T cell-mediated rejection (TCMR) (HR 2.22, p = 0.024), of de novo donor-specific HLA antibodies (dnDSA) and/or antibody-mediated rejection (ABMR) (HR 2.64, p = 0.002), and of graft function deterioration (HR 2.73, p = 0.001). Additional independent risk factors for dnDSA/ABMR development were a higher HLA mismatch (HR 2.72, p = 0.006) and re-transplantation (HR 6.40, p = 0.000). Other independent predictors of graft function deterioration were TCMR (HR 3.98, p = 0.003), higher donor age (HR 1.03, p = 0.020), and re-transplantation (HR 3.56, p = 0.013).

CONCLUSIONS

These data indicate that reduction of immunosuppression for BKPyV-DNAemia management is associated with increased alloimmune response in pediatric KTR. Therefore, regular dnDSA screening and close monitoring of graft function in case of BKPyV-DNAemia followed by subsequent reduction of immunosuppressive therapy are recommended.

Interventions for BK virus infection in kidney transplant recipients

BACKGROUND

BK virus-associated nephropathy (BKVAN), caused by infection with or reactivation of BK virus, remains a challenge in kidney transplantation. Screening is recommended for all kidney transplant recipients. For those with clinically significant infection, reduction of immunosuppression is the cornerstone of management. There is no specific antiviral or immunomodulatory therapy sufficiently effective for routine use.

OBJECTIVES

This review aimed to examine the benefits and harms of interventions for BK virus infection in kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 5 September 2024 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

All randomised controlled trials (RCTs) and cohort studies investigating any intervention for the treatment or prevention of BKVAN for kidney transplant recipients.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the study quality and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Twelve RCTs (2669 randomised participants) were included. Six studies were undertaken in single centres, and six were multicentre studies; two of these were international studies. The ages of those participating ranged from 44 to 57 years. The length of follow-up ranged from three months to five years. All studies included people with a kidney transplant, and three studies included people with signs of BK viraemia. Studies were heterogeneous in terms of the type of interventions and outcomes assessed. The overall risk of bias was low or unclear. Intensive screening for the early detection of BK viraemia or BK viruria prevents graft loss (1 study, 908 participants: RR 0.00, 95% CI 0.00 to 0.05) and decreases the presence of decoy cells and viraemia at 12 months (1 study, 908 participants: RR 0.06, 95% CI 0.03 to 0.11) compared to routine care (high certainty evidence). No other outcomes were reported. Compared to placebo, fluoroquinolones may slightly reduce the risk of graft loss (3 studies, 393 participants: RR 0.37, CI 0.09 to 1.57; I2 = 0%; low certainty evidence), probably makes little or no difference to donor-specific antibodies (DSA), may make little or no difference to BK viraemia and death, had uncertain effects on BKVAN and malignancy, but may increase the risk of tendonitis (2 studies, 193 participants: RR 5.66, CI 1.02 to 31.32; I2 = 0%; low certainty evidence). Compared to tacrolimus (TAC), cyclosporin (CSA) probably makes little or no difference to graft loss and death, may make little or no difference to BKVAN and malignancy, but probably decreases BK viraemia (2 studies, 263 participants: RR 0.61, 95% CI 0.26 to 1.41; I2 = 38%) and probably reduces the risk of new-onset diabetes after transplantation (1 study, 200 participants: RR 0.41, 95% CI 0.12 to 1.35) (both moderate certainty evidence). Compared to azathioprine, mycophenolate mofetil (MMF) probably makes little or no difference to graft loss and BK viraemia but probably reduces the risk of death (1 study, 133 participants: RR 0.43, 95% CI 0.16 to 1.16) and malignancy (1 study, 199 participants: RR 0.43, 95% CI 0.16 to 1.16) (both moderate certainty evidence). Compared to mycophenolate sodium (MPS), CSA has uncertain effects on graft loss and death, may make little or no difference to BK viraemia, but may reduce BKVAN (1 study, 224 participants: RR 0.06, 95% CI 0.00 to 1.20; low certainty evidence). Compared to immunosuppression dose reduction, MMF or TAC conversion to everolimus or sirolimus may make little or no difference to graft loss, BK viraemia or BKVAN (low certainty evidence). TAC conversion to sirolimus probably results in more people having a reduced BK viral load (< 600 copies/mL) than immunosuppression reduction (1 study, 30 participants: RR 1.31, 95% CI 0.90 to 1.89; moderate certainty evidence). Compared to MPS, everolimus had uncertain effects on graft loss and BK viraemia, may reduce BKVAN (1 study, 135 participants: 0.06, 95% CI 0.00 to 1.11) and may increase the risk of death (1 study, 135 participants: RR 3.71, 95% CI 0.20 to 67.35) (both low certainty evidence). Compared to CSA, everolimus may make little or no difference to BK viraemia, has uncertain effects on graft loss and BKVAN, but may increase the risk of death (1 study, 185 participants: RR 3.71, 95% CI 0.42 to 32.55; low certainty evidence). Compared to immunosuppression reduction, the leflunomide derivative FK778 may make little or no difference to graft loss, probably results in a greater reduction in plasma BK viral load (1 study, 44 participants: -0.60 copies/µL, 95% CI -1.22 to 0.02; moderate certainty evidence), but had uncertain effects on BKVAN and malignancy. Aggravated hypertension may be increased with KF778 (1 study, 46 participants: RR 8.23, 95% CI 0.50 to 135.40; low certainty evidence). There were no deaths in either group.

AUTHORS' CONCLUSIONS

Intense monitoring early after transplantation for BK viruria and BK viraemia is effective in improving BK virus infection outcomes as it helps with early detection of the infection and allows for a timely reduction in immunosuppression reduction. There is insufficient evidence to support any other intervention for BK virus infection in kidney transplant recipients.

Belatacept-based immunosuppression does not confer increased risk of BK polyomavirus-DNAemia relative to tacrolimus-based immunosuppression

BACKGROUND

The effect of belatacept on BK polyomavirus (BKPyV) control remains largely unknown.

METHODS

This is a propensity matched retrospective cohort study in adult kidney transplant recipients (KTR) transplanted between 2016-2020 who received a belatacept- versus tacrolimus-based immunosuppression regimen. A continuous time multi-state Markov model was used to evaluate BKPyV replication dynamics (BKPyV-dyn). Three BKPyV-dyn states were defined: BKPyV-dyn1 (viral load <3 log10), BKPyV-dyn2 (viral load ≥ 3 log10 and ≤4 log10), and BKPyV-dyn3 (viral load >4 log10).

RESULTS

Two hundred eighty KTR on belatacept- and 280 KTR on tacrolimus-based regimens were compared. The probability of transitioning between BKPyV-dyn states and time spent in each state in both groups was comparable. Total duration in BKPyV-dyn-1 was 632.1 days (95% CI 612.1, 648.5) for belatacept versus 615.2 days (95% CI 592.5, 635.8) for tacrolimus, BKPyV-dyn-2 was 49.2 days (95% CI 41.3, 58.4) for belatacept versus 55.6 days (95% CI 46.5, 66.8) for tacrolimus, and BKPyV-dyn-3 was 48.7 days (95% CI 37.1, 363.1) for belatacept versus 59.2 days (95% CI 45.8, 73.5) for tacrolimus. BKPyV associated nephropathy (PyVAN) occurred in 3.9% in belatacept- and 3.9% tacrolimus-treated KRT (P > .9).

CONCLUSIONS

Compared with tacrolimus-based immunosuppression, belatacept based immunosuppression was not associated with increased risk of BKPyV-DNAemia or nephropathy.

Imlifidase in Highly Sensitized Kidney Transplant Recipients With a Positive Crossmatch Against a Deceased Donor

Introduction

Imlifidase is authorized for desensitization of highly sensitized adult kidney transplant candidates with a positive crossmatch (XM) against a deceased donor. Here, we report on the results for the first 9 patients transplanted in this context who had at least 3 months of follow-up.

Methods

The eligibility criteria were as follows: calculated panel reactive antibodies (cPRA) ³ 98%, ³ 3 years on the waiting list, immunodominant donor-specific antibodies (DSAs) with mean fluorescence intensity (MFI) > 6000 (and < 5000 at 1:10 dilution) and a negative post-imlifidase complement-dependent cytotoxic XM (CDCXM).

Results

All 9 patients had been on dialysis for an average of 123 ± 41 months, with cPRA at 99% (n = 2) or 100% (n = 7). At transplantation, the mean number of DSAs was 4.3 ± 1.4. The median immunodominant DSA MFI was 9153 (6430-16,980). Flow cytometry XM (FCXM) and CDCXM before imlifidase were positive in 9 and 2 patients, respectively. After 1 injection of imlifidase, all were negative. Patients received polyclonal antibodies, i.v. Igs (IVIg), rituximab, tacrolimus, and mycophenolate. Five patients had a DSA rebound within the first 14 days: 2 had concomitant clinical antibody-mediated rejection (ABMR), 2 had subclinical ABMR, and 1 had isolated positive C4d staining. No ABMR was observed in patients without rebound. Chronic Kidney Disease-Epidemiology Collaboration formula estimated glomerular filtration rate (eGFR) was 56 ± 22 ml/min per 1.73 m2 at the last follow-up (7 ± 2.8 months). No graft loss or death were observed. Four patients developed at least 1 infection.

Conclusion

These real-life data demonstrate that the use of imlifidase to desensitize highly sensitized patients can have an acceptable short-term efficacy and safety profile in selected patients.

Protocol biopsy of kidney allograft enables early detection of BK virus nephropathy to preserve kidney allograft function

BACKGROUND

The Banff Working Group has updated the histological classification of BK virus nephropathy (BKVN), highlighting the importance of early detection. However, an early detection strategy for BKVN using biopsy has not yet been established. Our investigation aimed to assess the efficacy of protocol biopsy for the diagnosis of BKVN.

METHODS

We performed a retrospective cohort study of 314 patients who had undergone kidney transplantation between 2006 and 2021. Kidney allograft biopsies were performed as part of a protocol biopsy at 3 months and 1 year post-transplantation. Following the diagnosis of BKVN, the immunosuppressant dose was reduced.

RESULTS

Twelve patients (3.8%) were diagnosed with BKVN by biopsy. Most diagnoses are established during the early stages of BKVN (polyomavirus nephropathy class 1 in six, class 2 in five, and class 3 in one). Following the reduction in immunosuppressant dose, kidney allograft function did not deteriorate in any patients. Additionally, test for BK virus DNA in the blood was negative. All but one patient demonstrated histological resolution of BKVN, and the other had a very slight positivity for the simian virus 40 large T antigen. The median follow-up time after BKVN diagnosis was 6 years. One patient developed de novo donor-specific antibody and subclinical acute antibody-mediated rejection that was successfully cured.

CONCLUSIONS

Our analysis indicates that protocol biopsy may enable the early detection of BKVN, resulting in the preservation of kidney function.

Peritubular and Tubulointerstitial Inflammation as Predictors of Impaired Viral Clearance in Polyomavirus Nephropathy

Introduction: Polyomavirus-associated nephropathy (BKPyVAN) is a common complication in kidney transplant recipients. The histological changes in the context of BKPyVAN and their association with the viral load and outcomes are still being investigated. Methods: This retrospective study involved 100 adult patients transplanted between 2000 and 2021, with available archived biopsy slides, aiming to analyze associations between viral load clearance in the blood (reduction in BKPyVAN-DNAemia below detection level) and histological features in biopsy-proven BKPyVAN. A kidney pathologist blinded to the clinical data reassessed the BANFF 2019 lesion scores in the BKPyVAN index biopsy. The primary endpoint was viral clearance three months after the diagnosis. Results: The presence of tubulointerstitial inflammation, peritubular capillaritis, and higher PVN Class at the diagnosis was linked to a reduced likelihood of viral clearance three months later (interstitial inflammation OR = 0.2, 95% CI [0.07-0.55], tubulitis OR = 0.39, 95% CI [0.21-0.73], peritubular capillaritis OR = 0.25, 95% CI [0.08-0.82], PVN Score OR = 0.1, 95% CI [0.03-0.4]), independently of other covariates. Combining the four lesions using the ROC analysis enhanced their capability to predict persistent BK viremia after 3 months with an AUC of 0.94. Conclusions: The presence of interstitial inflammation, tubulitis, and peritubular capillaritis, as well as the higher PVN Score, was associated with an up to 90% lower likelihood of viral load clearance three months post-diagnosis. These findings underscore the importance of histological evaluation as a surrogate of subsequent viral clearance and offer valuable insights for the management of BKPyVAN.

Application of graft-derived cell-free DNA for solid organ transplantation

Monitoring the status of grafts and the occurrence of postoperative complications, such as rejection, is crucial for ensuring the success and long-term survival of organ transplants. Traditional histopathological examination, though effective, is an invasive procedure and poses risks of complications, making frequent use impractical. In recent years, graft-derived cell-free DNA (gd-cfDNA) has emerged as a promising non-invasive biomarker. It not only provides early warnings of rejection and other types of graft injury but also offers important information about the effectiveness of immunosuppressive therapy and prognosis. gd-cfDNA shows potential in the monitoring of organ transplants. The early, real-time information on graft injury provided by gd-cfDNA facilitates timely individualized treatment and improves patient outcomes. However, the progress of research on gd-cfDNA varies across different organs. Therefore, this article will comprehensively review the application and findings of gd-cfDNA in monitoring various solid organs, discussing the advantages, limitations, and some future research directions to aid in its clinical application.

Virus-specific T cell therapy to treat refractory viral infections in solid organ transplant recipients

Solid organ transplant recipients require ongoing immunosuppression to prevent acute rejection, which puts them at risk of opportunistic infections. Viral infections are particularly challenging to prevent and treat as many establish latency and thus cannot be eliminated, whereas targets for small molecule antiviral medications are limited. Resistance to antivirals and unacceptable toxicity also complicate treatment. Virus-specific T cell therapies aim to restore host-specific immunity to opportunistic viruses that is lacking due to ongoing immunosuppressive therapy. This minireview will provide a state-of-the-art update of the current virus-specific T cell pipeline and translational research that is likely to lead to further treatment options for viral infections in solid organ transplant recipients.

Third-party virus-specific T cells for the treatment of double-stranded DNA viral reactivation and posttransplant lymphoproliferative disease after solid organ transplant

Reactivation or primary infection with double-stranded DNA viruses is common in recipients of solid organ transplants (SOTs) and is associated with significant morbidity and mortality. Treatment with conventional antiviral medications is limited by toxicities, resistance, and a lack of effective options for adenovirus (ADV) and BK polyomavirus (BKPyV). Virus-specific T cells (VSTs) have been shown to be an effective treatment for infections with ADV, BKPyV, cytomegalovirus (CMV), and Epstein-Barr virus (EBV). Most of these studies have been conducted in stem cell recipients, and no large studies have been published in the SOT population to date. In this study, we report on the outcome of quadrivalent third-party VST infusions in 98 recipients of SOTs in the context of an open-label phase 2 trial. The 98 patients received a total of 181 infusions, with a median of 2 infusions per patient. The overall response rate was 45% for BKPyV, 65% for cytomegalovirus, 68% for ADV, and 61% for Epstein-Barr virus. Twenty percent of patients with posttransplant lymphoproliferative disorder had a complete response and 40% of patients had a partial response. All the VST infusions were well tolerated. We conclude that VSTs are safe and effective in the treatment of viral infections in SOT recipients.

The Second International Consensus Guidelines on the Management of BK Polyomavirus in Kidney Transplantation

BK polyomavirus (BKPyV) remains a significant challenge after kidney transplantation. International experts reviewed current evidence and updated recommendations according to Grading of Recommendations, Assessment, Development, and Evaluations (GRADE). Risk factors for BKPyV-DNAemia and biopsy-proven BKPyV-nephropathy include recipient older age, male sex, donor BKPyV-viruria, BKPyV-seropositive donor/-seronegative recipient, tacrolimus, acute rejection, and higher steroid exposure. To facilitate early intervention with limited allograft damage, all kidney transplant recipients should be screened monthly for plasma BKPyV-DNAemia loads until month 9, then every 3 mo until 2 y posttransplant (3 y for children). In resource-limited settings, urine cytology screening at similar time points can exclude BKPyV-nephropathy, and testing for plasma BKPyV-DNAemia when decoy cells are detectable. For patients with BKPyV-DNAemia loads persisting >1000 copies/mL, or exceeding 10 000 copies/mL (or equivalent), or with biopsy-proven BKPyV-nephropathy, immunosuppression should be reduced according to predefined steps targeting antiproliferative drugs, calcineurin inhibitors, or both. In adults without graft dysfunction, kidney allograft biopsy is not required unless the immunological risk is high. For children with persisting BKPyV-DNAemia, allograft biopsy may be considered even without graft dysfunction. Allograft biopsies should be interpreted in the context of all clinical and laboratory findings, including plasma BKPyV-DNAemia. Immunohistochemistry is preferred for diagnosing biopsy-proven BKPyV-nephropathy. Routine screening using the proposed strategies is cost-effective, improves clinical outcomes and quality of life. Kidney retransplantation subsequent to BKPyV-nephropathy is feasible in otherwise eligible recipients if BKPyV-DNAemia is undetectable; routine graft nephrectomy is not recommended. Current studies do not support the usage of leflunomide, cidofovir, quinolones, or IVIGs. Patients considered for experimental treatments (antivirals, vaccines, neutralizing antibodies, and adoptive T cells) should be enrolled in clinical trials.

Comparative performance evaluation of random access and real-time PCR techniques in the diagnosis of BK virus infections in transplant patients

PURPOSE

The study aims to compare random-access NeuMoDx values with artus qPCR values to validate the accuracy of NeuMoDx as an alternative to qPCR and provide an equation to convert copies/ml to IU/ml measurements.

METHODS

A total of 95 samples, including 61 transplant patient samples (n = 23 urine, n = 38 plasma) as the study group, 28 BKPyV-free samples as the control group, and six quality control samples, were included. One-Way ANOVA, Pearson correlation, Bland-Altman, Passing-Bablok, Deming regression analyses were used for statistical evaluation.

RESULTS

Of 95 samples, 46 (48 %) were positive with NeuMoDx, while 40 (42 %) were positive with artus qPCR. Both techniques were statistically similar (p > 0.05). Deming correlation analysis (r = 0.9590), Passing Bablok and Bland Altman analyses demonstrated a strong correlation between NeuMoDx and artus values. The equation that provides the conversion between NeuMoDx and artus qPCR values was NeuMoDx= (1.12965 x artus qPCR) - 0.55016. BKPyV infections remain a concern for transplant patients globally, and effective new diagnostic methods are required.

CONCLUSIONS

Consistency between the results of NeuMoDx and qPCR confirms that NeuMoDx may be a valuable alternative for detecting BKPyV to prevent viral propagation. Our findings may allow converting copy/ml results to IU/ml for diagnosing and monitoring BKPyV infections in transplant patients.

Approach to Kidney Allograft Dysfunction: A Brief Review

It is important for providers caring for kidney transplant recipients to be familiar with the common causes of allograft dysfunction. Early detection of allograft dysfunction leads to timely management, with the goal of preventing or delaying progression to allograft failure. Although transplant rejection is always a concern, the differential diagnoses for allograft dysfunction are broad and include perioperative complications, infections, recurrent disease, and calcineurin nephrotoxicity. In this review, we will go over early and late causes of allograft dysfunction and discuss the basic workup and principles of management for each condition.

Performance of the cobas EBV and cobas BKV assays: multi-site comparison of standardized quantitation

Guidelines recommend monitoring of Epstein-Barr virus (EBV) and BK virus (BKV) in solid organ and hematopoietic stem cell transplant patients. The majority of quantitative DNA testing for EBV and BKV employs unstandardized individual laboratory-developed testing solutions (LDTs), with implications for accuracy, reproducibility, and comparability between laboratories. The performance of the cobas EBV and cobas BKV assays was assessed across five laboratories, using the World Health Organization International Standards (WHO IS) for EBV and BKV, and the National Institute of Standards and Technology Quantitative Standard for BKV, and results were compared with the LDTs in use at the time. Methods were also compared using locally sourced clinical specimens. Variation was high when laboratories reported EBV or BKV DNA values using LDTs, where quantitative values were observed to differ by up to 1.5 log10 unit/mL between sites. Conversely, results from the cobas EBV and cobas BKV assays were accurate and reproducible across sites and on different testing days. Adjustment of LDTs using the international standards led to closer alignment between the assays; however, day-to-day reproducibility of LDTs remained high. In addition, BKV continued to show bias, indicating challenges with the commutability of the BKV International Standard. The cobas EBV and cobas BKV assays are automated, aligned to the WHO IS, and have the potential to reduce the variability in viral load testing introduced by differences in LDTs. Standardization of reporting values may eventually allow different centers to compare data to allow clinical decision thresholds to be established supporting improvements in patient management.IMPORTANCEThe application of center-specific cut-offs for clinical decisions and the variability of LDTs often hinder interpretation; thus, the findings reported here support the need for standardization in the field of post-transplant monitoring of EBV and BKV to improve patient management. Alongside the choice of assay, it is also important to consider which standard to use when deciding upon a testing methodology. This is a call to action for standardization, as treatment for EBV and BKV is driven by viral load test results, and the more accurate and comparable the test results are across institutions, the more informed and better the treatment decisions can be.

Allogeneic CD4 T Cells Sustain Effective BK Polyomavirus-Specific CD8 T Cell Response in Kidney Transplant Recipients

Introduction

BK polyomavirus-associated nephropathy (BKPyVAN) is a significant complication in kidney transplant recipients (KTRs), associated with a higher level of plasmatic BK polyomavirus (BKPyV) replication and leading to poor graft survival.

Methods

We prospectively followed-up with 100 KTRs with various degrees of BKPyV reactivation (no BKPyV reactivation, BKPyV-DNAuria, BKPyV-DNAemia, and biopsy-proven BKPyVAN [bp-BKPyVAN], 25 patients per group) and evaluated BKPyV-specific T cell functionality and phenotype.

Results

We demonstrate that bp-BKPyVAN is associated with a loss of BKPyV-specific T cell proliferation, cytokine secretion, and cytotoxic capacities. This severe functional impairment is associated with an overexpression of lymphocyte inhibitory receptors (programmed cell death 1 [PD1], cytotoxic T lymphocyte-associated protein 4, T cell immunoreceptor with Ig and ITIM domains, and T cell immunoglobulin and mucin domain-containing-3), highlighting an exhausted-like phenotype of BKPyV-specific CD4 and CD8 T cells in bp-BKPyVAN. This T cell dysfunction is associated with low class II donor-recipient human leukocyte antigen (HLA) divergence. In contrast, in the context of higher class II donor-recipient HLA (D/R-HLA) divergence, allogeneic CD4 T cells can provide help that sustains BKPyV-specific CD8 T cell responses. In vitro, allogeneic HLA-mismatched CD4 T cells rescue BKPyV-specific CD8 T cell responses.

Conclusion

Our findings suggest that in KTRs, allogeneic CD4 T cells can help to maintain an effective BKPyV-specific CD8 T cell response that better controls BKPyV replication in the kidney allograft and may protect against BKPyVAN.

BK polyomavirus DNAemia, allograft rejection, and de novo donor-specific antibodies after lowering target tacrolimus levels in pediatric kidney transplant recipients

BACKGROUND

BK polyomavirus (BKV) DNAemia is a challenging infectious complication after kidney transplant (KT). Reduction of immunosuppression is the mainstay of management, and tacrolimus is often the first immunosuppressive medication adjusted upon the diagnosis of BKV DNAemia. This study aimed to evaluate the impact of a new institutional protocol with lower target tacrolimus levels on BKV DNAemia, allograft rejection, and de novo donor-specific antibodies (dnDSA) among pediatric KT recipients.

METHODS

We conducted a retrospective chart review of all KT episodes between January 2013 and December 2018. The new protocol with lower target tacrolimus levels was implemented in March 2015. One hundred twenty-seven patients were included in primary analysis. All patients received induction with basiliximab and methylprednisolone and were maintained on a steroid-based immunosuppressive regimen.

RESULTS

In the post-intervention cohort, cumulative incidence of BKV DNAemia at 100 days (13.4% vs. 17.8%, p = .605) and 18 months post-KT (34.1% vs. 26.7%, p = .504) was not significantly different from the pre-intervention cohort. Biopsy-proven rejection rate did not change. However, we observed a trend toward earlier development of dnDSA in the post-intervention cohort using the Kaplan-Meier survival analysis (log-rank p = .06). Younger recipient age at the time of transplant was found to slightly increase the risk of BKV DNAemia (OR: 1.09, 95% CI [1.01, 1.16], p = .024). There was an association between BKV DNAemia and biopsy-proven rejection of any type (adjustedOR: 2.77, 95% CI [1.26, 6.23], p = .012), especially acute T-cell-mediated rejection grade 1A and above (adjustedOR: 2.95, 95% CI [1.06, 8.30], p = .037), after adjusted for recipient age at the time of transplant.

CONCLUSIONS

Targeting lower tacrolimus levels did not decrease the incidence of BKV DNAemia within 100 days or 18 months post-KT, nor did it increase the risk of biopsy-proven rejection among pediatric KT recipients in our center. However, there was a trend toward earlier development of dnDSA, which may portend worse long-term graft outcome post-KT. Our findings highlight the need for individualized immunosuppressive regimens based on immunologic and infectious risk factors and the importance of implementing innovative biomarkers to guide therapy and improve outcomes.

Concurrent JCPyV-DNAemia Is Correlated With Poor Graft Outcome in Kidney Transplant Recipients With Polyomavirus-associated Nephropathy

BACKGROUND

Co-infection of JC polyomavirus (JCPyV) and BK polyomavirus (BKPyV) is uncommon in kidney transplant recipients, and the prognosis is unclear. This study aimed to investigate the effect of concurrent JCPyV-DNAemia on graft outcomes in BKPyV-infected kidney transplant recipients with polyomavirus-associated nephropathy (PyVAN).

METHODS

A total of 140 kidney transplant recipients with BKPyV replication and PyVAN, 122 without concurrent JCPyV-DNAemia and 18 with JCPyV-DNAemia were included in the analysis. Least absolute shrinkage and selection operator regression analysis and multivariate Cox regression analysis were used to identify prognostic factors for graft survival. A nomogram for predicting graft survival was created and evaluated.

RESULTS

The median tubulitis score in the JCPyV-DNAemia-positive group was higher than in JCPyV-DNAemia-negative group ( P  = 0.048). At last follow-up, the graft loss rate in the JCPyV-DNAemia-positive group was higher than in the JCPyV-DNAemia-negative group (50% versus 25.4%; P  = 0.031). Kaplan-Meier analysis showed that the graft survival rate in the JCPyV-DNAemia-positive group was lower than in the JCPyV-DNAemia-negative group ( P  = 0.003). Least absolute shrinkage and selection operator regression and multivariate Cox regression analysis demonstrated that concurrent JCPyV-DNAemia was an independent risk factor for graft survival (hazard ratio = 4.808; 95% confidence interval: 2.096-11.03; P  < 0.001). The nomogram displayed favorable discrimination (C-index = 0.839), concordance, and clinical applicability in predicting graft survival.

CONCLUSIONS

Concurrent JCPyV-DNAemia is associated with a worse graft outcome in BKPyV-infected kidney transplant recipients with PyVAN.

Therapeutic Myths in Solid Organ Transplantation Infectious Diseases

Infection management in solid organ transplantation poses unique challenges, with a diverse array of potential pathogens and associated antimicrobial therapies. With limited high-quality randomized clinical trials to direct optimal care, therapeutic "myths" may propagate and contribute to suboptimal or excessive antimicrobial use. We discuss 6 therapeutic myths with particular relevance to solid organ transplantation and provide recommendations for infectious diseases clinicians involved in the care of this high-risk population.

Polyomavirus nephropathy: diagnosis, histologic features, and differentiation from acute rejection

Polyomaviruses, particularly BK virus, are ubiquitous latent infections that may reactivate with immunosuppression during kidney transplantation, resulting in polyomavirus nephropathy (PVN). The levels of viruria and viremia serve as tools for screening and making a presumptive diagnosis of PVN, respectively, while a definitive diagnosis requires a kidney biopsy. There are histologic classifications of PVN based on the extent of tubular cell viral infection, interstitial fibrosis, and interstitial inflammation. These classifications correlate to some degree with graft function and loss, aiding in determining treatment efficacy and prognostication. PVN has histologic overlap with acute cell-mediated rejection, making the differential diagnosis challenging, although there are suggestive features for these different causes of graft dysfunction. This article reviews the diagnosis, histologic findings, and classifications of PVN, and discusses how to differentiate viral nephropathy from acute rejection.

A comparative analysis of clinical outcomes between conversion to mTOR inhibitor and calcineurin inhibitor reduction in managing BK viremia among kidney transplant patients

BK virus-associated nephropathy (BKVAN) exerts a substantial impact on allograft survival, however, the absence of robust clinical evidence regarding treatment protocols adds to the complexity of managing this condition. This study aimed to compare the two treatment approaches. The study population consisted of patients who underwent kidney transplantation between January 2016 and June 2020 at two tertiary hospitals in Korea. Patients diagnosed with BK viremia were evaluated based on their initial viral load and the treatment methods. The 'Reduction group' involved dose reduction of tacrolimus while the 'Conversion group' included tacrolimus discontinuation and conversion to sirolimus. A total of 175 patients with an initial viral load (iVL) ≥ 3 on the log10 scale were evaluated within two iVL intervals (3-4 and 4-5). In the iVL 4-5 interval, the Reduction group showed potential effectiveness in terms of viral clearance without statistically significant differences. However, within the iVL 3-4 interval, the Reduction group demonstrated superior viral clearance and a lower incidence of biopsy-proven acute rejection (BPAR) than the Conversion group. The renal function over 12 months after BKV diagnosis showed no statistically significant difference. Reducing tacrolimus compared to converting to mTORi would be a more appropriate treatment approach for BK viral clearance in kidney transplantation. Further research is warranted in a large cohort of patients.

Burden and frequency of viral testing of kidney and non-kidney transplant recipients

Transplant patients are at risk of infections due to long-term immunosuppression contributing to morbidity and mortality in this population. Post-transplant testing guidelines were established to monitor and guide therapeutic interventions in transplant recipients. We hypothesize that there are gaps in adherence to the recommended frequency of laboratory testing in post-transplant patients. We analyzed national reference laboratory data to compare viral post-transplant infection (PTI) testing frequency with their respective published guidelines to understand patient uptake and compliance. We evaluated the ordering patterns, positivity rates, and frequency of molecular infectious disease tests (MIDTs). We included 345 patients with International Classification of Diseases (ICD)-10 codes for transplant (Z940-Z942, Z944, Z9481, Z9483, Z9484) with at least two tests (within 7 days) in January 2019 and at least one test in December 2020 to find patients in the post-transplant period. We analyzed two cohorts: kidney transplant recipients (KTRs; 40%) and non-KTR (60%) then followed them longitudinally for the study period. In KTR cohort, high-to-low proportion of ordered MIDT was blood BK virus (bBKV) followed by cytomegalovirus (CMV); in non-KTR cohort, CMV was followed by Epstein-Barr virus (EBV). KTR cohort positivity was highest for urine BK virus (uBKV; 58%) followed by EBV (46%), bBKV (40%), and CMV (31%). Non-KTR cohort positivity was highest for uBKV (64%), EBV (51%), CMV (30%), bBKV (8%), and adenovirus (7%). All patients were tested at progressively longer intervals from the date of the first post-transplant ICD-10-coded test. More than 40% of the KTR cohort were tested less frequently for EBV and bBKV, and more than 20% of the non-KTR cohort were tested for EBV less frequently than published guidelines 4 months after transplant. Despite regular testing, the results of MIDT testing for KTR and non-KTR patients in the post-transplant period are not aligned with published guidelines.IMPORTANCEGuidance for post-transplant infectious disease testing is established, however, for certain infections it allows for clinician discretion. This leads to transplant center policies developing their own testing/surveillance strategies based on their specific transplant patient population (kidney, stem cell, etc.). The Organ Procurement and Transplant Network (OPTN) has developed a strategic plan to improve and standardize the transplant process in the US to improve outcomes of living donors and recipients. Publishing national reference lab data on the testing frequency and its alignment with the recommended guidelines for post-transplant infectious diseases can inform patient uptake and compliance for these strategic OPTN efforts.

The association of Torque Teno viral load with CMV and BKV infection in pediatric and adolescent kidney transplant patients

BACKGROUND

Long-term allograft and patient survival after kidney transplantation (KTX) depends on the balance between over- and under-immunosuppression (IS). High levels of IS predispose to opportunistic infections. Plasma load of Torque Teno Virus (TTV), a non-pathogenic highly prevalent Annellovirus, is associated with its hosts immune status, especially after solid organ transplantation.

OBJECTIVES

To investigate the association of plasma TTV load and opportunistic viral infections after pediatric KTX.

STUDY DESIGN

This retrospective study includes all pediatric KTX patients followed at the Medical University of Vienna 2014-2020. PCR for Cytomegalovirus (CMV), Epstein-Barr virus (EBV), BK virus (BKV), and TTV was performed every 4-8 weeks at routine follow-up visits.

RESULTS

71 pediatric KTX patients were followed with TTV measurements for a median of 2.7 years. TTV plasma load was associated with CMV DNAemia at the next visit with an OR of 2.37 (95 % CI 1.15-4.87; p = 0.03) after adjustment for time after KTX and recipient age. For a cut-off of 7.68 log10 c/mL TTV a sensitivity of 100 %, a specificity of 61 %, a NPV 100 %, and a PPV of 46 % to detect CMV DNAemia at the next visit was calculated. TTV plasma loads were also associated with BKV DNAuria and BKV DNAemia at the next visit, but not with EBV DNAemia.

CONCLUSIONS

This is the first study to analyse associations between TTV plasma loads and opportunistic viral infections in pediatric KTX. We were able to present a TTV cut-off for the prediction of clinically relevant CMV DNAemia that might be useful in clinical care.

SOHO State of the Art Updates and Next Questions | CTLs for Infections Following Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (AHSCT) is an important modality in the treatment of acute leukemia and other hematologic disorders. The post-transplant period is associated with prolonged periods of impaired immune function. Delayed T-cell immune reconstitution is correlated with increased risk of viral, bacterial, and fungal infections. This risk increases with high intensity inductions regimens often required for alternative donor sources. Current therapies for prophylaxis and treatment of these infections are limited by poor efficacy and significant toxicity. Adoptive cell therapy with cytotoxic T lymphocytes (CTL) has proven to be both efficacious and safe in the management of post-transplant viral infections. Recent advances have led to faster production of CTLs and broadened applications for their use. In particular, the generation of third party CTLs has helped ameliorate the problems related to donor availability and product generation time. In this review we aim to describe both the history of CTL use and current advances in the field.

Molecular epidemiology and risk factors associated with BK and JC polyomavirus urinary shedding after kidney allograft

Polyomaviruses BK (BKPyV) and JC (JCPyV), belonging to the Polyomaviridae, are responsible for human pathologies. In kidney transplant recipients, BKPyV replication can lead to irreversible nephron damage whereas JCPyV replication remains asymptomatic. Concomitant replication is rare and potential competition between the infections has been described. The aim of this retrospective case-control study was to describe the molecular epidemiology and risk factors associated with BKPyV and JCPyV replication in a cohort of kidney transplant recipients. In total, 655 urine samples from 460 patients were tested for BKPyV and JCPyV DNA. Positive samples were submitted to strain genotyping. Demographic and clinical characteristics were also compared. Isolated JCPyV and BKPyV was found in 16.5% and 23.3% of patients, respectively; co-replication was rare (3.9%). BKPyV strains Ib-2, Ib-1, and IVc-2 were the most prevalent. JCPyV strains mostly belonged to genotypes 4 and 1B. During follow-up, JCPyV shedding significantly reduced the risk of BKPyV DNAuria, with an odds ratio of 0.57 (95% confidence interval: 0.35-0.99), and was associated with better prognosis than BKPyV replication, based on the estimated glomerular filtration rate. Molecular epidemiology of BKPyV and JCPyV strains in our region was similar to previous studies. This study suggests that JCPyV is benign and appears to limit damaging BKPyV replication. JCPyV DNAuria screening could thus be a useful strategy to predict BKPyV-related outcomes.

Polyomavirus Nephropathy in ABO Blood Group-Incompatible Kidney Transplantation: Torque Teno Virus and Immunosuppressive Burden as an Approximation to the Problem

Introduction

Earlier reports suggest that patients after ABO-incompatible kidney transplantation (ABOi) are at enhanced risk of developing BK-virus (BKV, also known as BK polyomavirus [BKPyV]) nephropathy (BKPyVAN). It remains elusive whether this is a result of more intense immunosuppression or an ABOi-associated "intrinsic attribute." To address this question, we measured Torque Teno virus (TTV) loads as a quantitative proxy for immunosuppressive depth in ABOi recipients and compared them to human leukocyte antigen-incompatible (HLAi, i.e. pretransplant donor-specific antibody-positive) and standard-risk transplant recipients.

Methods

Our retrospective study screened 2256 consecutive kidney transplantations performed between 2007 and 2020 at the Medical University of Vienna. Out of 629 in-principle eligible transplantations, we were able to include 465 patients: 42 ABOi, 106 HLAi, and 317 control recipients. Longitudinal TTV- polymerase chain reaction (PCR) and BKV-PCR was carried out at predefined timepoints and ranged from pretransplant until month 24 posttransplantation. TTV loads and immunosuppression were evaluated in the context of BKV-associated complications.

Results

ABOi recipients had a higher TTV load compared to HLAi and controls both at month 3 (median 1.5 × 109 vs. 2.4 × 108 vs. 9.1 × 107; P = 0.010) and at month 6 (3.1 × 109 vs. 1.4 × 107 vs. 6.4 × 107; P = 0.014) posttransplantation. Tacrolimus exposure was significantly higher in ABOi patients compared to HLAi and control patients (ABOi vs. HLAi: P = 0.007; ABOi vs. controls: P < 0.0001). Biopsy-proven BKPyVAN was more frequent in ABOi recipients when compared to HLAi and control recipients (11.9% vs. 2.8% vs. 4.1%; P = 0.046).

Conclusion

Our data support the assumption that ABOi patients are indeed at higher risk to develop BKPyVAN. A higher TTV load and immunosuppressive burden suggest that intense immunosuppression, rather than an "intrinsic attribute" conferred by ABOi, may contribute to this finding.

BK Polyomavirus in Pediatric Renal Transplantation-What We Know and What We Do Not

BK polyomavirus (BKPyV) is still a real threat in the management of kidney transplantation. Immunosuppressive treatment disrupts the equilibrium between virus replication and immune response, and uncontrolled BKPyV replication leads to nephropathy (BKPyV nephropathy). The first evidence of BKPyV reactivation in transplant recipients is the detection of viral shedding in urine, which appears in 20% to 60% of patients, followed by BKPyV viremia in 10-20% of kidney transplant recipients. BKPyV nephropathy eventually occurs in 1-10% of this population, mainly within the first 2 years post-transplantation, causing graft loss in about half of those patients. Few data exist regarding the pediatric population and we focus on them. In this paper, we review the existing diagnostic methods and summarize the evidence on the role of BKPyV humoral and cellular immunity in modulating the clinical course of BKPyV infection and as potential predictors of the outcome. We look at the known risk factors for BKPyV nephropathy in the immunosuppressed patient. Finally, we propose a sensible clinical attitude in order to screen and manage BKPyV infection in kidney transplant children.

Urinary Tract Infections in Children

Despite the American Academy of Pediatrics guidelines for the evaluation, treatment, and management of urinary tract infections (UTIs), UTI diagnosis and management remains challenging for clinicians. Challenges with acute UTI management stem from vague presenting signs and symptoms, diagnostic uncertainty, limitations in laboratory testing, and selecting appropriate antibiotic therapy in an era with increasing rates of antibiotic-resistant uropathogens. Recurrent UTI management remains difficult due to an incomplete understanding of the factors contributing to UTI, when to assess a child with repeated infections for kidney and urinary tract anomalies, and limited prevention strategies. To help reduce these uncertainties, this review provides a comprehensive overview of UTI epidemiology, risk factors, diagnosis, treatment, and prevention strategies that may help pediatricians overcome the challenges associated with acute and recurrent UTI management.

Preemptive intravenous human immunoglobulin G suppresses BK polyomavirus replication and spread of infection in vitro

BK polyomavirus (BKPyV) infection causes various diseases in immunocompromised patients. Cells from human lung and kidney were infected with BKPyV and treated with commercially available intravenous immunoglobulin G (IVIG). Its effects on BKPyV replication and spread of infection were investigated, focusing on administration timing. IVIG treatment 3 hours after infection suppressed BKPyV replication assessed by real-time PCR and expression of the viral capsid protein 1 and large T-antigen. IVIG effectively reduced the number of BKPyV-infected cells 2 weeks after infection in an antibody titer-dependent manner. Virus release in the culture supernatants was not influenced by IVIG treatment 6-80 hours and 3-9 days after infection. Collectively, IVIG did not affect viral release from infected cells but inhibited the spread of infection by neutralizing the released virus and blocking the new infected cell formation, indicating greater efficacy in early localized infection. BKPyV replication resumed in IVIG-treated cultures at 7 days after IVIG removal. Early prophylactic administration of IVIG is expected to reduce the growth and spread of BKPyV infection, resulting in the reduction of infected cell lesions and prevention of BKPyV-associated diseases.

Posoleucel in Kidney Transplant Recipients with BK Viremia: Multicenter, Randomized, Double-Blind, Placebo-Controlled Phase 2 Trial

Key Points

Posoleucel was generally safe, well tolerated, and associated with a greater reduction of BK viremia compared with placebo. BK viremia reduction occurred coincident with an increase in the circulating frequency of BK virus–specific T cells in posoleucel recipients. The presence and persistence of posoleucel was confirmed by T-cell receptor variable β sequencing.

Background

Kidney transplant recipients with BK virus infection are at risk of developing BK virus–associated nephropathy, allograft rejection, and subsequent graft loss. There are no approved treatments for BK virus infection. Posoleucel is an off-the-shelf, allogeneic, multivirus-specific T-cell investigational therapy targeting BK virus, as well as five other opportunistic viruses: adenovirus, cytomegalovirus, Epstein–Barr virus, human herpesvirus 6, and John Cunningham virus.

Methods

In this phase 2, double-blind study, kidney transplant recipients with BK viremia were randomized 1:1:1 to receive posoleucel weekly for 3 weeks and then every 14 days (bi-weekly dosing) or every 28 days (monthly dosing) or placebo for 12 weeks. Participants were followed for 12 weeks after completing treatment. The primary objective was safety; the secondary objective was plasma BK viral load reduction.

Results

Sixty-one participants were randomized and dosed. Baseline characteristics were similar across groups. No deaths, graft-versus-host disease, or cytokine release syndrome occurred. The proportion of patients who had adverse events (AEs) judged by the investigators to be treatment-related was slightly lower in recipients of posoleucel: 20% (4 of 20 patients) and 18% (4 of 22) in those infused on a bi-weekly and monthly schedule, respectively, and 26% (5 of 19) in placebo recipients. None of the grade 3–4 AEs or serious AEs in any group were deemed treatment-related. No deaths, graft-versus-host disease, or cytokine release syndrome occurred. Three participants had allograft rejection, but none were deemed treatment-related by investigators. In posoleucel recipients, BK viremia reduction was associated with an increase in the circulating frequency of BK virus–specific T cells, and the presence and persistence of posoleucel was confirmed by T-cell receptor sequencing.

Conclusions

Posoleucel was generally safe, well tolerated, and associated with a larger reduction of BK viremia compared with placebo. Limitations of this study include the relatively short duration of follow-up and lack of power to detect significant differences in clinical outcomes.

Clinical Trial registry name and registration number:

Study of Posoleucel (Formerly Known as ALVR105; Viralym-M) in Kidney Transplant Patients With BK Viremia, NCT04605484 .

Epidemiology and Dynamics of BK Polyomavirus Replication after Kidney Transplantation

BACKGROUND/OBJECTIVES

In the absence of an effective antiviral treatment for BK polyomavirus (BKPyV), a better understanding of the epidemiology and time course of BKPyV replication after kidney transplantation is needed to limit the virus's impact on the graft outcome.

METHODS

In a 7-year study, we screened more than 430 kidney transplant recipients and analyzed the time course and virological characteristics of BKPyV replication.

RESULTS

Urinary viral replication was observed in 116 (27%) of the 430 patients, and 90 of the 116 (78%) had viral DNAemia. Thirty-eight patients (8.8%) were presumed to have nephropathy (DNAemia > 4 log10 copies/mL). Of the patients with BKPyV replication, 48%, 60%, 71%, and 80% were first found to be positive one, two, three, and four months post-transplantation. The initial viral load in the urine was below 7 log10 copies/mL in 100% of the patients with viral replication first detected before the first month, and this proportion was 57% when viral replication was first detected after the first month. When the BKPyV replication was first detected in a urine sample at month 3 or later, 81.5% of patients had concomitant BKPyV DNAemia. The predominant viral subtype was Ib2 (60%), and there was no apparent relationship between the subtype and the time course of BKPyV replication.

CONCLUSIONS

Urinary BKPyV replication occurs early after renal transplantation and in most patients will increase to a level requiring therapeutic intervention. Close monitoring for BKPyV in the early post-transplantation period would enable the pre-emptive adjustment of the immunosuppression regimen.

Performance evaluation of the high-throughput quantitative Alinity m BK virus assay

BK virus (BKV) infection or reactivation in immunocompromised individuals can lead to adverse health consequences including BKV-associated nephropathy (BKVAN) in kidney transplant patients and BKV-associated hemorrhagic cystitis (BKV-HC) in allogeneic hematopoietic stem cell transplant recipients. Monitoring BKV viral load plays an important role in post-transplant patient care. This study evaluates the performance of the Alinity m BKV Investigational Use Only (IUO) assay. The linearity of the Alinity m BKV IUO assay had a correlation coefficient of 1.000 and precision of SD ≤ 0.25 Log IU/mL for all panel members tested (2.0-7.3 Log IU/mL). Detection rate at 50 IU/mL was 100%. Clinical plasma specimens tested comparing Alinity m BKV IUO to ELITech MGB Alert BKV lab-developed test (LDT) on the Abbott m2000 platform using specimen extraction protocols for DNA or total nucleic acid (TNA) resulted in coefficient of correlation of 0.900 and 0.963, respectively, and mean bias of 0.03 and -0.54 Log IU/mL, respectively. Alinity m BKV IUO compared with Altona RealStar BKV and Roche cobas BKV assays demonstrated coefficient of correlation of 0.941 and 0.980, respectively, and mean bias of -0.47 and -0.31 Log IU/mL, respectively. Urine specimens tested on Alintiy m BKV IUO and ELITech BKV LDT using TNA specimen extraction had a coefficient of correlation of 0.917 and mean bias of 0.29 Log IU/mL. The Alinity m BKV IUO assay was performed with high precision across the dynamic range and correlated well with other available BKV assays.

IMPORTANCE

BK virus (BKV) in transplant patients can lead to adverse health consequences. Viral load monitoring is important in post-transplant patient care. This study evaluates the Alinity m BKV assay with currently available assays.