The glutamate receptor antagonist ifenprodil inhibits hepatitis E virus infection.

Infection with hepatitis E virus (HEV) represents a global problem, with over 20 million people infected annually. No specific antiviral drugs are available for treating HEV infection, necessitating the development of novel targeted therapeutics. Here, we report that the N-methyl-D-aspartate receptor (NMDAR) antagonist ifenprodil, a clinically approved drug used to treat idiopathic pulmonary fibrosis (IPF), is an HEV inhibitor in liver-derived cells. In vitro investigation demonstrates that ifenprodil suppresses viral protein expression in a dose-dependent manner in human hepatoma cells by inhibiting early stages of viral infection. We also found that ifenprodil modulates host cell intrinsic biological processes distinct from virus-induced innate immunity, inhibiting HEV RNA accumulation in primary human hepatocytes. Finally, the inhibitory effect of ifenprodil in vivo was also tested in rabbits challenged with the HEV-3ra CHN-BJ-R14 strain. Fecal virus shedding was below the limit of detection in two animals for both ribavirin-treated and ifenprodil-treated rabbits compared to vehicle-treated control animals. Our data demonstrate that ifenprodil is an effective anti-HEV compound with potential as a therapeutic candidate for the treatment of HEV infection.

The triglyceride-synthesizing enzyme diacylglycerol acyltransferase 2 modulates the formation of the hepatitis C virus replication organelle.

The replication organelle of hepatitis C virus (HCV), called membranous web, is derived from the endoplasmic reticulum (ER) and mainly comprises double membrane vesicles (DMVs) that concentrate the viral replication complexes. It also tightly associates with lipid droplets (LDs), which are essential for virion morphogenesis. In particular acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1), a rate-limiting enzyme in triglyceride synthesis, promotes early steps of virus assembly. The close proximity between ER membranes, DMVs and LDs therefore permits the efficient coordination of the HCV replication cycle. Here, we demonstrate that exaggerated LD accumulation due to the excessive expression of the DGAT1 isozyme, DGAT2, dramatically impairs the formation of the HCV membranous web. This effect depended on the enzymatic activity and ER association of DGAT2, whereas the mere LD accumulation was not sufficient to hamper HCV RNA replication. Our lipidomics data indicate that both HCV infection and DGAT2 overexpression induced membrane lipid biogenesis and markedly increased phospholipids with long chain polyunsaturated fatty acids, suggesting a dual use of these lipids and their possible competition for LD and DMV biogenesis. On the other hand, overexpression of DGAT2 depleted specific phospholipids, particularly oleyl fatty acyl chain-containing phosphatidylcholines, which, in contrast, are increased in HCV-infected cells and likely essential for viral infection. In conclusion, our results indicate that lipid exchanges occurring during LD biogenesis regulate the composition of intracellular membranes and thereby affect the formation of the HCV replication organelle. The potent antiviral effect observed in our DGAT2 overexpression system unveils lipid flux that may be relevant in the context of steatohepatitis, a hallmark of HCV infection, but also in physiological conditions, locally in specific subdomains of the ER membrane. Thus, LD formation mediated by DGAT1 and DGAT2 might participate in the spatial compartmentalization of HCV replication and assembly factories within the membranous web.

Epidemiology and global spread of emerging tick-borne Alongshan virus.

The emergence and spread of novel viral pathogens is a major threat to human health, particularly in the context of climate and human-induced change in land use. Alongshan virus (ALSV) is a tick-borne virus associated with human disease, which was first identified in northeast China. More recently, several studies reported the emergence of ALSV in mammalian and arthropod hosts in multiple different countries outside of Asia, and the first viral genome sequencing data has become available. ALSV is a member of the Jingmenvirus group closely related to the Flaviviridae family. Unusually, the positive-sense, single-stranded RNA genome of ALSV is segmented and consists of four distinct segments, two of which show homology with the NS3 and NS5 protein encoding regions of non-segmented flaviviruses. Transmission of arthropod-borne pathogens will likely increase in the future due to environmental change mediated by a variety of environmental and ecological factors and increasing human encroachment into wild animal habitats. In this review, we present current knowledge of global ALSV distribution and emergence patterns, highlight genetic diversity, evolution and susceptible species. Finally, we discuss the role of this emerging tick-borne virus in the context of urbanization and global health.

Divergent autoantibody and cytokine levels in COVID-19 sepsis patients influence survival.

Studies have pointed to a decisive role of autoantibodies in the context of sepsis and severe Coronavirus disease 2019 (COVID-19), which itself often fulfills the criteria for sepsis, including dysregulated immune responses and organ dysfunction. To directly compare and further analyze the autoantibody profiles of sepsis patients with and without COVID-19, the luciferase immunoprecipitation systems (LIPS) assay was used to measure the levels of autoantibodies against a variety of clinically relevant cytokines, lung-associated proteins, other autoantigens, and antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In addition, cytokine titers were measured with the LEGENDplex™ Human Antivirus Response Panel. We observed significantly increased levels of autoantibodies in 59% of the COVID-19-Sepsis group compared to 48% of the Sepsis group. Significant differences were identified between the groups for the levels of autoantibodies against gATPase. The cytokine levels of interferon (IFN)-λ1 and IP-10 were higher in the COVID-19-Sepsis group compared to the Sepsis group. Additional correlations between autoantibodies, cytokines and 30-day survival could be demonstrated, suggesting varied underlying pathological mechanisms. Elevated levels of cytokines and autoantibodies may serve as prognostic indicators for the survival probability of sepsis patients, highlighting the intricate relationship between immune responses and patient outcomes in the context of both sepsis and COVID-19.

MicroRNAs modulate SARS-CoV-2 infection of primary human hepatocytes by regulating the entry factors ACE2 and TMPRSS2.

BACKGROUND AND AIMS: Severe acute respiratory syndrome coronavirus (SARS-CoV-2) preferentially infects the respiratory tract; however, several studies have implicated a multi-organ involvement. Hepatic dysfunctions caused by SARS-CoV-2 infection have been increasingly recognized and described to correlate with disease severity. To elucidate molecular factors that could contribute towards hepatic infection, we concentrated on microRNAs (miRNAs), a class of small non-coding RNAs that modulate various cellular processes and which are reported to be differentially regulated during liver injury. We aimed to study the infection of primary human hepatocytes (PHH) with SARS-CoV-2 and to evaluate the potential of miRNAs for modulating viral infection. METHODS: We analysed liver autopsies from a coronavirus disease 19 (COVID-19)-positive cohort for the presence of viral RNA using Nanopore sequencing. PHH were used for the infection with SARS-CoV-2. The candidate miRNAs targeting angiotensin converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) were identified using in silico approaches. To discover the potential regulatory mechanism, transfection experiments, qRT-PCRs, western blots and luciferase reporter assays were performed. RESULTS: We could detect SARS-CoV-2 RNA in COVID-19-positive liver autopsies. We show that PHH express ACE2 and TMPRSS2 and can be readily infected with SARS-CoV-2, resulting in robust replication. Transfection of selected miRNA mimics reduced SARS-CoV-2 receptor expression and SARS-CoV-2 burden in PHH. In silico and biochemical analyses supported a potential direct binding of miR-141-3p to the SARS-CoV-2 genome. CONCLUSION: We confirm that PHH are susceptible to SARS-CoV-2 infection and demonstrate selected miRNAs targeting SARS-CoV-2 entry factors and/or the viral genome reduce viral loads. These data provide novel insights into hepatic susceptibility to SARS-CoV-2 and associated dysfunctions in COVID-19.

Hepatitis E virus: from innate sensing to adaptive immune responses.

Hepatitis E virus (HEV) infections are a major cause of acute viral hepatitis in humans worldwide. In immunocompetent individuals, the majority of HEV infections remain asymptomatic and lead to spontaneous clearance of the virus, and only a minority of individuals with infection (5-16%) experience symptoms of acute viral hepatitis. However, HEV infections can cause up to 30% mortality in pregnant women, become chronic in immunocompromised patients and cause extrahepatic manifestations. A growing body of evidence suggests that the host immune response to infection with different HEV genotypes is a critical determinant of distinct HEV infection outcomes. In this Review, we summarize key components of the innate and adaptive immune responses to HEV, including the underlying immunological mechanisms of HEV associated with acute and chronic liver failure and interactions between T cell and B cell responses. In addition, we discuss the current status of vaccines against HEV and raise outstanding questions regarding the immune responses induced by HEV and treatment of the disease, highlighting areas for future investigation.

Performance of sofosbuvir and NITD008 in extrahepatic neuronal cells against HEV.

Hepatitis E is an underestimated disease, leading to estimated 20 million infections and up to 70,000 deaths annually. Infections are mostly asymptomatic, but can reach mortality rates up to 25% in pregnant women or become chronic in immunocompromised patients. Hepatitis E virus (HEV) infection have been associated with a range of extrahepatic manifestations, including a spectrum of neurological symptoms. Current therapy options are limited to non-specific antivirals like ribavirin, but recently, repurposed viral polymerase inhibitors like sofosbuvir and NITD008 were described to inhibit HEV replication. Here, we evaluated the efficacy of these drugs in various neuronal-derived cell lines to determine their potency outside the liver. Our findings indicate that both drugs, especially sofosbuvir, exhibited reduced efficacy in neuronal cells compared to hepatic cells. These results should be taken into account in the development of direct-acting antivirals for HEV and their potency at extrahepatic replication sites.

Propionic acid promotes neurite recovery in damaged multiple sclerosis neurons.

Neurodegeneration in the autoimmune disease multiple sclerosis still poses a major therapeutic challenge. Effective drugs that target the inflammation can only partially reduce accumulation of neurological deficits and conversion to progressive disease forms. Diet and the associated gut microbiome are currently being discussed as crucial environmental risk factors that determine disease onset and subsequent progression. In people with multiple sclerosis, supplementation of the short-chain fatty acid propionic acid, as a microbial metabolite derived from the fermentation of a high-fiber diet, has previously been shown to regulate inflammation accompanied by neuroprotective properties. We set out to determine whether the neuroprotective impact of propionic acid is a direct mode of action of short-chain fatty acids on CNS neurons. We analysed neurite recovery in the presence of the short-chain fatty acid propionic acid and butyric acid in a reverse-translational disease-in-a-dish model of human-induced primary neurons differentiated from people with multiple sclerosis-derived induced pluripotent stem cells. We found that recovery of damaged neurites is induced by propionic acid and butyric acid. We could also show that administration of butyric acid is able to enhance propionic acid-associated neurite recovery. Whole-cell proteome analysis of induced primary neurons following recovery in the presence of propionic acid revealed abundant changes of protein groups that are associated with the chromatin assembly, translational, and metabolic processes. We further present evidence that these alterations in the chromatin assembly were associated with inhibition of histone deacetylase class I/II following both propionic acid and butyric acid treatment, mediated by free fatty acid receptor signalling. While neurite recovery in the presence of propionic acid is promoted by activation of the anti-oxidative response, administration of butyric acid increases neuronal ATP synthesis in people with multiple sclerosis-specific induced primary neurons.

Proof of infectivity of hepatitis E virus particles from the ejaculate of chronically infected patients.

Recently, hepatitis E virus (HEV, Paslahepevirus balayani) particles were detected for the first time in the ejaculate of two chronically infected patients. Since then, we have been able to detect HEV in ejaculate in five further patients, and thus in a total of seven out of nine (78%) chronically infected men (age 36-67 years, median 56 years). In five patients, the HEV RNA concentration was more than 100-fold higher compared to the serum, while in two patients, the viral load was more than 10-fold lower. However, it has remained unclear whether viral particles shed in the ejaculate were infectious, as a previous cell culture model had failed to demonstrate the infectivity. In the current study, we employed an optimized HEV cell culture system based on overconfluent PLC/PRF/5 cells to investigate the infectivity of HEV particles from ejaculate and other body fluids. With this approach, we were able to show for the first time that HEV particles in the ejaculate from several patients were infectious. HEV replicated to high viral loads of 1e9 HEV RNA copies per ml. This indicates that HEV-positive ejaculate could bear a risk of infection for sexual partners.

Genetic determinants of host- and virus-derived insertions for hepatitis E virus replication.

Hepatitis E virus (HEV) is a long-neglected RNA virus and the major causative agent of acute viral hepatitis in humans. Recent data suggest that HEV has a very heterogeneous hypervariable region (HVR), which can tolerate major genomic rearrangements. In this study, we identify insertions of previously undescribed sequence snippets in serum samples of a ribavirin treatment failure patient. These insertions increase viral replication while not affecting sensitivity towards ribavirin in a subgenomic replicon assay. All insertions contain a predicted nuclear localization sequence and alanine scanning mutagenesis of lysine residues in the HVR influences viral replication. Sequential replacement of lysine residues additionally alters intracellular localization in a fluorescence dye-coupled construct. Furthermore, distinct sequence patterns outside the HVR are identified as viral determinants that recapitulate the enhancing effect. In conclusion, patient-derived insertions can increase HEV replication and synergistically acting viral determinants in and outside the HVR are described. These results will help to understand the underlying principles of viral adaptation by viral- and host-sequence snatching during the clinical course of infection.

Hepatitis E virus infections in German blood donors: results of 8 years of screening, 2015 to 2022.

BackgroundAwareness of transfusion-transmitted hepatitis E raised in recent years led to the mandatory testing of blood donations in some European countries for hepatitis E virus (HEV) RNA. However, little is known about the epidemiology of HEV infections.AimTo and describe and analyse the epidemiology of HEV infections in blood donors in Germany.MethodsData from routine testing of therapeutic blood products donated between January 2015 and December 2022 at the Uni.Blutspendedienst OWL were analysed at the Institute of Laboratory and Transfusion Medicine, Heart and Diabetes Centre North Rhine-Westphalia. A total of 731,630 allogenic blood donations from 119,610 individual blood donors were tested for HEV RNA in minipools of 96 samples. The HEV RNA-positive donations were analysed for the presence of anti-HEV IgM and IgG. The HEV strains were genotyped and various clinical liver-specific parameters were determined.ResultsA total of 497 HEV-positive blood donations were identified, resulting in a yearly incidence of 1:1,474, from which 78.4% of the donations were RNA-only positive. Increased alanine aminotransferase activity was determined in 26.6% of HEV RNA-positive donors and was associated with the detection of IgG antibodies (1.2% anti-HEV IgM-positive, 11.9% anti-HEV IgM- and IgG-positive and 8.5% anti-HEV IgG-positive). An average incidence of 0.084-0.083% HEV RNA-positive donations in June and July in all years was observed, and a higher proportion of HEV RNA-positive men compared with women. All isolated HEV sequences corresponded to genotype 3.ConclusionOur results underline the necessity of HEV RNA screening in blood donations.

Subclinical infection and potential shedding routes of equine parvovirus-hepatitis among hospitalized horses in Austria.

BACKGROUND: Equine parvovirus hepatitis (EqPV-H) can cause Theiler's disease and subclinical hepatitis in horses. OBJECTIVES: Assess the frequency of subclinical EqPV-H infection in hospitalized horses and to study viral transmission by investigating potential shedding routes. ANIMALS: One hundred sixteen equids, that presented to the University Equine Hospital of the University of Veterinary Medicine Vienna between February 2021 and March 2022, for causes other than hepatopathy. METHODS: In this cross-sectional study, samples (serum, feces, nasal, and buccal swabs) of hospitalized horses were collected. Sera were screened for the presence of anti-EqPV-H antibodies by a luciferase immunoprecipitation system assay. Quantitative PCR was used for the detection of EqPV-H DNA in the samples and a nested PCR was used for further validation. RESULTS: Seroprevalence was 10.3% (12/116) and viremia occurred in 12.9% (15/116) of the serologically positive horses. The detected viral load in serum varied from non-quantifiable amount to 1.3 × 106 genome equivalents per milliliter of serum. A low viral load of EqPV-H DNA was detected in 2 nasal swabs and 1 fecal sample. CONCLUSION AND CLINICAL IMPORTANCE: EqPV-H DNA was detected in nasal secretions and feces of viremic horses, which could pose a risk to naive hospitalized horses. It is advisable to screen hospitalized horses that are potential donors of blood or plasma to reduce the risk of iatrogenic EqPV-H transmission.

Inactivation of yellow fever virus by WHO-recommended hand rub formulations and surface disinfectants.

Despite continued outbreaks of yellow fever virus (YFV) in endemic regions, data on its environmental stability or guidelines for its effective inactivation is limited. Here, we evaluated the susceptibility of the YFV 17D vaccine strain to inactivation by ethanol, 2-propanol, World Health Organization (WHO)-recommended hand rub formulations I and II, as well as surface disinfectants. In addition, two pathogenic strains were tested to compare inactivation kinetics by WHO-recommended hand rub formulations I and II. Furthermore, environmental stability of the vaccine strain was assessed. YFV 17D particles displayed infectivity half-life decay profiles of ~13 days at room temperature. Despite this extended environmental stability, YFV was efficiently inactivated by alcohols, WHO-recommended hand formulations, and four out of five tested surface disinfectants. These results are useful in defining disinfection protocols to prevent non-vector borne YFV transmission.

Targeting cellular cathepsins inhibits hepatitis E virus entry.

BACKGROUND AND AIMS: HEV is estimated to be responsible for 70,000 deaths annually, yet therapy options remain limited. In the pursuit of effective antiviral therapies, targeting viral entry holds promise and has proven effective for other viruses. However, the precise mechanisms and host factors required during HEV entry remain unclear. Cellular proteases have emerged as host factors required for viral surface protein activation and productive cell entry by many viruses. Hence, we investigated the functional requirement and therapeutic potential of cellular protease during HEV infection. APPROACH AND RESULTS: Using our established HEV cell culture model and subgenomic HEV replicons, we found that blocking lysosomal cathepsins (CTS) with small molecule inhibitors impedes HEV infection without affecting replication. Most importantly, the pan-cathepsin inhibitor K11777 suppressed HEV infections with an EC 50 of ~0.02 nM. Inhibition by K11777, devoid of notable toxicity in hepatoma cells, was also observed in HepaRG and primary human hepatocytes. Furthermore, through time-of-addition and RNAscope experiments, we confirmed that HEV entry is blocked by inhibition of cathepsins. Cathepsin L (CTSL) knockout cells were less permissive to HEV, suggesting that CTSL is critical for HEV infection. Finally, we observed cleavage of the glycosylated ORF2 protein and virus particles by recombinant CTSL. CONCLUSIONS: In summary, our study highlights the pivotal role of lysosomal cathepsins, especially CTSL, in the HEV entry process. The profound anti-HEV efficacy of the pan-cathepsin inhibitor K11777, especially with its notable safety profile in primary cells, further underscores its potential as a therapeutic candidate.

TMPRSS2-mediated SARS-CoV-2 uptake boosts innate immune activation, enhances cytopathology, and drives convergent virus evolution.

The accessory protease transmembrane protease serine 2 (TMPRSS2) enhances severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) uptake into ACE2-expressing cells, although how increased entry impacts downstream viral and host processes remains unclear. To investigate this in more detail, we performed infection assays in engineered cells promoting ACE2-mediated entry with and without TMPRSS2 coexpression. Electron microscopy and inhibitor experiments indicated TMPRSS2-mediated cell entry was associated with increased virion internalization into endosomes, and partially dependent upon clathrin-mediated endocytosis. TMPRSS2 increased panvariant uptake efficiency and enhanced early rates of virus replication, transcription, and secretion, with variant-specific profiles observed. On the host side, transcriptional profiling confirmed the magnitude of infection-induced antiviral and proinflammatory responses were linked to uptake efficiency, with TMPRSS2-assisted entry boosting early antiviral responses. In addition, TMPRSS2-enhanced infections increased rates of cytopathology, apoptosis, and necrosis and modulated virus secretion kinetics in a variant-specific manner. On the virus side, convergent signatures of cell-uptake-dependent innate immune induction were recorded in viral genomes, manifesting as switches in dominant coupled Nsp3 residues whose frequencies were correlated to the magnitude of the cellular response to infection. Experimentally, we demonstrated that selected Nsp3 mutations conferred enhanced interferon antagonism. More broadly, we show that TMPRSS2 orthologues from evolutionarily diverse mammals facilitate panvariant enhancement of cell uptake. In summary, our study uncovers previously unreported associations, linking cell entry efficiency to innate immune activation kinetics, cell death rates, virus secretion dynamics, and convergent selection of viral mutations. These data expand our understanding of TMPRSS2's role in the SARS-CoV-2 life cycle and confirm its broader significance in zoonotic reservoirs and animal models.

Neuroinvasion and neurotropism of severe acute respiratory syndrome coronavirus 2 infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019, contributes to neurological pathologies in nearly 30% of patients, extending beyond respiratory symptoms. These manifestations encompass disorders of both the peripheral and central nervous systems, causing among others cerebrovascular issues and psychiatric manifestations during the acute and/or post-acute infection phases. Despite ongoing research, uncertainties persist about the precise mechanism the virus uses to infiltrate the central nervous system and the involved entry portals. This review discusses the potential entry routes, including hematogenous and anterograde transport. Furthermore, we explore variations in neurotropism, neurovirulence, and neurological manifestations among pandemic-associated variants of concern. In conclusion, SARS-CoV-2 can infect numerous cells within the peripheral and central nervous system, provoke inflammatory responses, and induce neuropathological changes.

Kinetics of Hepatitis E Virus Infections in Asymptomatic Persons.

To determine the kinetics of hepatitis E virus (HEV) in asymptomatic persons and to evaluate viral load doubling time and half-life, we retrospectively tested samples retained from 32 HEV RNA-positive asymptomatic blood donors in Germany. Close-meshed monitoring of viral load and seroconversion in intervals of ≈4 days provided more information about the kinetics of asymptomatic HEV infections. We determined that a typical median infection began with PCR-detectable viremia at 36 days and a maximum viral load of 2.0 × 104 IU/mL. Viremia doubled in 2.4 days and had a half-life of 1.6 days. HEV IgM started to rise on about day 33 and peaked on day 36; IgG started to rise on about day 32 and peaked on day 53. Although HEV IgG titers remained stable, IgM titers became undetectable in 40% of donors. Knowledge of the dynamics of HEV viremia is useful for assessing the risk for transfusion-transmitted hepatitis E.