Longitudinal Testing for Respiratory and Gastrointestinal Shedding of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Day Care Centers in Hesse, Germany.

BACKGROUND: With the pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ongoing in Europe in June 2020, day care centers were reopened in the state of Hesse, Germany, after the lockdown. The role young children play in the dynamics of the transmission was unknown. METHODS: We conducted a longitudinal study over 12 weeks and 2 days (18 June 2020-10 September 2020) to screen attendees and staff from day care centers in the state of Hesse, Germany, for both respiratory and gastrointestinal shedding of SARS-CoV-2. A total of 859 children (age range, 3 months-8 years) and 376 staff members from 50 day care centers, which were chosen representatively from throughout the state, participated in the study. Parents were asked to collect both a buccal mucosa and an anal swab from their children once a week. Staff were asked to self-administer the swabs. Reverse transcriptas polymerase chain reaction for SARS-CoV-2 was performed in a multiple-swab pooling protocol. RESULTS: A total of 7366 buccal mucosa swabs and 5907 anal swabs were analyzed. No respiratory or gastrointestinal shedding of SARS-CoV-2 was detected in any of the children. Shedding of SARS-CoV-2 was detected in 2 staff members from distinct day care centers. One was asymptomatic at the time of testing, and one was symptomatic and did not attend the facility on that day. CONCLUSION: Detection of either respiratory or gastrointestinal shedding of SARS-CoV-2 RNA in children and staff members attending day care centers was rare in the context of limited community activity and with infection prevention measures in the facilities in place.

Evaluation of stability and inactivation methods of SARS-CoV-2 in context of laboratory settings.

The novel coronavirus SARS-CoV-2 is the causative agent of the acute respiratory disease COVID-19, which has become a global concern due to its rapid spread. Laboratory work with SARS-CoV-2 in a laboratory setting was rated to biosafety level 3 (BSL-3) biocontainment level. However, certain research applications in particular in molecular biology require incomplete denaturation of the proteins, which might cause safety issues handling contaminated samples. In this study, we evaluated lysis buffers that are commonly used in molecular biological laboratories for their ability to inactivate SARS-CoV-2. In addition, viral stability in cell culture media at 4 °C and on display glass and plastic surfaces used in laboratory environment was analyzed. Furthermore, we evaluated chemical and non-chemical inactivation methods including heat inactivation, UV-C light, addition of ethanol, acetone-methanol, and PFA, which might be used as a subsequent inactivation step in the case of insufficient inactivation. We infected susceptible Caco-2 and Vero cells with pre-treated SARS-CoV-2 and determined the tissue culture infection dose 50 (TCID50) using crystal violet staining and microscopy. In addition, lysates of infected cells and virus containing supernatant were subjected to RT-qPCR analysis. We have found that guanidine thiocyanate and most of the tested detergent containing lysis buffers were effective in inactivation of SARS-CoV-2, however, the M-PER lysis buffer containing a proprietary detergent failed to inactivate the virus. In conclusion, careful evaluation of the used inactivation methods is required especially for non-denaturing buffers. Additional inactivation steps might be necessary before removal of lysed viral samples from BSL-3.

Clinical performance of different SARS-CoV-2 IgG antibody tests.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serological assays are urgently needed for rapid diagnosis, contact tracing, and for epidemiological studies. So far, there is limited data on how commercially available tests perform with real patient samples, and if positive tested samples show neutralizing abilities. Focusing on IgG antibodies, we demonstrate the performance of two enzyme-linked immunosorbent assay (ELISA) assays (Euroimmun SARS-CoV-2 IgG and Vircell COVID-19 ELISA IgG) in comparison to one lateral flow assay (FaStep COVID-19 IgG/IgM Rapid Test Device) and two in-house developed assays (immunofluorescence assay [IFA] and plaque reduction neutralization test [PRNT]). We tested follow up serum/plasma samples of individuals polymerase chain reaction-diagnosed with COVID-19. Most of the SARS-CoV-2 samples were from individuals with moderate to the severe clinical course, who required an in-patient hospital stay. For all examined assays, the sensitivity ranged from 58.8 to 76.5% for the early phase of infection (days 5-9) and from 93.8% to 100% for the later period (days 10-18).

Clinical Outcome and Viral Genome Variability of Hepatitis B Virus-Induced Acute Liver Failure.

Acute hepatitis B virus (HBV) infection remains a frequent cause of acute liver failure (ALF) worldwide. ALF occurs in 0.1%-0.5% of infected patients. The aim of this study was to scrutinize the outcome of patients with HBV-induced ALF and mutational patterns of HBV variants, which might contribute to ALF. From 2005 to 2016, 42 patients were treated for HBV-induced ALF in the University Hospital Essen, Germany. Clinical and virological data from these patients were collected. As a control, 38 patients with acute hepatitis B (AHB) without liver failure were included. The HBV genome was sequenced by next-generation sequencing (NGS). Mutations that were found by NGS were analyzed in vitro. Of 42 patients, 8 had ALF without spontaneous recovery (NSR): Seven patients underwent liver transplantation (LT) and one patient died before LT. Of 42 patients, 34 (81%) had spontaneous recovery (SR) and cleared the infection, achieving either anti-HBs seroconversion or hepatitis B surface antigen (HBsAg) loss. HBV genotype (GT)-D was the most frequent GT in patients with ALF. Mutations in HBV core, preS2, and small hepatitis B surface antigen (SHB) were more frequent in patients with ALF-NSR compared with those with ALF-SR or AHB. Amino acid deletions (del; 16-22 and 20-22) in preS2 and SHB mutation L49R were exclusively detected in patients with ALF-NSR. In vitro analyses reveal that these mutations did not influence HBsAg secretion or infectivity. Conclusion: HBV GT-D and increased variability in HBV core, preS2 region, and SHB are associated with a worse clinical outcome of acute HBV infection.

Optimized qRT-PCR Approach for the Detection of Intra- and Extra-Cellular SARS-CoV-2 RNAs.

The novel coronavirus SARS-CoV-2 is the causative agent of the acute respiratory disease COVID-19, which has become a global concern due to its rapid spread. Meanwhile, increased demand for testing has led to a shortage of reagents and supplies and compromised the performance of diagnostic laboratories in many countries. Both the World Health Organization (WHO) and the Center for Disease Control and Prevention (CDC) recommend multi-step RT-PCR assays using multiple primer and probe pairs, which might complicate the interpretation of the test results, especially for borderline cases. In this study, we describe an alternative RT-PCR approach for the detection of SARS-CoV-2 RNA that can be used for the probe-based detection of clinical isolates in diagnostics as well as in research labs using a low-cost SYBR green method. For the evaluation, we used samples from patients with confirmed SARS-CoV-2 infections and performed RT-PCR assays along with successive dilutions of RNA standards to determine the limit of detection. We identified an M-gene binding primer and probe pair highly suitable for the quantitative detection of SARS-CoV-2 RNA for diagnostic and research purposes.

Infectivity and stability of hepatitis C virus in different perfusion solutions.

BACKGROUND: Owing to organ shortage, transplantation of organs from HCV (hepatitis C virus) viremic donors into HCV negative individuals is getting more and more accepted. However, transmission of HCV to the host is nearly universal. Until now it is unknown if preservation solutions (PS) might alter infectivity and stability of HCV in the transplant setting. Therefore, seven different preservation solutions (PS) with variable composition were tested in vitro for their direct anti- and proviral effects on HCV. METHODS: In vitro grown HCV based on the JFH-1 isolate was used to characterize the effect of seven different PS on the HCV replication cycle including HCV attachment, entry, replication, and assembly. In addition, HCV stability in PS was tested. RESULTS: Overall, 6/7 PS enhanced HCV infectivity: IGL-1 increased HCV attachment and entry, UW Belzer and Perfadex boosted HCV entry. Production of novel viral particles was enhanced in HTK, UW Belzer, and IGL-1. In contrast, viral replication was significantly reduced in HTK solution while all other PS had no effect on HCV RNA replication. HCV was significantly more stable in HTK solution. Euro Collins was the only PS that did not support HCV infectivity in cell culture. None of the used PS showed cytotoxic effects. CONCLUSION: Our data indicate that HCV infectivity and stability is maintained by several PS.

Methylene Blue Treatment of Grafts During Cold Ischemia Time Reduces the Risk of Hepatitis C Virus Transmission.

Background: Although organ shortage is a rising problem, organs from hepatitis C virus (HCV) ribonucleic acid (RNA)-positive donors are not routinely transplanted in HCV-negative individuals. Because HCV only infects hepatocytes, other organs such as kidneys are merely contaminated with HCV via the blood. In this study, we established a protocol to reduce HCV virions during the cold ischemic time. Methods: Standard virological assays were used to investigate the effect of antivirals, including methylene blue (MB), in different preservation solutions. Kidneys from mini pigs were contaminated with Jc1 or HCV RNA-positive human serum. Afterwards, organs were flushed with MB. Hypothermic machine perfusion was used to optimize reduction of HCV. Results: Three different antivirals were investigated for their ability to inactivate HCV in vitro. Only MB completely inactivated HCV in the presence of all perfusion solutions. Hepatitis C virus-contaminated kidneys from mini pigs were treated with MB and hypothermic machine perfusion without any negative effect on the graft. Human liver-uPA-SCID mice did not establish HCV infection after inoculation with flow through from these kidneys. Conclusions: This proof-of-concept study is a first step to reduce transmission of infectious HCV particles in the transplant setting and might serve as a model for other relevant pathogens.

Scavenger receptor class B member 1 (SCARB1) variants modulate hepatitis C virus replication cycle and viral load.

BACKGROUND & AIMS: There are numerous coding and non-coding variants in the SCARB1 gene that encodes scavenger receptor class B member 1 (SR-BI), a key receptor for both high density lipoproteins and hepatitis C virus (HCV). Many have been linked to clinical phenotypes, yet their impact on the HCV replication cycle is incompletely understood. The aim of this study was to analyze the impact of these variants on the molecular biology and clinical course of HCV. METHODS: We analyzed key coding non-synonymous as well as non-coding SCARB1 variants using virological in vitro and human genetics approaches. RESULTS: Non-synonymous variants: S112F and T175A have greatly reduced HCV receptor function. When present on the cell surface, these variants are impaired in their ability to interact with HCV E2. Non-coding variants: The G allele in rs3782287 is associated with decreased viral load. Haplotype analysis confirmed these findings and identified haplotype rs3782287 A/rs5888 C as a risk allele associated with increased viral load. We also detected a trend towards lower hepatic SR-BI expression in individuals with the rs3782287 GG genotype associated with low viral load suggesting a potential underlying mechanism. CONCLUSION: Coding and non-coding genetic SCARB1 variants modulate the HCV replication cycle and possibly clinical features of hepatitis C. These findings underscore the relevance of SR-BI as an HCV receptor and contribute to our understanding of inter-individual variation in HCV infection. LAY SUMMARY: The cell surface receptor SR-BI (scavenger receptor class B member 1), is essential for hepatitis C virus (HCV) entry into hepatocytes. Variations in the gene coding this receptor influence infectivity and viral load. We analyzed these variations to gain a better understanding of inter-individual differences over the course of HCV infection.

Host cell mTORC1 is required for HCV RNA replication.

OBJECTIVE: Chronically HCV-infected orthotopic liver transplantation (OLT) recipients appear to have improved outcomes when their immunosuppressive regimen includes a mammalian target of rapamycin (mTOR) inhibitor. The mechanism underlying this observation is unknown. DESIGN: We used virological assays to investigate mTOR signalling on the HCV replication cycle. Furthermore, we analysed HCV RNA levels of 42 HCV-positive transplanted patients treated with an mTOR inhibitor as part of their immunosuppressive regimen. RESULTS: The mTOR inhibitor rapamycin was found to be a potent inhibitor for HCV RNA replication in Huh-7.5 cells as well as primary human hepatocytes. Half-maximal inhibition was observed at 0.01 µg/mL, a concentration that is in the range of serum levels seen in transplant recipients and does not affect cell proliferation. Early replication cycle steps such as cell entry and RNA translation were not affected. Knockdown of raptor, an essential component of mTORC1, but not rictor, an essential component of mTORC2, inhibited viral RNA replication. In addition, overexpression of raptor led to higher viral RNA replication, demonstrating that mTORC1, but not mTORC2, is required for HCV RNA replication. In 42 HCV-infected liver-transplanted or kidney-transplanted patients who were switched to an mTOR inhibitor, we could verify that mTOR inhibition decreased HCV RNA levels in vivo. CONCLUSIONS: Our data identify mTORC1 as a novel HCV replication factor. These findings suggest an underlying mechanism for the observed benefits of mTOR inhibition in HCV-positive OLT recipients and potentiate further investigation of mTOR-containing regimens in HCV-positive recipients of solid organ transplants.

Characterization of the inhibition of hepatitis C virus entry by in vitro-generated and patient-derived oxidized low-density lipoprotein.

UNLABELLED: Oxidized low-density lipoprotein (oxLDL) has been reported as an inhibitor of hepatitis C virus (HCV) cell entry, making it the only known component of human lipid metabolism with an antiviral effect on HCV. However, several questions remain open, including its effect on full-length cell-culture-grown HCV (HCVcc) of different genotypes or on other steps of the viral replication cycle, its mechanism of action, and whether endogenous oxLDL shares the anti-HCV properties of in vitro-generated oxLDL. We combined molecular virology tools with oxLDL serum measurements in different patient cohorts to address these questions. We found that oxLDL inhibits HCVcc at least as potently as HCV pseudoparticles. There was moderate variation between genotypes, with genotype 4 appearing the most oxLDL sensitive. Intracellular RNA replication and assembly and release of new particles were unaffected. HCV particles entering target cells lost oxLDL sensitivity with time kinetics parallel to anti-SR-BI (scavenger receptor class B type I), but significantly earlier than anti-CD81, suggesting that oxLDL acts by perturbing interaction between HCV and SR-BI. Finally, in chronically HCV-infected individuals, endogenous serum oxLDL levels did not correlate with viral load, but in HCV-negative sera, high endogenous oxLDL had a negative effect on HCV infectivity in vitro. CONCLUSION: oxLDL is a potent pangenotype HCV entry inhibitor that maintains its activity in the context of human serum and targets an early step of HCV entry.

Ultrasound presentation of abdominal tuberculosis in a German tertiary care center.

OBJECTIVE: Abdominal tuberculosis (TB) is a relatively rare disease in most of Europe and the typical clinical and sonographic findings in this setting have not been studied. We aimed to define sonographic findings that should alert an examiner to the possibility of abdominal TB in a low endemic region. METHODS: Case records of 17 patients with proven (n = 11) or highly likely (n = 6) abdominal TB detected in the gastrointestinal ultrasound unit at a German tertiary care center in 2003-2013 were analyzed retrospectively. Findings were compared with reported series from high-prevalence regions. RESULTS: While 76% of patients had an immigrant background, only 35% had a condition associated with immunosuppression. Lymphadenopathy was present in all cases of abdominal TB, while it was absent in 28% of patients from a control group with proven abdominal sarcoidosis. Moreover, retroperitoneal lymphadenopathy was significantly more common in TB. Other findings in patients with abdominal TB in descending order of frequency were ascites, altered hepatic texture, splenomegaly, splenic lesions, peritoneal thickening, intestinal wall lesions, hepatic lesions and hepatomegaly. 76% of abdominal TB patients had 2 or more pathological findings. CONCLUSIONS: Multiple pathological intra-abdominal findings including lymphadenopathy should alert the examiner to the possibility of abdominal TB.

Impact of intra- and interspecies variation of occludin on its function as coreceptor for authentic hepatitis C virus particles.

Hepatitis C virus (HCV) is characterized by a narrow host range and high interindividual variability in the clinical course of infection. Both of these traits are thought to be largely due to genetic variation between species and between individual hosts. The tight junction component occludin (OCLN) is essential for HCV entry into host cells, and the differences between human and murine OCLN are thought to account in part for the inability of HCV to infect mice and hence preclude their use as a convenient small-animal model. This study assesses the impact of genetic variation in OCLN on cell culture-grown HCV (HCVcc) using a newly generated and characterized OCLN(low) subclone of the Huh-7.5 cell line (Huh-7.5 subclone in which endogenous OCLN expression has been downregulated by a short hairpin RNA). We report the frequency of coding nonsynonymous single nucleotide polymorphisms, i.e., polymorphisms resulting in amino acid exchanges, present in the human population and determine their ability to function as HCV (co)receptors. Moreover, we show that murine OCLN can sustain HCVcc entry, albeit with about 5-fold reduced efficiency compared to that of human OCLN. This reduction in efficiency is due solely to two amino acid residues previously identified by others using an HCV pseudoparticle approach. Finally, we use the Huh-7.5/OCLN(low) cell line to show that HCV spread between neighboring cells is strictly dependent on OCLN.

Neutralization Assay for SARS-CoV-2 Infection: Plaque Reduction Neutralization Test.

Neutralization assays are often used as part of research and diagnostics to detect neutralizing antibodies and to determine a possible protective antibody titer after infection or vaccination. Here we describe a conventional plaque reduction neutralization test (PRNT) to check the presence of antibodies against SARS-CoV-2 in patient samples (serum or plasma).

The Comparative Clinical Performance of Four SARS-CoV-2 Rapid Antigen Tests and Their Correlation to Infectivity In Vitro.

Due to globally rising numbers of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, resources for real-time reverse-transcription polymerase chain reaction (rRT-PCR)-based testing have been exhausted. In order to meet the demands of testing and reduce transmission, SARS-CoV-2 antigen-detecting rapid diagnostic tests (Ag-RDTs) are being considered. These tests are fast, inexpensive, and simple to use, but whether they detect potentially infectious cases has not been well studied. We evaluated three lateral flow assays (RIDA®QUICK SARS-CoV-2 Antigen (R-Biopharm), SARS-CoV-2 Rapid Antigen Test (Roche)), and NADAL® COVID-19 Ag Test (Nal von Minden GmbH, Regensburg, Germany) and one microfluidic immunofluorescence assay (SARS-CoV-2 Ag Test (LumiraDx GmbH, Cologne, Germany)) using 100 clinical samples. Diagnostic rRT-PCR and cell culture testing as a marker for infectivity were performed in parallel. The overall Ag-RDT sensitivity for rRT-PCR-positive samples ranged from 24.3% to 50%. However, for samples with a viral load of more than 6 log10 RNA copies/mL (22/100), typically seen in infectious individuals, Ag-RDT positivity was between 81.8% and 100%. Only 51.6% (33/64) of the rRT-PCR-positive samples were infectious in cell culture. In contrast, three Ag-RDTs demonstrated a more significant correlation with cell culture infectivity (61.8-82.4%). Our findings suggest that large-scale SARS-CoV-2 Ag-RDT-based testing can be considered for detecting potentially infective individuals and reducing the virus spread.

A SARS-CoV-2 cytopathicity dataset generated by high-content screening of a large drug repurposing collection.

SARS-CoV-2 is a novel coronavirus responsible for the COVID-19 pandemic, in which acute respiratory infections are associated with high socio-economic burden. We applied high-content screening to a well-defined collection of 5632 compounds including 3488 that have undergone previous clinical investigations across 600 indications. The compounds were screened by microscopy for their ability to inhibit SARS-CoV-2 cytopathicity in the human epithelial colorectal adenocarcinoma cell line, Caco-2. The primary screen identified 258 hits that inhibited cytopathicity by more than 75%, most of which were not previously known to be active against SARS-CoV-2 in vitro. These compounds were tested in an eight-point dose response screen using the same image-based cytopathicity readout. For the 67 most active molecules, cytotoxicity data were generated to confirm activity against SARS-CoV-2. We verified the ability of known inhibitors camostat, nafamostat, lopinavir, mefloquine, papaverine and cetylpyridinium to reduce the cytopathic effects of SARS-CoV-2, providing confidence in the validity of the assay. The high-content screening data are suitable for reanalysis across numerous drug classes and indications and may yield additional insights into SARS-CoV-2 mechanisms and potential therapeutic strategies.

Detection of SARS-CoV-2 in raw and treated wastewater in Germany - Suitability for COVID-19 surveillance and potential transmission risks.

Wastewater-based monitoring of the spread of the new SARS-CoV-2 virus, also referred to as wastewater-based epidemiology (WBE), has been suggested as a tool to support epidemiology. An extensive sampling campaign, including nine municipal wastewater treatment plants, has been conducted in different cities of the Federal State of North Rhine-Westphalia (Germany) on the same day in April 2020, close to the first peak of the corona crisis. Samples were processed and analysed for a set of SARS-CoV-2-specific genes, as well as pan-genotypic gene sequences also covering other coronavirus types, using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Additionally, a comprehensive set of chemical reference parameters and bioindicators was analysed to characterize the wastewater quality and composition. Results of the RT-qPCR based gene analysis indicate the presence of SARS-CoV-2 genetic traces in different raw wastewaters. Furthermore, selected samples have been sequenced using Sanger technology to confirm the specificity of the RT-qPCR and the origin of the coronavirus. A comparison of the particle-bound and the dissolved portion of SARS-CoV-2 virus genes shows that quantifications must not neglect the solid-phase reservoir. The infectivity of the raw wastewater has also been assessed by viral outgrowth assay with a potential SARS-CoV-2 host cell line in vitro, which were not infected when exposed to the samples. This first evidence suggests that wastewater might be no major route for transmission to humans. Our findings draw attention to the need for further methodological and molecular assay validation for enveloped viruses in wastewater.

Brief clinical evaluation of six high-throughput SARS-CoV-2 IgG antibody assays.

Serological SARS-CoV-2 assays are urgently needed for diagnosis, contact tracing and for epidemiological studies. So far, there is limited data on how recently commercially available, high-throughput immunoassays, using different recombinant SARS-CoV-2 antigens, perform with clinical samples. Focusing on IgG and total antibodies, we demonstrate the performance of four automated immunoassays (Abbott Architect™ i2000 (N protein-based)), Roche cobas™ e 411 analyzer (N protein-based, not differentiating between IgA, IgM or IgG antibodies), LIAISON®XL platform (S1 and S2 protein-based), VIRCLIA® automation system (S1 and N protein-based) in comparison to two ELISA assays (Euroimmun SARS-CoV-2 IgG (S1 protein-based) and Virotech SARS-CoV-2 IgG ELISA (N protein-based)) and an in-house developed plaque reduction neutralization test (PRNT). We tested follow up serum/plasma samples of individuals PCR-diagnosed with COVID-19. When calculating the overall sensitivity, in a time frame of 49 days after first PCR-positivity, the PRNT as gold standard, showed the highest sensitivity with 93.3% followed by the dual-target assay for the VIRCLIA® automation system with 89%. The overall sensitivity in the group of N protein-based assays ranged from 66.7 to 77.8% and in the S protein-based-assays from 71.1 to 75.6%. Five follow-up samples of three individuals were only detected in either an S and/or N protein-based assay, indicating an individual different immune response to SARS-CoV-2 and the influence of the used assay in the detection of IgG antibodies. This should be further analysed. The specificity of the examined assays was ≥ 97%. However, because of the low or unknown prevalence of SARS-CoV-2, the examined assays in this study are currently primarily eligible for epidemiological investigations, as they have limited information in individual testing.

Sofosbuvir Activates EGFR-Dependent Pathways in Hepatoma Cells with Implications for Liver-Related Pathological Processes.

Direct acting antivirals (DAAs) revolutionized the therapy of chronic hepatitis C infection. However, unexpected high recurrence rates of hepatocellular carcinoma (HCC) after DAA treatment became an issue in patients with advanced cirrhosis and fibrosis. In this study, we aimed to investigate an impact of DAA treatment on the molecular changes related to HCC development and progression in hepatoma cell lines and primary human hepatocytes. We found that treatment with sofosbuvir (SOF), a backbone of DAA therapy, caused an increase in EGFR expression and phosphorylation. As a result, enhanced translocation of EGFR into the nucleus and transactivation of factors associated with cell cycle progression, B-MYB and Cyclin D1, was detected. Serine/threonine kinase profiling identified additional pathways, especially the MAPK pathway, also activated during SOF treatment. Importantly, the blocking of EGFR kinase activity by erlotinib during SOF treatment prevented all downstream events. Altogether, our findings suggest that SOF may have an impact on pathological processes in the liver via the induction of EGFR signaling. Notably, zidovudine, another nucleoside analogue, exerted a similar cell phenotype, suggesting that the observed effects may be induced by additional members of this drug class.

Role of BK polyomavirus (BKV) and Torque teno virus (TTV) in liver transplant recipients with renal impairment.

PURPOSE: Renal impairment is a common complication after liver transplantation (LT). While BK polyomavirus (BKV) has been linked to renal failure in kidney transplant recipients, Torque teno virus (TTV) is a surrogate marker for immunosuppression that does not have a clear association with any human disease. The impact of BKV and TTV on renal impairment after LT is unknown. METHODOLOGY: In this retrospective study, urine and serum samples from 136 liver transplant recipients were screened for BKV and TTV by quantitative PCR. In addition, serum was screened for BKV-specific antibodies and the VP1 typing region was sequenced for BKV genotyping. All parameters were correlated with clinical data.Results/Key findings. BK viruria was detected up to 21 years after transplantation in 16.9 % of cases. BK viraemia was detected in 8.7 % of patients with BK viruria up to 4 years after LT. BKV-specific antibodies were detected in 93.6 % of all LT recipients and correlated with BKV viral load in urine. There was no correlation between renal impairment and the detection of BK DNA in urine (OR 0.983). TTV DNA was detected in 84.6 % of serum samples and in 66.6 % of urine samples. The TTV viral load in serum correlated with the BKV viral load but had no impact on renal impairment. CONCLUSION: Our data indicate that the detection of BKV and TTV is not a risk factor for renal impairment after LT. A correlation of TTV and BKV viral load seems to be an indicator for the immune status of the host.