BK Polyomavirus Subtypes II and IV in Hematopoietic Cell Transplant Recipients

Symptomatic BK polyomavirus (BKPyV) infections are common and relevant in immunocompromised patients. Here, we present full-length BKPyV genomes from samples from patients who received hematopoietic cell transplants in the United States. These individuals had non-subtype I BKPyV, as determined by amplification, next-generation sequencing, and phylogenetic analysis.

Clinical Relevance of Absolute BK Polyoma Viral Load Kinetics in Patients With Biopsy Proven BK Polyomavirus Associated Nephropathy

Introduction: The absolute BK viral load is an important diagnostic surrogate for BK polyomavirus associated nephropathy (PyVAN) after renal transplant (KTX) and serial assessment of BK viremia is recommended. However, there is no data indicating which particular viral load change, i.e., absolute vs. relative viral load changes (copies/ml; percentage of the preceding viremia) is associated with worse renal graft outcomes.Materials and Methods: In this retrospective study of 91 biopsy proven PyVAN, we analyzed the interplay of exposure time, absolute and relative viral load kinetics, baseline risk, and treatment strategies as risk factors for graft loss after 2 years using a multivariable Poisson-model.Results: We compared two major treatment strategies: standardized immunosuppression (IS) reduction (n = 53) and leflunomide (n = 30). The median viral load at the index biopsy was 2.15E+04 copies/ml (interquartile range [IQR] 1.70E+03–1.77E+05) and median peak viremia was 3.6E+04 copies/ml (IQR 2.7E+03–3.3E+05). Treatment strategies and IS-levels were not related to graft loss. After correction for baseline viral load and estimated glomerular filtration rate (eGFR), absolute viral load decrease/unit remained an independent risk factor for graft loss [incidence rate ratios [IRR] = 0.77, (95% CI 0.61–0.96), p = 0.02].Conclusion: This study provides evidence for the prognostic importance of absolute BK viremia kinetics as a dynamic parameter indicating short-term graft survival independently of other established risk factors.

BK Polyomavirus Activates HSF1 Stimulating Human Kidney Hek293 Cell Proliferation

Objectives. Some DNA viruses, such as BKPyV, are capable of inducing neoplastic transformation in human tissues through still unclear mechanisms. The goal of this study is to investigate the carcinogenic potential of BK polyomavirus (BKPyV) in human embryonic kidney 293 (Hek293) cells, dissecting the molecular mechanism that determines the neoplastic transformation. Materials and Methods. BKPyV, isolated from urine samples of infected patients, was used to infect monolayers of Hek293 cells. Subsequently, intracellular redox changes, GSH/GSSH concentration by HPLC, and reactive oxygen/nitrogen species (ROS/RNS) production were monitored. Moreover, to understand the signaling pathway underlying the neoplastic transformation, the redox-sensitive HFS1-Hsp27 molecular axis was examined using the flavonoid quercetin and polishort hairpin RNA technologies. Results. The data obtained show that while BKPyV replication is closely linked to the transcription factor p53, the increase in Hek293 cell proliferation is due to the activation of the signaling pathway mediated by HSF1-Hsp27. In fact, its inhibition blocks viral replication and cell growth, respectively. Conclusions. The HSF1-Hsp27 signaling pathway is involved in BKPyV infection and cellular replication and its activation, which could be involved in cell transformation.

The Transcriptome Architecture of Polyomaviruses

Polyomaviruses (PyV) are ubiquitous pathogens that can cause devastating human diseases. Due to the small size of their genomes, PyV utilize complex patterns of RNA splicing to maximize their coding capacity. Despite the importance of PyV to human disease, their transcriptome architecture is poorly characterized. Here, we compare short- and long-read RNA sequencing data from eight human and non-human PyV. We provide a detailed transcriptome atlas for BK polyomavirus (BKPyV), an important human pathogen, and the prototype PyV, simian virus 40 (SV40). We identify pervasive wraparound transcription in PyV, wherein transcription runs through the polyA site and circles the genome multiple times. Comparative analyses identify novel, conserved transcripts that increase PyV coding capacity. One of these conserved transcripts encodes superT, a T antigen containing two RB-binding LxCxE motifs. We find that superT-encoding transcripts are abundant in PyV-associated human cancers. Together, we show that comparative transcriptomic approaches can greatly expand known transcript and coding capacity in one of the simplest and most well-studied viral families.

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

BKPyV poses a serious threat to the health of immunocompromised patients, and there are currently no curative drugs. Understanding the relationship between the virus and intracellular environment contributes to the discovery of antiviral targets.

946. Epidemiology and Long-term Outcomes of BK Polyomavirus Nephropathy in Kidney Solid Organ Transplant Recipients at Texas Children’s Hospital

Background BK Polyomavirus (BKPyV) is an important cause of graft dysfunction and premature graft failure in pediatric kidney transplant recipients (PKTR). Contemporary data on BK viral associated nephropathy (BKVAN) in PKTR are limited. We sought to determine the frequency, associations with, and long-term outcomes of BKVAN in PKTR. Methods A retrospective cohort study of PKTR ≤21 years of age transplanted from 2011-2018 was completed. Primary outcome was BKVAN and secondary outcomes included graft dysfunction and failure. Associations with BKVAN were measured using chi square and Fisher exact tests. Time to BKVAN and graft failure were assessed using Kaplan-Meier plots. Results Among 200 PKTR, 16 (8%) developed BKVAN at a median of 228 days post-transplant. Median (IQR) age at time of transplant for patients with BKVAN was 14 (7-17) years of age. Of those who developed BKVAN, 13/16 (81%) were biopsy proven, 2/16 (13%) were probable and 1/16 (6%) was presumptive. Treatment of BKVAN included reduced immunosuppression (12, 75%), ciprofloxacin (11, 69%), intravenous immunoglobulin (7, 44%), and leflunomide (4, 25%). Simultaneous rejection therapy occurred in two patients (13%). Notably, three patients with BKVAN had negative BKPyV plasma viral loads. Median (IQR) BKPyV viral load in those with positive PCRs was 82,000 (19,315 – 1,106,283) copies/milliliter. Median (IQR) time to clearance of BKPyV from the plasma was 425 (261 – 858) days. There was no association between age at time of transplant, repeat kidney transplant, donor type, underlying diagnosis at time of transplant, HLA mismatch, mode of dialysis, or steroid free immunosuppression and the development of BKVAN. Mean percent change in eGFR yearly post-transplant was -0.066 for those with BKVAN versus -0.091 for those without BKVAN (p=0.35). Graft failure was experienced in 1/16 (6%) PKTR with BKVAN but was not related to BKVAN. There was no difference in time to graft failure (Figure 1, p=0.64) in those who developed BKVAN versus those who did not. Conclusion BKVAN continues to occur in PKTR. No associations were found with the development of BKVAN in our cohort. PKTR with BKVAN did not have an increased rate of eGFR decline nor did they develop graft failure more quickly than those without BKVAN. Disclosures Sarah J. Swartz, MD, Education grant sponsored by Amgen; awarded by Renal Physicians Association (Other Financial or Material Support, Attended Renal Physician Association PAL (Pediatric Advocacy Leadership) Forum in Jun 2019; Program sponsored by Education grant from Amgen, awarded by the Renal Physicians Association for participation)Vifor Fresensius Medical Care Renal Pharma (Scientific Research Study Investigator, Multi-center site PI for phase 3 study to investigate the safety and efficacy of PA21 (Velphoro) and calcium acetate (Phoslyra) sponsored by Vifor Fresensius Medical Care Renal Pharma funded Sept 2016-Oct 2019)

1382. A Prospective Epidemiological Study BK Polyomavirus DNAuria and DNAemia within the First Year after Kidney Transplantation

Background Screening and early detection for the preceding BK polyomavirus (BKV) DNAuria and DNAemia to prevent the occurrence of BK polyomavirus BKV-associated nephropathy (BKPyVAN) among kidney transplant (KT) recipients has not been universally utilized and never assessed in a setting where the resource is limited. Therefore, we aimed to investigate this entity’s incidence, risk factors, and outcome with this intervention at our institution. Methods A prospective study of KT recipients at a tertiary care transplant center in Bangkok, Thailand, was conducted between January 2019 and March 2020. All patients underwent preemptive monitoring of urine and plasma BKV DNA load, measured by quantitative real-time PCR at 1, 2, 3, 6, 9, and 12 months post-KT. Low- and high-level BKV DNAuria was defined as urine BKV DNA load of < and > 7log10 copies/mL, respectively. Low- and high-level BKV DNAemia was defined as plasma BKV DNA load of < and > 4log10 copies/mL, respectively. The incidences were calculated by Kaplan-Meier analysis. The chi-square or student’s T-test compared clinical characteristics between those with and without high-level BKV DNAuria as appropriate. Risk factors of high-level BKV DNAuria were analyzed using Cox proportional hazard model. Results Among 99 evaluable KT recipients, a mean (SD) age was 42 (11) years, 64.6% were male, and 69.6% received an induction immunosuppressive therapy. Within 12 months post-KT, the incidences of low-level BKV DNAuria, high-level BKV DNAuria, low-level BKV DNAemia, and high-level BKV DNAemia were 22.63%, 13.14%, 9.49%, and 5.11%, respectively. High panel reactive antibody (PRA) was associated with high-level BKV DNAuria at 6 and 12 months, (HR 1.02 [95% CI (1.00-1.04)], P=0.019) and (HR 1.02 [95% CI (1.00-1.04)], P=0.023), respectively. Underlying diabetes mellitus was associated with high-level BKV DNAuria (HR 3.49 [95% CI (1.28-9.51)], P=0.015) at six months; however, not at 12 months. There was no allograft rejection directly related to a reduction of immunosuppression for BKV infection observed. Conclusion BKPyV infection is also prevalent among KT recipients in a resource-limited setting, however, without unfavorable consequence. Those with high-level PRA and underlying diabetes could be at risk of high-level BKV DNAuria after KT. Disclosures All Authors: No reported disclosures