• Acute and chronic infections with nonprimate hepacivirus in young horses.

      Gather, Theresa; Walter, Stephanie; Pfaender, Stephanie; Todt, Daniel; Feige, Karsten; Steinmann, Eike; Cavalleri, Jessika M V; Twincore Centre of Experimental and Clinical Infection Research; a joint venture between the Hannover Medical School and the Helmholtz Centre for Infection Research, Hannover 30625, Germany. (2016-09-22)
      The recently discovered nonprimate hepacivirus (NPHV) naturally infects horses and is the closest known homolog of hepatitis C virus to date. Within a follow-up study acute field infections were monitored in four young Thoroughbred horses until the ages of 12-13 months. Serum samples were analyzed for the presence of NPHV RNA and anti-NPHV NS3 antibodies and liver specific parameters were evaluated. The four young horses were not able to clear infection, but remained chronically infected for the entire monitored time period despite the presence of NPHV specific antibodies.
    • Apolipoprotein E polymorphisms and their protective effect on hepatitis E virus replication.

      Weller, Romy; Todt, Daniel; Engelmann, Michael; Friesland, Martina; Wedemeyer, Heiner; Pietschmann, Thomas; Steinmann, Eike; Twincore Centre of Experimental and Clinical Infection Research; a joint venture between the Hannover Medical School and the Helmholtz Centre for Infection Research, Hannover 30625, Germany. (2016-12)
    • Assessment of cross-species transmission of hepatitis C virus-related non-primate hepacivirus in a population of humans at high risk of exposure.

      Pfaender, Stephanie; Walter, Stephanie; Todt, Daniel; Behrendt, Patrick; Doerrbecker, Juliane; Wölk, Benno; Engelmann, Michael; Gravemann, Ute; Seltsam, Axel; Steinmann, Joerg; Burbelo, Peter D; Klawonn, Frank; Feige, Karsten; Pietschmann, Thomas; Cavalleri, Jessika-M V; Steinmann, Eike; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH, Feodor-Lynen-Str. 7, 30625 Hannover, Germany. (2015-09)
      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.
    • Biofilm formation of the black yeast-like fungus Exophiala dermatitidis and its susceptibility to antiinfective agents.

      Kirchhoff, Lisa; Olsowski, Maike; Zilmans, Katrin; Dittmer, Silke; Haase, Gerhard; Sedlacek, Ludwig; Steinmann, Eike; Buer, Jan; Rath, Peter-Michael; Steinmann, Joerg; Twincore Centre of Experimental and Clinical Infection Research; a joint venture between the Hannover Medical School and the Helmholtz Centre for Infection Research, Hannover 30625, Germany. (2017-02-17)
      Various fungi have the ability to colonize surfaces and to form biofilms. Fungal biofilm-associated infections are frequently refractory to targeted treatment because of resistance to antifungal drugs. One fungus that frequently colonises the respiratory tract of cystic fibrosis (CF) patients is the opportunistic black yeast-like fungus Exophiala dermatitidis. We investigated the biofilm-forming ability of E. dermatitidis and its susceptibility to various antiinfective agents and natural compounds. We tested 58 E. dermatitidis isolates with a biofilm assay based on crystal violet staining. In addition, we used three isolates to examine the antibiofilm activity of voriconazole, micafungin, colistin, farnesol, and the plant derivatives 1,2,3,4,6-penta-O-galloyl-b-D-glucopyranose (PGG) and epigallocatechin-3-gallate (EGCG) with an XTT reduction assay. We analysed the effect of the agents on cell to surface adhesion, biofilm formation, and the mature biofilm. The biofilms were also investigated by confocal laser scan microscopy. We found that E. dermatitidis builds biofilm in a strain-specific manner. Invasive E. dermatitidis isolates form most biomass in biofilm. The antiinfective agents and the natural compounds exhibited poor antibiofilm activity. The greatest impact of the compounds was detected when they were added prior cell adhesion. These findings suggest that prevention may be more effective than treatment of biofilm-associated E. dermatitidis infections.
    • Development and virucidal activity of a novel alcohol-based hand disinfectant supplemented with urea and citric acid.

      Ionidis, Georgios; Hübscher, Judith; Jack, Thomas; Becker, Britta; Bischoff, Birte; Todt, Daniel; Hodasa, Veronika; Brill, Florian H H; Steinmann, Eike; Steinmann, Jochen; TWINCORE Centre for Experimental and Clinical Infection Research, Feodor-Lynen-Str. 7, 30625, Hannover, Germany. (2016)
      Hand disinfectants are important for the prevention of virus transmission in the health care system and environment. The development of broad antiviral spectrum hand disinfectants with activity against enveloped and non-enveloped viruses is limited due to a small number of permissible active ingredients able to inactivate viruses.
    • Differential Infection Patterns and Recent Evolutionary Origins of Equine Hepaciviruses in Donkeys.

      Walter, Stephanie; Rasche, Andrea; Moreira-Soto, Andrés; Pfaender, Stephanie; Bletsa, Magda; Corman, Victor Max; Aguilar-Setien, Alvaro; García-Lacy, Fernando; Hans, Aymeric; Todt, Daniel; Schuler, Gerhard; Shnaiderman-Torban, Anat; Steinman, Amir; Roncoroni, Cristina; Veneziano, Vincenzo; Rusenova, Nikolina; Sandev, Nikolay; Rusenov, Anton; Zapryanova, Dimitrinka; García-Bocanegra, Ignacio; Jores, Joerg; Carluccio, Augusto; Veronesi, Maria Cristina; Cavalleri, Jessika M V; Drosten, Christian; Lemey, Philippe; Steinmann, Eike; Drexler, Jan Felix; TwinCore, Zentrum für experimentelle und klinische Infektionsforschung GmbH, Feodor-Lynen-Str.7, 30625 Hannover, Germany. (2017-01-01)
      The hepatitis C virus (HCV) is a major human pathogen. Genetically related viruses in animals suggest a zoonotic origin of HCV. The closest relative of HCV is found in horses (termed equine hepacivirus [EqHV]). However, low EqHV genetic diversity implies relatively recent acquisition of EqHV by horses, making a derivation of HCV from EqHV unlikely. To unravel the EqHV evolutionary history within equid sister species, we analyzed 829 donkeys and 53 mules sampled in nine European, Asian, African, and American countries by molecular and serologic tools for EqHV infection. Antibodies were found in 278 animals (31.5%), and viral RNA was found in 3 animals (0.3%), all of which were simultaneously seropositive. A low RNA prevalence in spite of high seroprevalence suggests a predominance of acute infection, a possible difference from the mostly chronic hepacivirus infection pattern seen in horses and humans. Limitation of transmission due to short courses of infection may explain the existence of entirely seronegative groups of animals. Donkey and horse EqHV strains were paraphyletic and 97.5 to 98.2% identical in their translated polyprotein sequences, making virus/host cospeciation unlikely. Evolutionary reconstructions supported host switches of EqHV between horses and donkeys without the involvement of adaptive evolution. Global admixture of donkey and horse hepaciviruses was compatible with anthropogenic alterations of EqHV ecology. In summary, our findings do not support EqHV as the origin of the significantly more diversified HCV. Identification of a host system with predominantly acute hepacivirus infection may enable new insights into the chronic infection pattern associated with HCV.
    • Echinocandin resistance and population structure of invasive Candida glabrata isolates from two university hospitals in Germany and Austria.

      Klotz, Ulrike; Schmidt, Dirk; Willinger, Birgit; Steinmann, Eike; Buer, Jan; Rath, Peter-Michael; Steinmann, Joerg; Twincore Centre for Experimental and Clinical Infection Research, Hannover, Germany. (2016-05)
      Echinocandin resistance in Candida glabrata is emerging and is associated with the presence of FKS mutations. In this study, we analysed the antifungal susceptibility, presence of FKS mutations and clonality of C. glabrata blood culture isolates from two hospitals in Germany and Austria. Susceptibility testing of 64 C. glabrata bloodstream isolates from two university hospitals was performed with broth microdilution method according to EUCAST. In addition, all isolates were screened for FKS mutations. Molecular fingerprinting was performed by microsatellite PCR with three separate primer pairs and semiautomated repetitive sequenced-based PCR (rep-PCR). One C. glabrata isolate from Germany (1.5%) was echinocandin resistant, with a corresponding mutation in FKS2 gene hot spot 1. The discriminatory power of microsatellite PCR was higher than that of rep-PCR (Simpson Index of 0.94 vs. 0.88); microsatellite PCR created 31 separate genotypes, whereas rep-PCR created 17. Predominant genotypes or clusters of isolates from Germany and Austria were present, with no epidemiological evidence of nosocomial transmissions. Although we found a low incidence of echinocandin resistance in C. glabrata in our settings, further surveillance projects in central Europe are warranted for monitoring future epidemiological trends. The genetic population structure of C. glabrata demonstrates overrepresented geographical clusters.
    • Emergence of linezolid- and vancomycin-resistant Enterococcus faecium in a department for hematologic stem cell transplantation.

      Krull, M; Klare, I; Ross, B; Trenschel, R; Beelen, D W; Todt, D; Steinmann, E; Buer, J; Rath, P-M; Steinmann, J; Twincore Centre of Experimental and Clinical Infection Research; a joint venture between the Hannover Medical School and the Helmholtz Centre for Infection Research, Hannover 30625, Germany. (2016)
      Prevalence of vancomycin-resistant enterococci has increased in Germany. Here, we report the cluster of linezolid- and vancomycin-resistant Enterococcus faecium (LVRE) in a German department for hematologic stem cell transplantation (HSCT).
    • Environmental Stability and Infectivity of Hepatitis C Virus (HCV) in Different Human Body Fluids.

      Pfaender, Stephanie; Helfritz, Fabian A; Siddharta, Anindya; Todt, Daniel; Behrendt, Patrick; Heyden, Julia; Riebesehl, Nina; Willmann, Wiebke; Steinmann, Joerg; Münch, Jan; Ciesek, Sandra; Steinmann, Eike; TWINCORE, Zentrum für experimentelle und klinischeInfektionsforschung GmbH, Feodor-Lynen-Str. 7, 30625 Hannover, Germany. (2018-01-01)
      Hepatitis C virus (HCV) is a hepatotropic, blood-borne virus, but in up to one-third of infections of the transmission route remained unidentified. Viral genome copies of HCV have been identified in several body fluids, however, non-parental transmission upon exposure to contaminated body fluids seems to be rare. Several body fluids, e.g., tears and saliva, are renowned for their antimicrobial and antiviral properties, nevertheless, HCV stability has never been systematically analyzed in those fluids.
    • Exophiala dermatitidis isolates from various sources: using alternative invertebrate host organisms (Caenorhabditis elegans and Galleria mellonella) to determine virulence.

      Olsowski, Maike; Hoffmann, Frederike; Hain, Andrea; Kirchhoff, Lisa; Theegarten, Dirk; Todt, Daniel; Steinmann, Eike; Buer, Jan; Rath, Peter-Michael; Steinmann, Joerg; TWINCORE, Zentrum für experimentelle und klinische Infektionsforschung GmbH,Feodor-Lynen Str. 7, 30625 Hannover, Germany. (2018-08-24)
      Exophiala dermatitidis causes chromoblastomycosis, phaeohyphomycosis and fatal infections of the central nervous system of patients with Asian background. It is also found in respiratory secretions from cystic fibrosis (CF) patients. In this study a variety of E. dermatitidis strains (isolates from Asia, environmental and CF) were characterized in their pathogenicity by survival analyzes using two different invertebrate host organisms, Caenorhabditis elegans and Galleria mellonella. Furthermore, the morphological development of hyphal formation was analyzed. E. dermatitidis exhibited pathogenicity in C. elegans. The virulence varied in a strain-dependent manner, but the nematodes were a limited model to study hyphal formation. Analysis of a melanin-deficient mutant (Mel-3) indicates that melanin plays a role during virulence processes in C. elegans. The strains isolated from Asian patients exhibited significantly higher virulence in G. mellonella compared to strains from other sources. Histological analyzes also revealed a higher potential of invasive hyphal growth in strains isolated from Asian patients. Interestingly, no significant difference was found in virulence between the Mel-3 mutant and their wild type counterpart during infection in G. mellonella. In conclusion, invasive hyphal formation of E. dermatitidis was associated with increased virulence. This work is the basis for future studies concerning E. dermatitidis virulence.
    • Extra-hepatic replication and infection of hepatitis E virus in neuronal-derived cells.

      Drave, S A; Debing, Y; Walter, S; Todt, D; Engelmann, M; Friesland, M; Wedemeyer, H; Neyts, J; Behrendt, P; Steinmann, E; Twincore Centre of Experimental and Clinical Infection Research; a joint venture between the Hannover Medical School and the Helmholtz Centre for Infection Research, Hannover 30625, Germany. (2016-07)
      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.
    • Frequent presence of hepaci and pegiviruses in commercial equine serum pools.

      Postel, Alexander; Cavalleri, Jessika-M V; Pfaender, Stephanie; Walter, Stephanie; Steinmann, E; Fischer, Nicole; Feige, Karsten; Haas, Ludwig; Becher, Paul; Twincore Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hanover and the Helmholtz Centre for Infection Research, Hanover, Germany. (2016-01-15)
      Novel viruses belonging to the genera Hepacivirus and Pegivirus have recently been discovered in horses and other animal species. Viral genomes of non-primate hepaciviruses (NPHV), equine pegivirus 1 (EPgV 1) and Theiler's disease associated virus (TDAV) were detected in a horse serum routinely used for cell culture propagation in our laboratory. Therefore, a study was carried out to further investigate the presence of these human Hepatitis C virus (HCV) related viruses in equine serum based products used in veterinary medicine and for research and to characterize the viral genomes. Without exception all commercially available equine sera purchased for cell culture propagation (n=6) were tested positive for NPHV, EPgV 1 or TDAV genomes by qRT-PCR. Molecular analyses of one single commercial horse serum from Europe confirmed multiple viral genomes, including two TDAV genomes significantly different from the only published TDAV sequence. Furthermore, multiple batches of horse serum pools (n=35) collected for manufacturing of biological products turned out to be positive for NPHV and EPgV 1 genomes. Nevertheless, the final commercial products (n=9) were exclusively tested qRT-PCR negative. Field samples (n=119) obtained from two premises located in the same region as the donor horses were analyzed, demonstrating the frequent presence of NPHV and EPgV 1, but the absence of TDAV genomes. The presence of NPHV, EPgV 1 and TDAV in commercial equine sera and serum based products could have considerable consequences for biosecurity and may also bias the outcome of research studies conducted with related viruses.
    • Host cell mTORC1 is required for HCV RNA replication.

      Stöhr, Stefanie; Costa, Rui; Sandmann, Lisa; Westhaus, Sandra; Pfaender, Stephanie; Anggakusuma; Dazert, Eva; Meuleman, Philip; Vondran, Florian W R; Manns, Michael P; Steinmann, Eike; von Hahn, Thomas; Ciesek, Sandra; TWINCORE, Centre for Experimental and Clinical Infection Research; a joint venture between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), Hannover, Germany. (2015-08-14)
      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.
    • The impact of hepatitis E in the liver transplant setting.

      Behrendt, Patrick; Steinmann, Eike; Manns, Michael P; Wedemeyer, Heiner (2014-12)
      Hepatitis E virus (HEV) infection has been identified as a cause of graft hepatitis in liver transplant recipients. The true frequency and clinical importance of HEV infections after liver transplantations is a matter of debate. It is proposed that consumption of HEV-contaminated undercooked meat is a main source for HEV infections in developed countries--which might also account for some hepatitis E cases after organ transplantation. However, HEV is also transmitted by transfusion of blood products, likely representing a previously underestimated risk particularly for patients in the transplant setting. HEV infection can take chronic courses in immunocompromised individuals, associated in some cases with rapid progression to cirrhosis within 1-2 years of infection. Diagnosis in transplanted patients is based on HEV RNA testing as antibody assays are not sensitive enough. Selection of immunosuppressive drugs is important as different compounds may influence viral replication and the course of liver disease. Ribavirin has antiviral activity against HEV and should be administered for at least three months in chronically infected individuals; however, treatment failure may occur. HEV infections have also been linked to a variety of extrahepatic manifestations both during and after resolution of infection. In this review we summarize the emerging data on hepatitis E with a particular focus on the importance of HEV infections for liver transplant recipients.
    • In vivo evidence for ribavirin-induced mutagenesis of the hepatitis E virus genome.

      Todt, Daniel; Gisa, Anett; Radonic, Aleksandar; Nitsche, Andreas; Behrendt, Patrick; Suneetha, Pothakamuri Venkata; Pischke, Sven; Bremer, Birgit; Brown, Richard J P; Manns, Michael P; Cornberg, Markus; Bock, C Thomas; Steinmann, Eike; Wedemeyer, Heiner; Twincore Centre of Experimental and Clinical Infection Research; a joint venture between the Hannover Medical School and the Helmholtz Centre for Infection Research, Hannover 30625, Germany. (2016-10)
      Hepatitis E virus (HEV) infection can take chronic courses in immunocompromised patients potentially leading to liver cirrhosis and liver failure. Ribavirin (RBV) is currently the only treatment option for many patients, but treatment failure can occur which has been associated with the appearance of a distinct HEV polymerase mutant (G1634R). Here, we performed a detailed analysis of HEV viral intrahost evolution during chronic hepatitis E infections.
    • Inactivation of HCV and HIV by microwave: a novel approach for prevention of virus transmission among people who inject drugs.

      Siddharta, Anindya; Pfaender, Stephanie; Malassa, Angelina; Doerrbecker, Juliane; Anggakusuma; Engelmann, Michael; Nugraha, Boya; Steinmann, Joerg; Todt, Daniel; Vondran, Florian W R; Mateu-Gelabert, Pedro; Goffinet, Christine; Steinmann, Eike (2016-11-18)
      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.
    • Inactivation of Zika virus in human breast milk by prolonged storage or pasteurization.

      Pfaender, Stephanie; Vielle, Nathalie J; Ebert, Nadine; Steinmann, Eike; Alves, Marco P; Thiel, Volker; Twincore Centre of Experimental and Clinical Infection Research; a joint venture between the Hannover Medical School and the Helmholtz Centre for Infection Research, Hannover 30625, Germany. (2016-11-23)
      Zika virus infection during pregnancy poses a serious risk for pregnant women as it can cause severe birth defects. Even though the virus is mainly transmitted via mosquitos, human-to-human transmission has been described. Infectious viral particles have been detected in breast milk of infected women which raised concerns regarding the safety of breastfeeding in areas of Zika virus transmission or in case of a suspected or confirmed Zika virus infection. In this study, we show that Zika virus is effectively inactivated in human breast milk after prolonged storage or upon pasteurization of milk.
    • Mechanisms of methods for hepatitis C virus inactivation.

      Pfaender, Stephanie; Brinkmann, Janine; Todt, Daniel; Riebesehl, Nina; Steinmann, Joerg; Steinmann, Jochen; Pietschmann, Thomas; Steinmann, Eike; Institute for Experimental Virology, TWINCORE Centre for Experimental and Clinical Infection Research,Feodor-Lynen-Str. 7, 30625 Hannover, Germany. (2015-03-01)
      Virus inactivation by chemical disinfectants is an important instrument for infection control in medical settings, but the mechanisms involved are poorly understood. In this study, we systematically investigated the effects of several antiviral treatments on hepatitis C virus (HCV) particles as model for enveloped viruses. Studies were performed with authentic cell culture-derived viruses, and the influence of chemical disinfectants, heat, and UV treatment on HCV was analyzed by the determination of infectious particles in a limiting-dilution assay, by quantitative reverse transcription-PCR, by core enzyme-linked immunosorbent assay, and by proteolytic protection assay. All different inactivation methods resulted in a loss of HCV infectivity by targeting different parts of the virus particle. Alcohols such as ethanol and 2-propanol did not affect the viral RNA genome integrity but disrupted the viral envelope membrane in a capsid protection assay. Heat and UV treatment of HCV particles resulted in direct damage of the viral genome since transfection of viral particle-associated RNA into permissive cells did not initiate RNA replication. In addition, heat incubation at 80°C disrupted the HCV envelope, rendering the viral capsid susceptible to proteolytic digest. This study demonstrated the molecular processes of viral inactivation of an enveloped virus and should facilitate the development of effective disinfection strategies in infection control not only against HCV but also against other enveloped viruses.
    • Mutagenic Effects of Ribavirin on Hepatitis E Virus-Viral Extinction versus Selection of Fitness-Enhancing Mutations.

      Todt, Daniel; Walter, Stephanie; Brown, Richard J P; Steinmann, Eike; TWINCORE, Centre for experimental and clinical infection research GmbH, Feodor-Lynen Str. 7, 30625 Hannover, Germany. (2016-10-13)
      Hepatitis E virus (HEV), an important agent of viral hepatitis worldwide, can cause severe courses of infection in pregnant women and immunosuppressed patients. To date, HEV infections can only be treated with ribavirin (RBV). Major drawbacks of this therapy are that RBV is not approved for administration to pregnant women and that the virus can acquire mutations, which render the intra-host population less sensitive or even resistant to RBV. One of the proposed modes of action of RBV is a direct mutagenic effect on viral genomes, inducing mismatches and subsequent nucleotide substitutions. These transition events can drive the already error-prone viral replication beyond an error threshold, causing viral population extinction. In contrast, the expanded heterogeneous viral population can facilitate selection of mutant viruses with enhanced replication fitness. Emergence of these mutant viruses can lead to therapeutic failure. Consequently, the onset of RBV treatment in chronically HEV-infected individuals can result in two divergent outcomes: viral extinction versus selection of fitness-enhanced viruses. Following an overview of RNA viruses treated with RBV in clinics and a summary of the different antiviral modes of action of this drug, we focus on the mutagenic effect of RBV on HEV intrahost populations, and how HEV is able to overcome lethal mutagenesis.
    • 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; Meuleman, Philip; Steinmann, Eike; TWINCORE, Zentrum für experimentelle und klinischeInfektionsforschung GmbH, Feodor-Lynen-Str. 7, 30625 Hannover, Germany. (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.