Michael Engelmann

Extra-hepatic replication and infection of hepatitis E virus in neuronal-derived cells

Hepatitis E virus (HEV) is the causative agent of hepatitis E in humans and a member of the genus Orthohepevirus in the family Hepeviridae. Infection usually leads to acute hepatitis that can become fulminant, particularly among pregnant women and in patients with preexisting liver disease, or may evolve to a chronic state, especially in immunosuppressed individuals. HEV has been shown to produce a range of extra‐hepatic manifestations including aplastic anaemia, acute thyroiditis, glomerulonephritis as well as neurological disorders such as Guillain‐Barré syndrome, neuralgic amyotrophy and encephalitis. The pathogenesis of these neurological injuries remains largely unknown, and it is also uncertain whether or not HEV can directly infect neuronal cells. In this study, we investigated whether HEV is capable of completing the viral life cycle in human neuronal‐derived cell lines such as neuroepithelioma (SK‐N‐MC), desmoplastic cerebellar medulloblastoma (DAOY), glioblastoma multiforme (DBTRG), glioblastoma astrocytoma (U‐373 MG) and oligodendrocytic (M03.13) cells. Following transfection of these cells with HEV Gaussia luciferase reporter virus, all tested cell lines supported HEV RNA replication. Furthermore, extra‐ and intracellular viral capsid was detected by an HEV antigen ELISA as a marker for virus assembly and release. Permissiveness for HEV cell entry could be demonstrated for the oligodendrocytic cell line M03.13. In conclusion, these results indicate that HEV tropism is not restricted to the liver and HEV can potentially complete the full viral life cycle in neuronal‐derived tissues explaining neurologic disorders during HEV infection.

Antiviral Activities of Different Interferon Types and Subtypes against Hepatitis E Virus Replication

ABSTRACT Hepatitis E virus (HEV) is the causative agent of hepatitis E in humans and a member of the genus Orthohepevirus in the family Hepeviridae. HEV infections are the common cause of acute hepatitis but can also take chronic courses. Ribavirin is the treatment of choice for most patients, and type I interferon (IFN) has been evaluated in a few infected transplant patients in vivo. In this study, the antiviral effects of different exogenously administered interferons were investigated by using state-of-the-art subgenomic replicon and full-length HEV genome cell culture models. Hepatitis C virus (HCV) subgenomic replicons based on the genotype 2a JFH1 isolate served as the reference. The experiments revealed that HEV RNA replication was inhibited by the application of all types of IFN, including IFN-α (type I), IFN-γ (type II), and IFN-λ3 (type III), but to a far lesser extent than HCV replication. Simultaneous determination of interferon-stimulated gene (ISG) expression levels for all IFN types demonstrated efficient downregulation by HEV. Furthermore, different IFN-α subtypes were also able to block viral replication in combination with ribavirin. The IFN-α subtypes 2a and 2b exerted the strongest antiviral activity against HEV. In conclusion, these data demonstrate for the first time moderate anti-HEV activities of types II and III IFNs and different IFN-α subtypes. As HEV employed a potent anti-interferon mechanism by restricting ISG expression, exogenous application of IFNs as immunotherapy should be carefully assessed.

Interferon-inducible cholesterol-25-hydroxylase restricts hepatitis C virus replication through blockage of membranous web formation.

Hepatitis C virus (HCV) is a positive‐strand RNA virus that primarily infects human hepatocytes. Infections with HCV constitute a global health problem, with 180 million people currently chronically infected. Recent studies have reported that cholesterol 25‐hydroxylase (CH25H) is expressed as an interferon‐stimulated gene and mediates antiviral activities against different enveloped viruses through the production of 25‐hydroxycholesterol (25HC). However, the intrinsic regulation of human CH25H (hCH25H) expression within the liver as well as its mechanistic effects on HCV infectivity remain elusive. In this study, we characterized the expression of hCH25H using liver biopsies and primary human hepatocytes. In addition, the antiviral properties of this protein and its enzymatic product, 25HC, were further characterized against HCV in tissue culture. Levels of hCH25H messenger RNA were significantly up‐regulated both in HCV‐positive liver biopsies and in HCV‐infected primary human hepatocytes. The expression of hCH25H in primary human hepatocytes was primarily and transiently induced by type I interferon. Transient expression of hCH25H in human hepatoma cells restricted HCV infection in a genotype‐independent manner. This inhibition required the enzymatic activity of CH25H. We observed an inhibition of viral membrane fusion during the entry process by 25HC, which was not due to a virucidal effect. Yet the primary effect by 25HC on HCV was at the level of RNA replication, which was observed using subgenomic replicons of two different genotypes. Further analysis using electron microscopy revealed that 25HC inhibited formation of the membranous web, the HCV replication factory, independent of RNA replication. Conclusion: Infection with HCV causes up‐regulation of interferon‐inducible CH25H in vivo, and its product, 25HC, restricts HCV primarily at the level of RNA replication by preventing formation of the viral replication factory. (Hepatology 2015;62:702–714)

Assessment of cross-species transmission of hepatitis C virus-related non-primate hepacivirus in a population of humans at high risk of exposure.

The recent discovery of hepatitis C virus (HCV)-related viruses in different animal species has raised new speculations regarding the origin of HCV and the possibility of a zoonotic source responsible for the endemic HCV transmission. As a consequence, these new findings prompt questions regarding the potential for cross-species transmissions of hepaciviruses. The closest relatives to HCV discovered to date are the non-primate hepaciviruses (NPHVs), which have been described to infect horses. To evaluate the risk of a potential zoonotic transmission, we analysed NPHV RNA and antibodies in humans with occupational exposure to horses in comparison with a low-risk group. Both groups were negative for NPHV RNA, even though low seroreactivities against various NPHV antigens could be detected irrespective of the group. In conclusion, we did not observe evidence of NPHV transmission between horses and humans.

Frequent detection of HCV RNA and HCVcoreAg in stool of patients with chronic hepatitis C

BACKGROUND AND OBJECTIVE HCV is transmitted mainly by parenteral routes. However, unprotected anal intercourse has also been identified as a risk factor for HCV infection. HCV RNA can be detected in blood, saliva, and bile, but the presence of HCV in stool has not been investigated yet. STUDY DESIGN Therefore, stool samples of 98 patients were collected prospectively. Specific HCV primers were used to identify samples positive for HCV RNA. HCV RNA-positive samples were tested for HCVcoreAg with the Architect HCVAg assay (Abbott). Presence of occult blood was investigated by the hemoCARE guajak test. Viral stability and infectivity of recombinant HCV particles was investigated in vitro by incubation of genotype 2a chimeric virus Jc1 with bile and stool suspensions. RESULTS HCV RNA could be detected in 68 out of 98 stool samples from patients with chronic hepatitis C and 16 samples also tested positive for HCVcoreAg. Presence of HCV RNA in stool was more frequent in male than in female and in patients with low platelet counts but was not associated with the detection of occult blood. Stool suspensions and to a lesser extent bile reduced the in vitro infectivity of genotype 2a chimeric Jc1 virus even though infection of Huh7 cells was not completely abrogated. CONCLUSIONS In summary, this study shows for the first time that HCV can frequently be detected in stool samples of chronically infected patients irrespective of occult bleeding. We suggest that stool can be a potential source for HCV infection and thus unprotected anal intercourse should be avoided.

Virucidal Activity of World Health Organization–Recommended Formulations Against Enveloped Viruses, Including Zika, Ebola, and Emerging Coronaviruses

Abstract The World Health Organization (WHO) published 2 alcohol-based formulations to be used in healthcare settings and for outbreak-associated infections, but inactivation efficacies of these products have not been determined against (re-)emerging viruses. In this study, we evaluated the virucidal activity of these WHO products in a comparative analysis. Zika virus (ZIKV), Ebola virus (EBOV), severe acute respiratory syndrome coronavirus (SARS-CoV), and Middle East respiratory syndrome coronavirus (MERS-CoV) as (re-)emerging viral pathogens and other enveloped viruses could be efficiently inactivated by both WHO formulations, implicating their use in healthcare systems and viral outbreak situations.The World Health Organization (WHO) published 2 alcohol-based formulations to be used in healthcare settings and for outbreak-associated infections, but inactivation efficacies of these products have not been determined against (re-)emerging viruses. In this study, we evaluated the virucidal activity of these WHO products in a comparative analysis. Zika virus (ZIKV), Ebola virus (EBOV), severe acute respiratory syndrome coronavirus (SARS-CoV), and Middle East respiratory syndrome coronavirus (MERS-CoV) as (re-)emerging viral pathogens and other enveloped viruses could be efficiently inactivated by both WHO formulations, implicating their use in healthcare systems and viral outbreak situations.

Apolipoprotein E polymorphisms and their protective effect on hepatitis E virus replication.

We sincerely thank Marot and coworkers for their letter. We agree with them and their meta-analysis concluding that self-expanding metal stents provide an effective alternative to balloon tamponade in selected patients with acute variceal bleeding (AVB), in whom esophageal stent can be used as a bridge to rescue therapies (mainly transjugular intrahepatic portosystemic shunt). Our primary endpoint was to compare the efficacy and safety of the two devices in AVB from esophageal varices refractory to medical and endoscopic therapy, which is the only accepted setting for the use of balloon tamponade (massive AVB or AVB uncontrolled by standard treatment). Being an accepted treatment, for ethical reasons we could not omit the use of esophageal balloon tamponade as a comparator, just to have a perfect control with regard to efficacy. We differ from Marot et al. on their appreciation of the applicability of our results. In real life, we will also treat with stents patients with previous/malpositioned esophageal balloon tamponade (who were not allowed in the trial as this would have precluded obtaining conclusive results on adverse events). In fact, if we had included the 23 patients excluded due to previous balloon tamponade, our initially planned sample size would have been achieved and even exceeded. Moreover, patients with known hepatocellular carcinoma were not excluded from receiving esophageal stents in our current practice but were excluded in the randomized study because of its potential impact on mortality. However, the remaining exclusion criteria were unavoidable when using balloon tamponade. As our study confirms the data from observational studies suggesting that esophageal stents are effective and acceptably safe in refractory AVB, it may be proposed that these might be used in other settings in the context of clinical trials, for instance, in the initial therapy of AVB, where esophageal stents may be compared to standard accepted therapy (combination of vasoactive drugs and endoscopic therapy); however, this would be a completely different study. We do not think that retrospective observational studies from small series with different and heterogeneous entry criteria may provide valid data with regard to comparative efficacy and side effects of these two treatments in this setting either.

Hepatitis E virus replication and interferon responses in human placental cells

Hepatitis E virus (HEV) is a member of the genus Orthohepevirus in the family Hepeviridae and the causative agent of hepatitis E in humans. HEV is a major health problem in developing countries, causing mortality rates up to 25% in pregnant women. However, these cases are mainly reported for HEV genotype (gt)1, while gt3 infections are usually associated with subclinical courses of disease. The pathogenic mechanisms of adverse maternal and fetal outcome during pregnancy in HEV‐infected pregnant women remain elusive. In this study, we observed that HEV is capable of completing the full viral life cycle in placental‐derived cells (JEG‐3). Following transfection of JEG‐3 cells, HEV replication of both HEV gts could be observed. Furthermore, determination of extracellular and intracellular viral capsid levels, infectivity, and biophysical properties revealed production of HEV infectious particles with similar characteristics as in liver‐derived cells. Viral entry was analyzed by infection of target cells and detection of either viral RNA or staining for viral capsid protein by immunofluorescence. HEV gt1 and gt3 were efficiently inhibited by ribavirin in placental as well as in human hepatoma cells. In contrast, interferon‐α sensitivity was lower in the placental cells compared to liver cells for gt1 but not gt3 HEV. Simultaneous determination of interferon‐stimulated gene expression levels demonstrated an efficient HEV‐dependent restriction in JEG‐3. Conclusion: We showed differential tissue‐specific host responses to HEV genotypes, adding to our understanding of the mechanisms contributing to fatal outcomes of HEV infections during pregnancy. Using this cell‐culture system, new therapeutic options for HEV during pregnancy can be identified and evaluated. (Hepatology Communications 2018;2:173–187)

The natural compound silvestrol inhibits hepatitis E virus (HEV) replication in vitro and in vivo.

ABSTRACT Hepatitis E virus (HEV) is the causative agent of hepatitis E in humans and a member of the genus Orthohepevirus in the family Hepeviridae. HEV infections are the common cause of acute hepatitis but can also take chronic courses. Ribavirin is the treatment of choice for most patients and type I interferon (IFN) has been evaluated in a few infected transplantation patients in vivo. However, no effective and specific treatments against HEV infections are currently available. In this study, we evaluated the natural compound silvestrol, isolated from the plant Aglaia foveolata, and known for its specific inhibition of the DEAD‐box RNA helicase eIF4A in state‐of‐the‐art HEV experimental model systems. Silvestrol blocked HEV replication of different subgenomic replicons in a dose‐dependent manner at low nanomolar concentrations and acted additive to ribavirin (RBV). In addition, HEV p6‐based full length replication and production of infectious particles was reduced in the presence of silvestrol. A pangenotypic effect of the compound was further demonstrated with primary isolates from four different human genotypes in HEV infection experiments of hepatocyte‐like cells derived from human embryonic and induced pluripotent stem cells. In vivo, HEV RNA levels rapidly declined in the feces of treated mice while no effect was observed in the vehicle treated control animals. In conclusion, silvestrol could be identified as pangenotypic HEV replication inhibitor in vitro with additive effect to RBV and further demonstrated high potency in vivo. The compound therefore may be considered in future treatment strategies of chronic hepatitis E in immunocompromised patients. HighlightsThe natural compound silvestrol is a potent inhibitor of HEV replication.HEV infection of laboratory and primary isolates could be inhibited by silvestrol.Silvestrol demonstrated high potency in human liver chimeric mice.Targeting translation initiation could be a novel antiviral strategy for the treatment of chronic hepatitis E.

Inactivation of HCV and HIV by microwave: a novel approach for prevention of virus transmission among people who inject drugs

Hepatitis C virus (HCV) and human immunodeficiency virus (HIV-1) transmissions among people who inject drugs (PWID) continue to pose a challenging global health problem. Here, we aimed to analyse a universally applicable inactivation procedure, namely microwave irradiation, as a safe and effective method to reduce the risk of viral transmission. The exposure of HCV from different genotypes to microwave irradiation resulted in a significant reduction of viral infectivity. Furthermore, microwave irradiation reduced viral infectivity of HIV-1 and of HCV/HIV-1 suspensions indicating that this inactivation may be effective at preventing co-infections. To translate microwave irradiation as prevention method to used drug preparation equipment, we could further show that HCV as well as HIV-1 infectivity could be abrogated in syringes and filters. This study demonstrates the power of microwave irradiation for the reduction of viral transmission and establishment of this safety strategy could help reduce the transmission of blood-borne viruses.