News

group leader: Prof. Pietschmann

Recent Submissions

  • Yellow Fever: Integrating Current Knowledge with Technological Innovations to Identify Strategies for Controlling a Re-Emerging Virus.

    Kleinert, Robin D V; Montoya-Diaz, Eduardo; Khera, Tanvi; Welsch, Kathrin; Tegtmeyer, Birthe; Hoehl, Sebastian; Ciesek, Sandra; Brown, Richard J P; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany. (MPDI, 2019-10-17)
    Yellow fever virus (YFV) represents a re-emerging zoonotic pathogen, transmitted by mosquito vectors to humans from primate reservoirs. Sporadic outbreaks of YFV occur in endemic tropical regions, causing a viral hemorrhagic fever (VHF) associated with high mortality rates. Despite a highly effective vaccine, no antiviral treatments currently exist. Therefore, YFV represents a neglected tropical disease and is chronically understudied, with many aspects of YFV biology incompletely defined including host range, host-virus interactions and correlates of host immunity and pathogenicity. In this article, we review the current state of YFV research, focusing on the viral lifecycle, host responses to infection, species tropism and the success and associated limitations of the YFV-17D vaccine. In addition, we highlight the current lack of available treatments and use publicly available sequence and structural data to assess global patterns of YFV sequence diversity and identify potential drug targets. Finally, we discuss how technological advances, including real-time epidemiological monitoring of outbreaks using next-generation sequencing and CRISPR/Cas9 modification of vector species, could be utilized in future battles against this re-emerging pathogen which continues to cause devastating disease
  • Characterization of Equine Parvovirus in Thoroughbred Breeding Horses from Germany.

    Meister, Toni Luise; Tegtmeyer, Birthe; Brüggemann, Yannick; Sieme, Harald; Feige, Karsten; Todt, Daniel; Stang, Alexander; Cavalleri, Jessika-M V; Steinmann, Eike; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany. (MPDI, 2019-10-18)
  • Synthesis of 4′/5′-Spirocyclopropanated Uridine and d -Xylouridine Derivatives and Their Activity against the Human Respiratory Syncytial Virus

    Köllmann, Christoph; Wiechert, Svenja M.; Jones, Peter G.; Pietschmann, Thomas; Werz, Daniel B.; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany. (American Chemical Society, 2019-09-06)
  • Chronic Hepatitis E Virus Infection during Lymphoplasmacytic Lymphoma and Ibrutinib Treatment.

    Schlevogt, Bernhard; Kinast, Volker; Reusch, Julia; Kerkhoff, Andrea; Praditya, Dimas; Todt, Daniel; Schmidt, Hartmut H; Steinmann, Eike; Behrendt, Patrick; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany. (MPDI, 2019-08-22)
    Hepatitis E virus (HEV) is an increasingly recognised pathogen, affecting several hundred thousand individuals in western countries each year. Importantly, the majority of immunocompromised individuals are not able to clear HEV but develop a chronic course of infection. In the case of lymphoma, which is an inherent immunosuppressive disease per se, chemotherapy can even further exacerbate the immunosuppressive status. As the mechanism of HEV chronification is barely understood, it is important to gain knowledge about the influence of chemotherapeutic drugs on the HEV replication cycle to guide rational clinical management of HEV infection in such patients. In this case report, a 70 year old man was diagnosed with lymphoplasmacytic lymphoma. As we observed the occurrence of chronic HEV after treatment with the Bruton's tyrosine kinase (BTK) inhibitor ibrutinib in vivo, we investigated the influence of BTK signaling and ibrutinib treatment in the HEV replication cycle in vitro. First, we detected an HEV-induced mobilisation of BTK in human liver cells during HEV replication. A moderate antiviral effect against HEV replicating isolates including genotypes 1 and 3 was observed, suggesting that ibrutinib did not support HEV replication in a direct manner. Combinatory treatments of ibrutinib with ribavirin indicated that ibrutinib did not influence the antiviral effect of ribavirin. Taken together, chemotherapy targeting cellular factors for the treatment of lymphomas may be a neglected risk factor for the chronification of HEV. For ibrutinib, despite the upregulation of its target BTK during HEV replication, we observed neither a proviral effect on HEV replication nor an influence on the antiviral effect of ribavirin, suggesting that the chronification of HEV may be favoured by its immunosuppressive effect.
  • Chronic equine hepacivirus infection in an adult gelding with severe hepatopathy.

    Tegtmeyer, Birthe; Echelmeyer, Julia; Pfankuche, Vanessa M; Puff, Christina; Todt, Daniel; Fischer, Nicole; Durham, Andy; Feige, Karsten; Baumgärtner, Wolfgang; Steinmann, Eike; et al. (Wiley Open Access, 2019-01-01)
    Background: Equine hepacivirus (EqHV) in equids represents the closest homologue to hepatitis C virus(HCV) infecting humans. A majority of HCV infected patients develop a chronic course of infection leading toliver fibrosis, cirrhosis and liver failure. However, in horses mostly transient mild subclinical infections arereported for EqHV to date. Objectives: EqHV can be involved in chronic liver diseases of horses. Methods:Biochemical parameters in serum samples were measured. Viral load was determined using qPCR. Next gener-ation sequencing (NGS) of serum was performed. Liver tissue was stained with haematoxylin and eosin andanalysed for viral RNA with fluorescentin situ-hybridization. Results: The horse showed symptoms of severehepatopathy and was chronically infected with EqHV. Viral RNA was detectable in the liver during disease.To rule out other infectious agents NGS was performed and showed the highest abundance for EqHV. Theidentified virus sequence was similar to other circulating equine hepaciviruses. Conclusions: EqHV can be asso-ciated with liver disease in horses. Whether it causes the disease or contributes in a multifactorial mannerneeds further investigation
  • Anti-infective Properties of the Golden Spice Curcumin.

    Praditya, Dimas; Kirchhoff, Lisa; Brüning, Janina; Rachmawati, Heni; Steinmann, Joerg; Steinmann, Eike; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany. (Frontiers, 2019-01-01)
    The search for novel anti-infectives is one of the most important challenges in natural product research, as diseases caused by bacteria, viruses, and fungi are influencing the human society all over the world. Natural compounds are a continuing source of novel anti-infectives. Accordingly, curcumin, has been used for centuries in Asian traditional medicine to treat various disorders. Numerous studies have shown that curcumin possesses a wide spectrum of biological and pharmacological properties, acting, for example, as anti-inflammatory, anti-angiogenic and anti-neoplastic, while no toxicity is associated with the compound. Recently, curcumin's antiviral and antibacterial activity was investigated, and it was shown to act against various important human pathogens like the influenza virus, hepatitis C virus, HIV and strains of Staphylococcus, Streptococcus, and Pseudomonas. Despite the potency, curcumin has not yet been approved as a therapeutic antiviral agent. This review summarizes the current knowledge and future perspectives of the antiviral, antibacterial, and antifungal effects of curcumin.
  • Identification of Keratin 23 as a Hepatitis C Virus-Induced Host Factor in the Human Liver.

    Kinast, Volker; Leber, Stefan L; Brown, Richard J P; Vieyres, Gabrielle; Behrendt, Patrick; Eßbach, Constanze; Strnad, Pavel; Vondran, Florian W R; Cornberg, Markus; Wex, Cora; et al. (MPDI, 2019-06-18)
    Keratin proteins form intermediate filaments, which provide structural support for many tissues. Multiple keratin family members are reported to be associated with the progression of liver disease of multiple etiologies. For example, keratin 23 (KRT23) was reported as a stress-inducible protein, whose expression levels correlate with the severity of liver disease. Hepatitis C virus (HCV) is a human pathogen that causes chronic liver diseases including fibrosis, cirrhosis, and hepatocellular carcinoma. However, a link between KRT23 and hepatitis C virus (HCV) infection has not been reported previously. In this study, we investigated KRT23 mRNA levels in datasets from liver biopsies of chronic hepatitis C (CHC) patients and in primary human hepatocytes experimentally infected with HCV, in addition to hepatoma cells. Interestingly, in each of these specimens, we observed an HCV-dependent increase of mRNA levels. Importantly, the KRT23 protein levels in patient plasma decreased upon viral clearance. Ectopic expression of KRT23 enhanced HCV infection; however, CRIPSPR/Cas9-mediated knockout did not show altered replication efficiency. Taken together, our study identifies KRT23 as a novel, virus-induced host-factor for hepatitis C virus.
  • Equine Parvovirus-Hepatitis Frequently Detectable in Commercial Equine Serum Pools.

    Meister, Toni Luise; Tegtmeyer, Birthe; Postel, Alexander; Cavalleri, Jessika-M V; Todt, Daniel; Stang, Alexander; Steinmann, Eike; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany. (MDPI, 2019-05-21)
    An equine parvovirus-hepatitis (EqPV-H) has been recently identified in association with equine serum hepatitis, also known as Theiler's disease. This disease was first described by Arnold Theiler in 1918 and is often observed after applications with blood products in equines. So far, the virus has only been described in the USA and China. In this study, we evaluated the presence of EqPV-H in several commercial serum samples to assess the potential risk of virus transmission by equine serum-based products for medical and research applications. In 11 out of 18 commercial serum samples, EqPV-H DNA was detectable with a viral load up to 105 copies/mL. The same serum batches as well as three additional samples were also positive for antibodies against the EqPV-H VP1 protein. The countries of origin with detectable viral genomes included the USA, Canada, New Zealand, Italy, and Germany, suggesting a worldwide distribution of EqPV-H. Phylogenetic analysis of the EqPV-H NS1 sequence in commercial serum samples revealed high similarities in viral sequences from different geographical areas. As horse sera are commonly used for the production of anti-sera, which are included in human and veterinary medical products, these results implicate the requirement for diagnostic tests to prevent EqPV-H transmission.
  • A central hydrophobic E1 region controls the pH range of hepatitis C virus membrane fusion and susceptibility to fusion inhibitors.

    Banda, Dominic H; Perin, Paula M; Brown, Richard J P; Todt, Daniel; Solodenko, Wladimir; Hoffmeyer, Patrick; Kumar Sahu, Kamlesh; Houghton, Michael; Meuleman, Philip; Müller, Rolf; et al. (Elsevier, 2019-06-01)
  • Antiviral Meroterpenoid Rhodatin and Sesquiterpenoids Rhodocoranes A-E from the Wrinkled Peach Mushroom, Rhodotus palmatus.

    Sandargo, Birthe; Michehl, Maira; Praditya, Dimas; Steinmann, Eike; Stadler, Marc; Surup, Frank; HZI,Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7,38124 Braunschweig, Germany; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany. (American Chemical Society, 2019-05-03)
    Rhodatin (1), a meroterpenoid featuring a unique pentacyclic scaffold with both spiro and spiroketal centers, and five unusual acorane-type sesquiterpenoids, named rhodocoranes A-E (2-6, respectively), are the first natural products isolated from the basidiomycete Rhodotus palmatus. Their structures were elucidated by two-dimensional NMR experiments and HRESIMS, while the absolute configuration of the substance family was determined by Mosher's method utilizing 2. Rhodatin strongly inhibited hepatitis C virus, whereas 4 displayed cytotoxicity and selective antifungal activity.
  • HCV Pit Stop at the Lipid Droplet: Refuel Lipids and Put on a Lipoprotein Coat before Exit.

    Vieyres, Gabrielle; Pietschmann, Thomas; TWINCORE, Zentrum für Experimentelle und klinische Infektionsforschung GmbH, Feodor-Lynen-Str. 7, 30625 Hannover, Germany. (MPDI, 2019-03-12)
    The replication cycle of the liver-tropic hepatitis C virus (HCV) is tightly connected to the host lipid metabolism, during the virus entry, replication, assembly and egress stages, but also while the virus circulates in the bloodstream. This interplay coins viral particle properties, governs viral cell tropism, and facilitates immune evasion. This review summarizes our knowledge of these interactions focusing on the late steps of the virus replication cycle. It builds on our understanding of the cell biology of lipid droplets and the biosynthesis of liver lipoproteins and attempts to explain how HCV hijacks these organelles and pathways to assemble its lipo-viro-particles. In particular, this review describes (i) the mechanisms of viral protein translocation to and from the lipid droplet surface and the orchestration of an interface between replication and assembly complexes, (ii) the importance of the triglyceride mobilization from the lipid droplets for HCV assembly, (iii) the interplay between HCV and the lipoprotein synthesis pathway including the role played by apolipoproteins in virion assembly, and finally (iv) the consequences of these complex virus–host interactions on the virion composition and its biophysical properties. The wealth of data accumulated in the past years on the role of the lipid metabolism in HCV assembly and its imprint on the virion properties will guide vaccine design efforts and reinforce our understanding of the hepatic lipid metabolism in health and disease.
  • Hepatitis C Virus Strain-Dependent Usage of Apolipoprotein E Modulates Assembly Efficiency and Specific Infectivity of Secreted Virions.

    Weller, Romy; Hueging, Kathrin; Brown, Richard J P; Todt, Daniel; Joecks, Sebastian; Vondran, Florian W R; Pietschmann, Thomas; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH, Feodor-Lynen-Str.7,30625 Hannover, Germany. (American Society for Microbiology, 2017-09-15)
    Hepatitis C virus (HCV) is extraordinarily diverse and uses entry factors in a strain-specific manner. Virus particles associate with lipoproteins, and apolipoprotein E (ApoE) is critical for HCV assembly and infectivity. However, whether ApoE dependency is common to all HCV genotypes remains unknown. Therefore, we compared the roles of ApoE utilizing 10 virus strains from genotypes 1 through 7. ApoA and ApoC also support HCV assembly, so they may contribute to virus production in a strain-dependent fashion. Transcriptome sequencing (RNA-seq) revealed abundant coexpression of ApoE, ApoB, ApoA1, ApoA2, ApoC1, ApoC2, and ApoC3 in primary hepatocytes and in Huh-7.5 cells. Virus production was examined in Huh-7.5 cells with and without ApoE expression and in 293T cells where individual apolipoproteins (ApoE1, -E2, -E3, -A1, -A2, -C1, and -C3) were provided in trans All strains were strictly ApoE dependent. However, ApoE involvement in virus production was strain and cell type specific, because some HCV strains poorly produced infectious virus in ApoE-expressing 293T cells and because ApoE knockout differentially affected virus production of HCV strains in Huh-7.5 cells. ApoE allelic isoforms (ApoE2, -E3, and -E4) complemented virus production of HCV strains to comparable degrees. All tested strains assembled infectious progeny with ApoE in preference to other exchangeable apolipoproteins (ApoA1, -A2, -C1, and -C3). The specific infectivity of HCV particles was similar for 293T- and Huh-7.5-derived particles for most strains; however, it differed by more than 100-fold in some viruses. Collectively, this study reveals strain-dependent and host cell-dependent use of ApoE during HCV assembly. These differences relate to the efficacy of virus production and also to the properties of released virus particles and therefore govern viral fitness at the level of assembly and cell entry.IMPORTANCE Chronic HCV infections are a major cause of liver disease. HCV is highly variable, and strain-specific determinants modulate the response to antiviral therapy, the natural course of infection, and cell entry factor usage. Here we explored whether host factor dependency of HCV in particle assembly is modulated by strain-dependent viral properties. We showed that all examined HCV strains, which represent all seven known genotypes, rely on ApoE expression for assembly of infectious progeny. However, the degree of ApoE dependence is modulated in a strain-specific and cell type-dependent manner. This indicates that HCV strains differ in their assembly properties and host factor usage during assembly of infectious progeny. Importantly, these differences relate not only to the efficiency of virus production and release but also to the infectiousness of virus particles. Thus, strain-dependent features of HCV modulate ApoE usage, with implications for virus fitness at the level of assembly and cell entry.
  • Physicochemical Properties Govern the Activity of Potent Antiviral Flavones

    Martin-Benlloch, Xavier; Haid, Sybille; Novodomska, Alexandra; Rominger, Frank; Pietschmann, Thomas; Davioud-Charvet, Elisabeth; Elhabiri, Mourad; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH, Feodor-Lynen-Str.7,30625 Hannover, Germany. (American Chemical Society, 2019-03-05)
    Ladanein (i.e., 5,6,7-trihydroxylated flavone) was demonstrated to act as a powerful virucidal agent toward a broad range of enveloped virus particles. Fe(III) coordination and pH are indeed among the key parameters that might favor both bioactivation of the flavone and consequent host cell entry inhibition. In this present work, the impact of fluorinated groups on the physicochemical and antiviral properties of the flavone was investigated, thus allowing a deeper understanding of the antiviral mode of action. The improved synthesis of ladanein allowed accessing a broad range of analogues, some of them being significantly more active than the former ladanein lead compound. We first determined the acido-basic properties of this homogenous series of compounds and then investigated their electrochemical behavior. Fe(III) coordination properties (stability, spectral behavior, and kinetics) of ladanein and its analogues were then examined (quasiphysiological conditions) and provided key information of their stability and reactivity. Using the determined physicochemical parameters, the critical impact of the iron complexation and medium acidity was confirmed on hepatitis C virus (HCV) particles (pre)treated with ladanein. Finally, a preliminary structure–HCV entry inhibition relationship study evidenced the superior antiviral activity of the ladanein analogues bearing an electron-withdrawing group in para position (FCF3 > FOCF3 > FFCF3 > FF > FOMe) on the B cycle in comparison with the parent ladanein itself.
  • Influence of Tattoo Ink on Hepatitis C Virus Infectiousness.

    Behrendt, Patrick; Brüning, Janina; Todt, Daniel; Steinmann, Eike; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH, Feodor-Lynen-Str.7,30625 Hannover, Germany. (Oxford Academic, 2019-03-01)
    Hepatitis C virus (HCV) is a blood-borne virus and is most frequently transmitted through large or repeated direct percutaneous exposures to infected blood. The 2 most common exposures associated with transmission of HCV are blood transfusion and intravenous drug abuse. The association between HCV transmission and other suspected risk factors such as tattooing is more controversial. Although HCV can survive for days to weeks in suspension or on inanimate surfaces, its stability in tattooing supplies remains elusive. Here, we analyzed the influence of tattoo ink on HCV infectiousness.
  • Hepatitis C Virus.

    Pietschmann, Thomas; Brown, Richard J P; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany. (Elsevier, 2019-01-29)
    Hepatitis C virus (HCV) is an enveloped, RNA virus transmitted through blood-to-blood contact. It infects humans only and primarily targets liver cells. HCV evades innate and adaptive immunity and establishes chronic infections in 70% of cases. If untreated, 20% of patients develop liver cirrhosis, and a fraction of these progress to hepatocellular carcinoma. Annually, 400000 patients die globally due to HCV infection. Direct-acting antivirals (DAAs) are licensed and target three viral proteins: the NS3-4A protease needed for processing the viral polyprotein, the NS5A phosphoprotein that regulates RNA replication and virus assembly, and the viral RNA-dependent RNA polymerase (NS5B) that catalyzes genome replication. Combination therapies cure more than 95% of treated patients. Approximately 71 million people are chronically infected and 1.7 million new infections occur annually. Treatment-induced cure does not protect from viral reinfection. A prophylactic vaccine is under development.
  • Conformational Flexibility in the Immunoglobulin-Like Domain of the Hepatitis C Virus Glycoprotein E2.

    Vasiliauskaite, Ieva; Owsianka, Ania; England, Patrick; Khan, Abdul Ghafoor; Cole, Sarah; Bankwitz, Dorothea; Foung, Steven K H; Pietschmann, Thomas; Marcotrigiano, Joseph; Rey, Felix A; et al. (ASM, 2017-05-16)
    The hepatitis C virus (HCV) glycoprotein E2 is the major target of neutralizing antibodies and is therefore highly relevant for vaccine design. Its structure features a central immunoglobulin (Ig)-like β-sandwich that contributes to the binding site for the cellular receptor CD81. We show that a synthetic peptide corresponding to a β-strand of this Ig-like domain forms an α-helix in complex with the anti-E2 antibody DAO5, demonstrating an inside-out flip of hydrophobic residues and a secondary structure change in the composite CD81 binding site. A detailed interaction analysis of DAO5 and cross-competing neutralizing antibodies with soluble E2 revealed that the Ig-like domain is trapped by different antibodies in at least two distinct conformations. DAO5 specifically captures retrovirus particles bearing HCV glycoproteins (HCVpp) and infectious cell culture-derived HCV particles (HCVcc). Infection of cells by DAO5-captured HCVpp can be blocked by a cross-competing neutralizing antibody, indicating that a single virus particle simultaneously displays E2 molecules in more than one conformation on its surface. Such conformational plasticity of the HCV E2 receptor binding site has important implications for immunogen design.
  • Kaposi's Sarcoma-Associated Herpesvirus Nonstructural Membrane Protein pK15 Recruits the Class II Phosphatidylinositol 3-Kinase PI3K-C2α To Activate Productive Viral Replication.

    Abere, Bizunesh; Samarina, Naira; Gramolelli, Silvia; Rückert, Jessica; Gerold, Gisa; Pich, Andreas; Schulz, Thomas F; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany. (2018-09-01)
    Kaposi's sarcoma (KS)-associated herpesvirus (KSHV)/human herpesvirus 8 (HHV-8) causes the angiogenic tumor KS and two B-cell malignancies. The KSHV nonstructural membrane protein encoded by the open reading frame (ORF) K15 recruits and activates several cellular proteins, including phospholipase Cγ1 (PLCγ1), components of the NF-κB pathway, as well as members of the Src family of nonreceptor tyrosine kinases, and thereby plays an important role in the activation of angiogenic and inflammatory pathways that contribute to the pathogenesis of KS as well as KSHV productive (lytic) replication. In order to identify novel cellular components involved in the biology of pK15, we immunoprecipitated pK15 from KSHV-infected endothelial cells and identified associated proteins by label-free quantitative mass spectrometry. Cellular proteins interacting with pK15 point to previously unappreciated cellular processes, such as the endocytic pathway, that could be involved in the function of pK15. We found that the class II phosphatidylinositol 3-kinase (PI3K) PI3K-C2α, which is involved in the endocytosis of activated receptor tyrosine kinases and their signaling from intracellular organelles, interacts and colocalizes with pK15 in vesicular structures abundant in the perinuclear area. Further functional analysis revealed that PI3K-C2α contributes to the pK15-dependent phosphorylation of PLCγ1 and Erk1/2. PI3K-C2α also plays a role in KSHV lytic replication, as evidenced by the reduced expression of the viral lytic genes K-bZIP and ORF45 as well as the reduced release of infectious virus in PI3K-C2α-depleted KSHV-infected endothelial cells. Taken together, our results suggest a role of the cellular PI3K-C2α protein in the functional properties of the KSHV pK15 protein.
  • The Small-Compound Inhibitor K22 Displays Broad Antiviral Activity against Different Members of the Family Flaviviridae and Offers Potential as a Panviral Inhibitor.

    García-Nicolás, Obdulio; V'kovski, Philip; Vielle, Nathalie J; Ebert, Nadine; Züst, Roland; Portmann, Jasmine; Stalder, Hanspeter; Gaschen, Véronique; Vieyres, Gabrielle; Stoffel, Michael; et al. (2018-11-01)
    The virus family
  • The natural compound silvestrol inhibits hepatitis E virus (HEV) replication in vitro and in vivo.

    Todt, Daniel; Moeller, Nora; Praditya, Dimas; Kinast, Volker; Friesland, Martina; Engelmann, Michael; Verhoye, Lieven; Sayed, Ibrahim M; Behrendt, Patrick; Dao Thi, Viet Loan; et al. (2018-09-01)
    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.
  • Hepatitis C virus enters liver cells using the CD81 receptor complex proteins calpain-5 and CBLB.

    Bruening, Janina; Lasswitz, Lisa; Banse, Pia; Kahl, Sina; Marinach, Carine; Vondran, Florian W; Kaderali, Lars; Silvie, Olivier; Pietschmann, Thomas; Meissner, Felix; et al. (2018-07-01)
    Hepatitis C virus (HCV) and the malaria parasite Plasmodium use the membrane protein CD81 to invade human liver cells. Here we mapped 33 host protein interactions of CD81 in primary human liver and hepatoma cells using high-resolution quantitative proteomics. In the CD81 protein network, we identified five proteins which are HCV entry factors or facilitators including epidermal growth factor receptor (EGFR). Notably, we discovered calpain-5 (CAPN5) and the ubiquitin ligase Casitas B-lineage lymphoma proto-oncogene B (CBLB) to form a complex with CD81 and support HCV entry. CAPN5 and CBLB were required for a post-binding and pre-replication step in the HCV life cycle. Knockout of CAPN5 and CBLB reduced susceptibility to all tested HCV genotypes, but not to other enveloped viruses such as vesicular stomatitis virus and human coronavirus. Furthermore, Plasmodium sporozoites relied on a distinct set of CD81 interaction partners for liver cell entry. Our findings reveal a comprehensive CD81 network in human liver cells and show that HCV and Plasmodium highjack selective CD81 interactions, including CAPN5 and CBLB for HCV, to invade cells.

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