BACKGROUND AND HYPOTHESIS:Malignancy, driven by the effects of immunosuppression, is a major complication following kidney transplantation. The widespread and non-pathogenic TT virus (TTV) has emerged as a surrogate of the immune status of its host, with prior studies linking TTV load to insufficient and excessive immunosuppression and thus indirectly to graft rejection and infection. Its relationship to malignancy in kidney transplant recipients is unknown. METHODS:This prospective observational single center study evaluated 428 patients who underwent kidney transplantation between 2016 and 2019. TTV was quantified by qPCR in plasma and the primary outcome was the incidence of the first malignancy during years 2-5 post-transplant. RESULTS:In total 53 patients developed a malignancy (53% cutaneous keratinocyte cancer). The mean log10 TTV load during months 4 to 12 post-transplant (logTTVm4-12) was associated with increased malignancy risk with a hazard ratio (HR) of 1.25 (95% CI 1.02-1.54) in unadjusted analysis and 1.20 (95% CI 0.97-1.48) after adjustment for age, sex, smoking, and body mass index. In a subgroup, the result remained consistent after additional adjustment for tacrolimus and mycophenolate exposure (HR 1.31, 95% CI 1.03-1.67). Patients with logTTVm4-12 > 8, a cut-off we previously proposed to indicate infection risk, had a HR of 2.10 (95% CI 1.22-3.60). CONCLUSIONS:These findings suggest that a high TTV load-indicating a state of intense immunosuppression-predicts malignancy after kidney transplantation. Monitoring TTV as a marker of immunosuppression may offer a novel strategy for personalizing immunosuppressive therapy and reducing cancer risk.

Abstract Retinol-binding protein 4 (RBP4) is a key transporter of all- trans -retinol (vitamin A), circulating in blood as either holo-RBP4 (retinol-bound) or apo-RBP4 (retinol-free). Dysregulated RBP4 levels, particularly an imbalance between apo- and holo-RBP4, have been implicated in a range of metabolic and cardiovascular diseases. Current detection methods such as ELISA and Western blot lack the specificity to distinguish these two forms. Here, we present an aptamer-based biosensing strategy that overcomes this limitation by using selected single aptamer sequences for the precise and selective quantification of apo- and holo-RBP4 on graphene field-effect transistor (gFET) sensors. The specific contribution to this study is the identification of individual apo- and holo-RBP4-binding aptamers from previously enriched polyclonal libraries, their computational evaluation by molecular docking and molecular dynamics simulations, as well as their implementation as isoform-selective recognition elements on gFET sensors. The polyclonal aptamer libraries previously were generated using FluMag-SELEX (FluMag- S ystematic E volution of L igands by Ex ponential Enrichment) that are specific to each RBP4 conformer. Next-generation sequencing and bioinformatic enrichment analyses identified two highly specific and high-affinity aptamers, which were further characterized via computational modelling, including molecular docking and molecular dynamics simulations. This structural approach elucidated the conformer-specific binding mechanisms, demonstrating aptamers’ capacity to differentiate subtle protein conformational changes. The selected aptamers were immobilized on gFET devices, enabling label-free, real-time detection with picomolar sensitivity—a 100-fold improvement over the original libraries. Increased aptamer density on the sensor surface further enhanced signal sensitivity by an order of magnitude. These findings validate the use of aptamers as high-performance biorecognition elements in biosensors, offering a path toward precise RBP4 isoform monitoring.

Extracorporeal membrane oxygenation (ECMO) is used to manage severe acute respiratory distress syndrome (ARDS) and is associated with immune modulation. Torque teno virus (TTV) has been proposed as a surrogate marker of immune competence, but it remains unclear whether ECMO influences TTV levels. In this exploratory, retrospective, single-center cohort study, TTV DNA was quantified by qPCR in 174 paired bronchoalveolar lavage (BAL) and plasma samples from 50 adults with COVID-19-associated ARDS. Plasma samples from 40 healthy blood donors were included as controls for baseline comparison. We compared TTV loads between ECMO and non-ECMO patients, assessed longitudinal trends, examined BAL-plasma correlation, and explored associations with mortality and secondary infections. Early plasma TTV in COVID-19 ARDS was lower than in healthy controls (3.20 × 102 vs 6.31 × 101 c/ml, p = 0.041). However, linear regression in log space showed significant growth in BAL and plasma TTV loads over time (R2 = 0.1813 and 0.2720 respectively, p < 0.0001). Longitudinal BAL and plasma TTV loads were closely correlated (R = 0.8295, p < 0.0001) although BAL TTV loads were consistently higher (p < 0.001). Early BAL and plasma TTV loads did not differ significantly between ECMO and non-ECMO patients and showed poor discrimination for ICU mortality and burden of secondary infections. While TTV load showed compartment-specific and time-dependent kinetics in COVID-19-associated ARDS, it was not associated with ECMO status. Early TTV levels did not predict mortality or secondary infections, arguing against its use as a standalone biomarker in this setting.

Polyomavirus nephropathy (BKPyVAN) is a major cause of allograft dysfunction after kidney transplantation (KTX). While plasma BKPyV-PCR is the diagnostic gold standard, it may not fully reflect tissue injury. We conducted a prospective observational proof-of-concept study in 30 KTX recipients with BKPyV reactivation (November 2022–February 2024); 21 underwent kidney biopsy, 11 were diagnosed with biopsy-proven (BP)-BKPyVAN. Urine samples were analyzed by flow cytometry to quantify the potential of VP1-positive reno-urinary epithelial cells as a novel non-invasive marker of active tubular damage. The control cohort included 21 virology-negative patients. Median urinary VP1-positivity was higher in BP-BKPyVAN (33%, IQR 27–46) vs. non-BKPyVAN patients (5%, IQR 1–13; p < 0.001). The assay achieved an AUC of 0.98 (95% CI 0.93–1.00, p = 0.0003; cut-off: 11.7%; sensitivity = 91%, specificity = 89%) for BP-BKPyVAN. Longitudinally, median VP1-burden declined from 13% (IQR 4–29) at baseline to 0% (IQR 0–0.4). BKPyV-DNAemia declined rapidly, but plateaued at ∼4 × 102–7 × 102 copies/mL, whereas urinary VP1-positive cells became undetectable. Our preliminary results suggest that combining urinary VP1-positivity with plasma BKPyV-PCR may help distinguish BP-BKPyVAN from non-BKPyVAN within a BKPyV-reactivation cohort. Longitudinal VP1 tracking may indicate resolution of viral infection earlier than DNAemia. These findings are hypothesis-generating and require validation in larger independent cohorts.

In recent years there has been an increase in the diagnoses of sexually transmitted infections (STI) among men who have sex with men (MSM) using human immunodeficiency virus (HIV) pre-exposure prophylaxis (PrEP); however, data on PrEP users in Austria are limited. In June 2020, we initiated a prospective observational cohort study at Vienna General Hospital including PrEP users from Vienna. Participants underwent STI testing quarterly and provided behavioral information using a questionnaire. Between June 2020 and December 2023 a total of 360 individuals (99

Background and objective:BK polyomavirus (BKPyV) poses a significant challenge in kidney transplant (KTX) recipients, potentially leading to BKPyV-associated nephropathy. Prophylactic ureteral stent (UrSt) placement is the standard care following KTX. Emerging data suggest that UrSt may influence the incidence and severity of BKPyV-DNAemia. We hypothesized a dose-dependent relationship between an indwelling UrSt and the risk of BKPyV-DNAemia in KTX recipients. Methods:We included all KTX recipients with detectable BKPyV-DNAemia at the Medical University of Vienna from 2010 to 2021; those without DNAemia served as controls. This nested, retrospective, 1:1 sex- and age-matched case-control study assessed whether UrSt placement and/or its duration was associated with BKPyV. Key findings and limitations:Of 438 KTX recipients, 51.6% of viremic patients had received UrSt, compared with 47% of nonviremic controls. While UrSt placement was not associated with the risk of BKPyV-DNAemia (odds ratio [OR] 1.20, 95% confidence interval [CI] 0.83-1.75), indwelling time of >8 wk was (OR 1.79, 95% CI 1.10-2.93, p = 0.02). In a multivariable analysis, it remained an independent predictor of BKPyV-DNAemia (adjusted OR 1.74, 95% CI 1.06-2.86, p = 0.03). Limitations include the retrospective, single-center study design. Conclusions and clinical implications:Prophylactic UrSt placement after KTX does not increase the risk of developing BKPyV-DNAemia. However, the indwelling time of the UrSt should be limited to <8 wk to reduce the risk of BKPyV-DNAemia. Therefore, early removal of UrSt-preferably within 8 wk-should be pursued when clinically feasible. Further research is needed to define the optimal UrSt indwelling time and clarify the underlying pathophysiological mechanisms. Patient summary:In this study, we examined whether the placement and duration of ureteral stents after kidney transplantation affect the risk of developing a BK polyomavirus that can harm the transplanted organ. We found that the length of time the stent remains in place-especially beyond 8 weeks-was linked to a higher risk of viral reactivation. Removal of the stent earlier may help protect patients from these complications.

The apathogenic and torque teno virus (TTV) is associated with the state of immunosuppression in solid organ transplant recipients. After kidney transplantation, quantification of TTV load may serve as a risk stratification tool for allograft rejection and infectious events. Besides an association between recipient age and sex and immunosuppression with TTV, limited data exists on other potential clinical determinants of TTV load. This retrospective study included 555 adult recipients of a kidney allograft transplanted between January 1st, 2016 and December 31st, 2019 at the Medical University Vienna from the prospective observational TTV-POET trial (institutional review board approval number: 1785/2016; German Clinical Trials Registry number: DRKS00012335; Fig. 1). For the present analysis, we included TTV measurements before transplantation (d0), at month 1 (m1), at month 3 (m3) and at month 12 (m12) after transplantation. TTV DNA was extracted from plasma and assessed by PCR with primers as described by Maggi and colleagues. TTV load was associated with recipient and donor baseline characteristics and follow-up data. Median recipient and donor age at transplantation was 56 years (interquartile range [IQR] 45–64). 188 (34%) kidney allograft recipients were female, 97 patients (18%) had a history of prior kidney transplantation, 476 patients (86%) received a deceased donor kidney transplant. 46 patients (8%) had pre-formed donor-specific antibodies (DSA); 16 patients (3%) received an AB0-incompatbile transplant. Median body-mass index (BMI) was 26 (IQR 23–30), median duration of kidney replacement therapy was 1021 days (IQR, 576–1605). Baseline TTV load was lower in female recipients (p = 0.004) and higher in older recipients (d0: β 0.014, 95% CI: 0.003–0.024, p = 0.01) and recipients with higher BMI (p = 0.03). TTV load within the first year after kidney transplantation was associated with recipient and donor age. Older recipients and recipients from older donors and showed higher TTV loads (older recipients: m3, β 0.014, 95% CI 0.003–0.024, p = 0.001; m12, β 0.019, 95% CI 0.005–0.033, p = 0.007, older donors: m3, β 0.012, 95% CI 0.003–0.021, p = 0.01; m12, β 0.01, 95% CI 0.008–0.034, p = 0.001). TTV load showed a negative correlation with peripheral blood leukocyte and lymphocyte counts during the first year after transplantation (leukocytes: m1, β −0.1, 95% CI −0.14 to −0.05, p < 0.001; m3, β −0.08, 95% CI −0.12 to −0.04, p < 0.001; m12, β −0.14, 95% CI −0.22 to −0.06, <0.001; data on lymphocytes not shown). Additionally, TTV viral load negatively correlated with the estimated glomerular filtration rate (eGFR) the first year after kidney transplantation (m1, β −.001, 95% CI −0.018 to −.002, p < 0.02; m3, β −0.007, 95% CI −0.015 to 0.001, p = 0.1; m12, β −0.019, 95% CI −.03 to 0.007, p = 0.01). Finally, viral load was associated with tacrolimus trough levels in month 12 after transplantation (β 0.09, 95% CI 0.01–0.19, p = 0.04). This first comprehensive analysis on the association between TTV load an baseline donor and recipient characteristics and clinical follow-up in kidney transplant recipients, revealed several novel factors that might influence TTV load: a high BMI might induce additional immunosuppression, a high donor age might indicate introduction of increased TTV load or genotype number from older donors, low leukocytes and lymphocytes might lead to reduced ability for TTV control and a low eGFR might be a proxy for comorbidities. The incorporation of these factors might improve the accuracy of TTV load for immunologic monitoring in routine clinical care.

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) can damage the endothelium and increase arterial stiffness, potentially leading to adverse cardiovascular events. In parallel, systemic inflammation in COVID-19 also impacts endothelial function. Angiotensin-converting enzyme 2 (ACE2) promotes vasodilation and anti-inflammatory effects, but also facilitates SARS-CoV-2 entry into human cells. Thus, concerns have been raised about the use of RAAS inhibitors (RAASi) in COVID-19 patients due to potential ACE2 upregulation. However, the clinical significance of increased plasma ACE2 (sACE2) in RAASi-treated COVID-19 patients remains unclear. Methods: This prospective, single-centre study evaluated RAASi, sACE2, and vascular function in acutely ill patients with COVID-19 in comparison with acutely ill patients without COVID-19. Adult emergency department patients with confirmed or suspected COVID-19 were enrolled and underwent pulse wave velocity, ankle brachial index, and sACE2 measurements. Results: In the 152 included patients (50% female, median age 62 years, 68% COVID-19 positive), the sACE2 values were slightly higher in the COVID-19 (0.485 [0.364-1.329]) than in the non-COVID-19 subgroup (0.458 [0.356-1.138]; p = 0.70). No significant differences in sACE2 were observed between patients with and without RAASi, regardless of COVID-19 status. Pulse wave velocity values differed significantly between groups (p = 0.015). Conclusions: In emergency department patients, sACE2 was upregulated in COVID-19 patients, probably due to oxidative stress and inflammation. RAASi did not increase sACE2, but may have protective effects against inflammation. Elevated sACE2 appeared to have a beneficial effect on arterial stiffness in all patients. These findings support continued RAASi therapy in COVID-19 patients to protect against chronic inflammation and apoptosis.

Objectives To identify occupational subpopulations at risk and predisposing factors for SARS-CoV-2 infections among hospital employees in a large tertiary hospital in Central Europe.Methods In this retrospective observational study, the incidences of SARS-CoV-2 occurring between 2 November 2020 and 1 July 2022, among employees and in the general population, were determined based on real-world data. From the infected personnel, information on sex, age, occupation and vaccination status was obtained and analysed.Results 3812 employees acquired SARS-CoV-2 at least once during the 607-day study period. Particularly high absolute and relative infection rates were noted in staff in operational roles, as demonstrated by 948 infected members or 62.1% of this particular occupational cohort, consisting of 1526 employees. Additionally, infections occurred early in the study period and repeated infections were frequently observed. The numbers of unvaccinated employees were higher and of fully vaccinated employees lower in this occupational group. Vaccinations were further initiated significantly later in the operational staff compared with other occupational groups. Notably, nursing staff and physicians working front line were less frequently tested SARS-CoV-2 positive with 862 out of 3252 (26.5%) and 668 out of 2617 (25.6%) employees, respectively. The weekly epidemic curve in the hospital employees paralleled the observed incidences in the general population, although the proportion of infected was lower in the hospital employees.Conclusions The observed differences in incidences and vaccine acceptance between the individual occupational cohorts showed that providing customised information on disease prevention and vaccination benefits to distinct subgroups is pivotal for hospital management strategies.

This study presents a graphene field-effect transistor (gFET) biosensor with dual detection capabilities for SARS-CoV-2: one RNA detection assay to confirm viral positivity and the other for nucleocapsid (N-)protein detection as a proxy for infectiousness of the patient. This technology can be rapidly adapted to emerging infectious diseases, making an essential tool to contain future pandemics. To detect viral RNA, the highly conserved E-gene of the virus was targeted, allowing for the determination of SARS-CoV-2 presence or absence using nasopharyngeal swab samples. For N-protein detection, specific antibodies were used. Tested on 213 clinical nasopharyngeal samples, the gFET biosensor showed good correlation with RT-PCR cycle threshold values, proving its high sensitivity in detecting SARS-CoV-2 RNA. Specificity was confirmed using 21 pre-pandemic samples positive for other respiratory viruses. The gFET biosensor had a limit of detection (LOD) for N-protein of 0.9 pM, establishing a foundation for the development of a sensitive tool for monitoring active viral infection. Results of gFET based N-protein detection corresponded to the results of virus culture in all 16 available clinical samples and thus it also proved its capability to serve as a proxy for infectivity. Overall, these findings support the potential of the gFET biosensor as a point-of-care device for rapid diagnosis of SARS-CoV-2 infection and indirect assessment of infectiousness in patients, providing additional information for clinical and public health decision-making.

Polyomaviruses have the potential to cause significant morbidity not only in transplant medicine, but also in other forms of disease or variants of immunosuppression. In kidney transplant recipients or recipients of human stem cell transplants, the BK-Virus is the major proponent of manifestations such as BKPyV-associated nephropathy or hemorrhagic cystitis. As no polyomavirus-specific drug with proven in vivo effects has been developed so far, methods to screen for such drugs are important. This work describes the establishment of a virus-secreting cell line. By infecting a pre-established monkey kidney cell line (COS-1) with a non-rearranged human BK polyomavirus isolated from a kidney transplant patient suffering from BKPyV-associated nephropathy, a continuously replicating cell type with consistent virus secretion could be established and was termed COSSA. Measurements of BKPyV replication, virion production, and secretion were performed both intracellularly and in the cell supernatant. Viral proteins such as VP1 and LTAg were accurately tracked by confocal microscopy, as well as by immunoblot and qPCR. An intracellular flow cytometry (FACS) assay detecting VP1 protein was established and revealed an expanded range of positive intracellular signals. The viruses produced proved to be infectious in human tubular epithelial cell lines. Long-range sequencing of the COSSA genome using Oxford Nanopore Technology revealed a total of five distinct BKPyV integration events. One integration of a partial BKPyV genome was located upstream of the epidermal growth factor receptor gene. The second and third, both truncated forms of integration, were close to histocompatibility gene locuses, while the fourth was characterized by a ninefold and the fifth by a fourfold tandem repeat of the BKPyV genome. From both of the repeat forms, virus replicates were derived showing deletions/duplications on early and late genes and inversions within the non-coding control region (NCCR). This pattern of repetitive viral genome integration is a potential key driver of enhanced viral replication and increased virion assembly, ultimately supporting efficient virus egress. Quantitative PCR analysis confirmed the release of approximately 108/mL viral units per 48 h from 2 × 105 COSSA cells into the culture supernatant. Notably, the NCCR region of the most frequent copies of circular virus and the integrated tetrameric tandem repeat exhibited a rearranged configuration, which may contribute to the observed high replication dynamics. The establishment of a consistent methodology to generate and secrete BKPyV from a cell line is expected to significantly facilitate antiviral drug development.

Hemophagocytic lymphohistiocytosis (HLH) is an excessive immune activation with cytokine storm und multi-organ dysfunction. It can occur secondarily, especially due to viral infections like COVID-19. Rapid treatment is crucial for favourable outcomes, but diagnosing HLH is challenging. The most common diagnostic instrument is the H-Score. However, the prognostic value of the H-score has not yet been assessed in detail in the spotlight of secondary HLH in severe COVID-19. COVID-19 patients treated between February 2020 and April 2021 at the intensive care unit (ICU) of the Department of Infectious Diseases and Tropical Medicine, Clinic Favoriten, Vienna, Austria, were included in this study. Data were assessed retrospectively by document review, and the follow-up period was at least 90 days. A total of 208 critically ill COVID-19 patients with an age of 61.8 ± 13.6 years were enrolled in this study. We found an average H-Score in the entire study collective of 94 ± 51 points, and 8.7% had a score ≥ 169 testing positive for HLH. A positive score was associated with increased mortality rates at 28 (66.7 vs. 26.3%, p < 0.001) and 90 days (72.2 vs. 27.9%, p < 0.001). In our cohort study, critically ill COVID-19 patients with an H-Score ≥ 169 during their ICU stay had increased mortality rates at 28 and 90 days. Thus, attention should be paid to individuals with rising or high scores. Therapeutic options and their impact on mortality for patients with COVID-19-associated secondary HLH should be evaluated in further studies.

BACKGROUND AND AIMS:Identification of people living with hepatitis C virus (HCV) via readily available laboratory records could be a key strategy for macro-elimination, aligning with the WHO elimination goal. Therefore, the ELIMINATE(ELIMINation of HCV in AusTria East) project aimed to systematically re-link people with a 'last-positive' HCV-RNA PCR record to care. METHODS:In 10 major liver centres in Eastern Austria, a systematic readout of 'last-positive' HCV-RNA PCR test records obtained between 2008 and 2020 were conducted and linked to available patient contact data. Between 2020 and 2023, individuals were contacted first by phone, then by letter, to inform them about the availability of effective direct-acting antiviral (DAA) treatment and invite them for pre-treatment evaluation. RESULTS:The overall cohort of last-positive HCV+ individuals included 5695 subjects (62.5% males, mean age 57.3 ± 17.3 years); of note, 1931 (34%) of them had died and 759 (13%) individuals had no valid contact information. Of the remaining 3005 individuals, 1171 (40.0%) had already achieved sustained virological response (SVR) at the time of re-call. We successfully reached 617 (20.5%), of whom 417 (67.6%) attended their pre-treatment visit, and 397 (64.3%) commenced DAA-therapy. HCV cure has been confirmed in 326 individuals, corresponding to an SVR rate of 82.1%. CONCLUSION:The ELIMINATE project identified 5695 people living with HCV who were 'lost to care' despite documented HCV viraemia. While invalid contact data were an evident barrier to HCV elimination, premature deaths among the cohort underscored the severity of untreated HCV. The implementation of a systematic HCV-RNA PCR recorded-based re-call workflow represents an effective strategy supporting the WHO goal of HCV elimination.

Torque Teno virus (TTV) is nonpathogenic, highly prevalent, and reflects the immune status of its host. Thus, TTV plasma load was suggested for the guidance of immunosuppression post solid organ transplantation. The present study was designed to determine the kinetics of TTV following changes in calcineurin inhibitor (CNI) dose. A total of 48 adult recipients of a kidney graft transplanted at the Medical University of Vienna between 2018 and 2019 with isolated changes in CNI dose were selected from the prospective TTV-POET trial. TTV plasma load was quantified by in-house PCR. At Day 30 following CNI dose adaptation (median 33% of daily dose) no changes in TTV load were noted. However, at Day 60, following CNI dose reduction a lower TTV load of 6.4 log(10) c/mL (median; interquartile range [IQR] 4.9-8.1) compared with the baseline of 7.1 log(10) c/mL (IQR 5.3-8.9) was noted (p=0.001); there was also a trend toward a higher TTV load following CNI increase (6.6 log(10) c/mL, IQR 4.1-9.7 vs. 5.2 log(10) c/mL, IQR 4.5-6.8; p=0.09). The data suggested that TTV load changes become noticeable only 2 months after CNI dose adaptation, which might be the ideal time point for TTV load monitoring.

BACKGROUND:The 2022 mpox outbreak continues, and while progress has been made in prevention strategies and potential treatment options, data on late sequelae following mpox are scarce. OBJECTIVE:This analysis aimed to assess the incidence of scar formation in individuals affected by the 2022 mpox outbreak. METHODS:All individuals diagnosed with mpox at the Department of Dermatology at the Medical University of Vienna in 2022 were included in this analysis. Follow-up data were collected throughout November 2023. 'Scar formation' was defined as having at least one scar at the former active mpox lesions. RESULTS:At our clinic, 28 cases of mpox presented between June 2022 and October 2022 and exclusively occurred in men who have sex with men (100%, 28/28), of whom 46% (13/28) were living with HIV, and 32% (9/28) were using pre-exposure prophylaxis (PrEP). Secondary bacterial infection of mpox lesions was suspected in six individuals, and all received systemic antibiotics. Overall, 26 were followed up in November 2023 after a median time of 15 months, and scar formations were found in 43% of cases. CONCLUSIONS:Our data provide insights into the late yet cumulating disease burden caused by the 2022 mpox outbreak. Highly effective prevention strategies are warranted to overcome the mpox epidemic and its potential late sequelae.