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Pierce DM, Buchanan FJT, Macrae FL, Mills JT, Cox A, Abualsaoud KM, Ward JC, Ariëns RAS, Harris M, Stonehouse NJ, Herod MR. Thrombin cleavage of the hepatitis E virus polyprotein at multiple conserved locations is required for genome replication. PLoS Pathog 2023; 19:e1011529. [PMID: 37478143 PMCID: PMC10395923 DOI: 10.1371/journal.ppat.1011529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 07/03/2023] [Indexed: 07/23/2023] Open
Abstract
The genomes of positive-sense RNA viruses encode polyproteins that are essential for mediating viral replication. These viral polyproteins must undergo proteolysis (also termed polyprotein processing) to generate functional protein units. This proteolysis can be performed by virally-encoded proteases as well as host cellular proteases, and is generally believed to be a key step in regulating viral replication. Hepatitis E virus (HEV) is a leading cause of acute viral hepatitis. The positive-sense RNA genome is translated to generate a polyprotein, termed pORF1, which is necessary and sufficient for viral genome replication. However, the mechanism of polyprotein processing in HEV remains to be determined. In this study, we aimed to understand processing of this polyprotein and its role in viral replication using a combination of in vitro translation experiments and HEV sub-genomic replicons. Our data suggest no evidence for a virally-encoded protease or auto-proteolytic activity, as in vitro translation predominantly generates unprocessed viral polyprotein precursors. However, seven cleavage sites within the polyprotein (suggested by bioinformatic analysis) are susceptible to the host cellular protease, thrombin. Using two sub-genomic replicon systems, we demonstrate that mutagenesis of these sites prevents replication, as does pharmacological inhibition of serine proteases including thrombin. Overall, our data supports a model where HEV uses host proteases to support replication and could have evolved to be independent of a virally-encoded protease for polyprotein processing.
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Affiliation(s)
- Danielle M Pierce
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Frazer J T Buchanan
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Fraser L Macrae
- Discovery and Translational Science Department, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Jake T Mills
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Abigail Cox
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Khadijah M Abualsaoud
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
- Department of Laboratory and Blood Bank, Al Mikhwah General Hospital, Al Mikhwah, Saudi Arabia
| | - Joseph C Ward
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Robert A S Ariëns
- Discovery and Translational Science Department, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Mark Harris
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Nicola J Stonehouse
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Morgan R Herod
- School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
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2
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Bhise N, Agarwal M, Thakur N, Akshay PS, Cherian S, Lole K. Repurposing of artesunate, an antimalarial drug, as a potential inhibitor of hepatitis E virus. Arch Virol 2023; 168:147. [PMID: 37115342 PMCID: PMC10141844 DOI: 10.1007/s00705-023-05770-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 03/29/2023] [Indexed: 04/29/2023]
Abstract
Hepatitis E virus (HEV) is endemic in several developing countries of Africa and Asia. It mainly causes self-limiting waterborne infections, in either sporadic or outbreak form. Recently, HEV was shown to cause chronic infections in immunosuppressed individuals. Ribavirin and interferon, the current off-label treatment options for hepatitis E, have several side effects. Hence, there is a need for new drugs. We evaluated the antimalarial drug artesunate (ART) against genotype 1 HEV (HEV-1) and HEV-3 using a virus-replicon-based cell culture system. ART exhibited 59% and 43% inhibition of HEV-1 and HEV-3, respectively, at the highest nontoxic concentration. Computational molecular docking analysis showed that ART can bind to the helicase active site (affinity score, -7.4 kcal/mol), indicating its potential to affect ATP hydrolysis activity. An in vitro ATPase activity assay of the helicase indeed showed 24% and 55% inhibition at 19.5 µM (EC50) and 78 µM concentrations of ART, respectively. Since ATP is a substrate of RNA-dependent RNA polymerase (RdRp) as well, we evaluated the effect of ART on the enzymatic activity of the viral polymerase. Interestingly, ART showed 26% and 40% inhibition of the RdRp polymerase activity at 19.5 µM and 78 µM concentrations of ART, respectively. It could be concluded from these findings that ART inhibited replication of both HEV-1 and HEV-3 by directly targeting the activities of the viral enzymes helicase and RdRp. Considering that ART is known to be safe in pregnant women, we think this antimalarial drug deserves further evaluation in animal models.
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Affiliation(s)
- Neha Bhise
- Hepatitis Group, Indian Council of Medical Research-National Institute of Virology, Microbial Containment Complex, Pune, India
| | - Megha Agarwal
- Bioinformatics and Data Management Group, Indian Council of Medical Research-National Institute of Virology, Dr. Ambedkar Road, Pune, India
| | - Nidhi Thakur
- Hepatitis Group, Indian Council of Medical Research-National Institute of Virology, Microbial Containment Complex, Pune, India
| | - P S Akshay
- Hepatitis Group, Indian Council of Medical Research-National Institute of Virology, Microbial Containment Complex, Pune, India
| | - Sarah Cherian
- Bioinformatics and Data Management Group, ICMR-National Institute of Virology, 20-A, Dr. Ambedkar Road, Pune, 411001, India.
| | - Kavita Lole
- Hepatitis Group, ICMR-National Institute of Virology, Microbial Containment Complex, Sus Road, Pashan, Pune, 411021, India.
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3
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Ju X, Dong L, Ding Q. Hepatitis E Virus Life Cycle. Adv Exp Med Biol 2023; 1417:141-157. [PMID: 37223864 DOI: 10.1007/978-981-99-1304-6_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Hepatitis E virus (HEV) infects over 20 million people worldwide per year, leading to 30,000-40,000 deaths. In most cases HEV infection in a self-limited, acute illness. However, chronic infections could occur in immunocompromised individuals. Due to scarcity of robust cell culture models in vitro and genetic tractable animal models in vivo, the details of HEV life cycle, as well as its interaction with host cells still remain elusive, which dampens antivirals discovery. In this chapter, we present an update in the HEV infectious cycle steps: entry, genome replication/subgenomic RNA transcription, assembly, and release. Moreover, we discussed the future prospective on HEV research and illustrates important questions urgently to be addressed.
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Affiliation(s)
- Xiaohui Ju
- School of Medicine, Tsinghua University, Beijing, China
| | - Lin Dong
- School of Medicine, Tsinghua University, Beijing, China
| | - Qiang Ding
- School of Medicine, Tsinghua University, Beijing, China.
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Fieulaine S, Tubiana T, Bressanelli S. De novo modelling of HEV replication polyprotein: Five-domain breakdown and involvement of flexibility in functional regulation. Virology 2023; 578:128-140. [PMID: 36527931 DOI: 10.1016/j.virol.2022.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/01/2022] [Accepted: 12/02/2022] [Indexed: 12/14/2022]
Abstract
Hepatitis E virus (HEV), a major cause of acute viral hepatitis, is a single-stranded, positive-sense RNA virus. As such, it encodes a 1700-residue replication polyprotein pORF1 that directs synthesis of new viral RNA in infected cells. Here we report extensive modeling with AlphaFold2 of the full-length pORF1, and its production by in vitro translation. From this, we give a detailed update on the breakdown into domains of HEV pORF1. We also provide evidence that pORF1's N-terminal domain is likely to oligomerize to form a dodecameric pore, homologously to what has been described for Chikungunya virus. Beyond providing accurate folds for its five domains, our work highlights that there is no canonical protease encoded in pORF1 and that flexibility in several functionally important regions rather than proteolytic processing may serve to regulate HEV RNA synthesis.
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Affiliation(s)
- Sonia Fieulaine
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France.
| | - Thibault Tubiana
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France.
| | - Stéphane Bressanelli
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France.
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5
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He Q, Zhang Y, Gong W, Zeng H, Wang L. Genetic Evolution of Hepatitis E Virus. Adv Exp Med Biol 2023; 1417:59-72. [PMID: 37223859 DOI: 10.1007/978-981-99-1304-6_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Comparative analysis of the genomic sequences of multiple hepatitis E virus (HEV) isolates has revealed extensive genomic diversity among them. Recently, a variety of genetically distinct HEV variants have also been isolated and identified from large numbers of animal species, including birds, rabbits, rats, ferrets, bats, cutthroat trout, and camels, among others. Furthermore, it has been reported that recombination in HEV genomes takes place in animals and in human patients. Also, chronic HEV infection in immunocompromised individuals has revealed the presence of viral strains carrying insertions from human genes. This paper reviews current knowledge on the genomic variability and evolution of HEV.
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Affiliation(s)
- Qiyu He
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Yulin Zhang
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Wanyun Gong
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Hang Zeng
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Ling Wang
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China.
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6
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Abstract
Hepatitis E virus (HEV) is a leading cause of acute hepatitis worldwide. Hepatitis E is an enterically transmitted zoonotic disease that causes large waterborne epidemic outbreaks in developing countries and has become an increasing public-health concern in industrialized countries. In this setting, the infection is usually acute and self-limiting in immunocompetent individuals, although chronic cases in immunocompromised patients have been reported, frequently associated with several extrahepatic manifestations. Moreover, extrahepatic manifestations have also been reported in immunocompetent individuals with acute HEV infection. HEV belongs to the alphavirus-like supergroup III of single-stranded positive-sense RNA viruses, and its genome contains three partially overlapping open reading frames (ORFs). ORF1 encodes a nonstructural protein with eight domains, most of which have not been extensively characterized: methyltransferase, Y domain, papain-like cysteine protease, hypervariable region, proline-rich region, X domain, Hel domain, and RNA-dependent RNA polymerase. ORF2 and ORF3 encode the capsid protein and a multifunctional protein believed to be involved in virion release, respectively. The novel ORF4 is only expressed in HEV genotype 1 under endoplasmic reticulum stress conditions, and its exact function has not yet been elucidated. Despite important advances in recent years, the biological and molecular processes underlying HEV replication remain poorly understood, primarily due to a lack of detailed information about the functions of the viral proteins and the mechanisms involved in host-pathogen interactions. This review summarizes the current knowledge concerning HEV proteins and their biological properties, providing updated detailed data describing their function and focusing in detail on their structural characteristics. Furthermore, we review some unclear aspects of the four proteins encoded by the ORFs, highlighting the current key information gaps and discussing potential novel experimental strategies for shedding light on those issues.
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Affiliation(s)
- Florencia Cancela
- grid.11630.350000000121657640Sección Virología, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Ofelia Noceti
- grid.414402.70000 0004 0469 0889Programa Nacional de Trasplante Hepático y Unidad Docente Asistencial Centro Nacional de Tratamiento Hepatobiliopancreatico. Hospital Central de las Fuerzas Armadas, Montevideo, Uruguay
| | - Juan Arbiza
- grid.11630.350000000121657640Sección Virología, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Santiago Mirazo
- grid.11630.350000000121657640Sección Virología, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay ,grid.11630.350000000121657640Departamento de Bacteriología y Virología, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay ,Av. Alfredo Navarro 3051, PC 11600 Montevideo, Uruguay
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7
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Ju X, Xiang G, Gong M, Yang R, Qin J, Li Y, Nan Y, Yang Y, Zhang QC, Ding Q. Identification of functional cis-acting RNA elements in the hepatitis E virus genome required for viral replication. PLoS Pathog 2020; 16:e1008488. [PMID: 32433693 PMCID: PMC7239442 DOI: 10.1371/journal.ppat.1008488] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/22/2020] [Indexed: 12/29/2022] Open
Abstract
There are approximately 20 million events of hepatitis E virus (HEV) infection worldwide annually. The genome of HEV is a single-strand, positive-sense RNA containing 5’ and 3’ untranslated regions and three open reading frames (ORF). HEV genome has 5’ cap and 3’ poly(A) tail to mimic host mRNA to escape the host innate immune surveillance and utilize host translational machineries for viral protein translation. The replication mechanism of HEV is poorly understood, especially how the viral polymerase distinguishes viral RNA from host mRNA to synthesize new viral genomes. We hypothesize that the HEV genome contains cis-acting elements that can be recognized by the virally encoded polymerase as “self” for replication. To identify functional cis-acting elements systematically across the HEV genome, we utilized an ORF1 transcomplementation system. Ultimately, we found two highly conserved cis-acting RNA elements within the ORF1 and ORF2 coding regions that are required for viral genome replication in a diverse panel of HEV genotypes. Synonymous mutations in the cis-acting RNA elements, not altering the ORF1 and ORF2 protein sequences, significantly impaired production of infectious viral particles. Mechanistic studies revealed that the cis-acting elements form secondary structures needed to interact with the HEV ORF1 protein to promote HEV replication. Thus, these cis-acting elements function as a scaffold, providing a specific “signal” that recruits viral and host factors to assemble the viral replication complex. Altogether, this work not only facilitates our understanding of the HEV life cycle and provides novel, RNA-directed targets for potential HEV treatments, but also sheds light on the development of HEV as a therapeutic delivery vector. Hepatitis E virus (HEV) is an underestimated pathogen, causing approximately 20 million infections worldwide annually and leading to about 60,000 deaths. There are no direct-acting antivirals for treating HEV, and although significant progress has been made to establish robust HEV cell culture models, the life cycle remains poorly characterized. A better understanding of HEV replication could facilitate the development of new drugs targeting this critical process. Our study found that RNA elements in the HEV genome interact with the HEV replicases to promote viral replication, suggesting that these RNA elements function as a scaffold for recruitment and assembly of the viral replication complex. This work furthers our understanding of HEV replication and could inform the generation of RNA-based therapeutics for treating HEV infection.
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Affiliation(s)
- Xiaohui Ju
- Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
| | - Guangtao Xiang
- Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
| | - Mingli Gong
- Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
| | - Rui Yang
- School of Life Sciences, Tsinghua University, Beijing, China
| | - Jierui Qin
- Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
| | - Yafei Li
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
| | - Yuchen Nan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
| | - Yonglin Yang
- Department of General Practice, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Qiangfeng Cliff Zhang
- School of Life Sciences, Tsinghua University, Beijing, China
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, China
| | - Qiang Ding
- Center for Infectious Disease Research, School of Medicine, Tsinghua University, Beijing, China
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, China
- * E-mail:
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8
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Abstract
Hepatitis E virus (HEV) is a small quasi-enveloped, (+)-sense, single-stranded RNA virus belonging to the Hepeviridae family. There are at least 20 million HEV infections annually and 60,000 HEV-related deaths worldwide. HEV can cause up to 30% mortality in pregnant women and progress to liver cirrhosis in immunocompromised individuals and is, therefore, a greatly underestimated public health concern. Although a prophylactic vaccine for HEV has been developed, it is only licensed in China, and there is currently no effective, non-teratogenic treatment. HEV encodes three open reading frames (ORFs). ORF1 is the largest viral gene product, encoding the replicative machinery of the virus including a methyltransferase, RNA helicase, and an RNA-dependent RNA polymerase. ORF1 additionally contains a number of poorly understood domains including a hypervariable region, a putative protease, and the so-called ‘X’ and ‘Y’ domains. ORF2 is the viral capsid essential for formation of infectious particles and ORF3 is a small protein essential for viral release. In this review, we focus on the domains encoded by ORF1, which collectively mediate the virus’ asymmetric genome replication strategy. We summarize what is known, unknown, and hotly debated regarding the coding and non-coding regions of HEV ORF1, and present a model of how HEV replicates its genome.
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Affiliation(s)
- Robert LeDesma
- Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, NJ 08544, USA
| | - Ila Nimgaonkar
- Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, NJ 08544, USA
| | - Alexander Ploss
- Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, NJ 08544, USA.
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9
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Abstract
Hepatitis E virus (HEV) possesses many of the features of other positive-stranded RNA viruses but also adds HEV-specific nuances, making its virus-host interactions unique. Slow virus replication kinetics and fastidious growth conditions, coupled with the historical lack of an efficient cell culture system to propagate the virus, have left many gaps in our understanding of its structure and replication cycle. Recent advances in culturing selected strains of HEV and resolving the 3D structure of the viral capsid are filling in knowledge gaps, but HEV remains an extremely understudied pathogen. Many steps in the HEV life cycle and many aspects of HEV pathogenesis remain unknown, such as the host and viral factors that determine cross-species infection, the HEV-specific receptor(s) on host cells, what determines HEV chronicity and the ability to replicate in extrahepatic sites, and what regulates processing of the open reading frame 1 (ORF1) nonstructural polyprotein.
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Affiliation(s)
- Scott P Kenney
- Food Animal Health Research Program, The Ohio State University, Wooster, Ohio 44691
| | - Xiang-Jin Meng
- Department of Biomedical Sciences and Pathobiology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
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Parvez MK, Subbarao N. Molecular Analysis and Modeling of Hepatitis E Virus Helicase and Identification of Novel Inhibitors by Virtual Screening. Biomed Res Int 2018; 2018:5753804. [PMID: 30246023 DOI: 10.1155/2018/5753804] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 08/07/2018] [Indexed: 12/20/2022]
Abstract
The hepatitis E virus- (HEV-) helicase as a novel drug-target was evaluated. While cell culture model was used for mutational characterization of helicase, in silico protein modeling and virtual screening were employed to identify helicase inhibitors. None of the saturation mutant replicons significantly affected RNA replication. Notably, mutants encompassing the Walker motifs replicated as wild-type, showing indispensability of nucleotides conservation in viability compared to known criticality of amino acids. A 3D modeling of HEV-helicase and screening of a compound dataset identified ten most promising inhibitors with drug likeness, notably, JFD02650, RDR03130, and HTS11136 that interacted with Walker A residues Gly975, Gly978, Ser979, and Gly980. Our model building and virtual identification of novel helicase inhibitors warrant further studies towards developing anti-HEV drugs.
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11
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Abstract
Hepatitis E virus (HEV) is a globally important pathogen of acute and chronic hepatitis in humans. The HEV ORF1 gene encodes a nonstructural polyprotein, essential for RNA replication and virus infectivity. Expression and processing of ORF1 polyprotein are shown in prokaryotic and eukaryotic systems, however, its proteolysis into individual proteins is still debated. While molecular or biochemical characterization of methyltransferase, protease, hypervariable region, helicase and RNA polymerase domains in ORF1 has been achieved, the role of the X and Y domains in the HEV life cycle has only been demonstrated very recently. Clinically, detection of a number of ORF1 mutants in infected patients is implicated in disease severity, mortality and drug nonresponse. Moreover, several artificial lethal mutations in ORF1 offer a potential basis for developing live-attenuated vaccines for HEV. This article intends to present the molecular and clinical updates on the HEV ORF1 polyprotein.
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Affiliation(s)
- Mohammad Khalid Parvez
- Department of Pharmacognosy, King Saud University College of Pharmacy, Riyadh 11451, Saudi Arabia
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12
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Li C, Debing Y, Jankevicius G, Neyts J, Ahel I, Coutard B, Canard B. Viral Macro Domains Reverse Protein ADP-Ribosylation. J Virol 2016; 90:8478-86. [PMID: 27440879 DOI: 10.1128/JVI.00705-16] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 07/05/2016] [Indexed: 12/27/2022] Open
Abstract
UNLABELLED ADP-ribosylation is a posttranslational protein modification in which ADP-ribose is transferred from NAD(+) to specific acceptors to regulate a wide variety of cellular processes. The macro domain is an ancient and highly evolutionarily conserved protein domain widely distributed throughout all kingdoms of life, including viruses. The human TARG1/C6orf130, MacroD1, and MacroD2 proteins can reverse ADP-ribosylation by acting on ADP-ribosylated substrates through the hydrolytic activity of their macro domains. Here, we report that the macro domain from hepatitis E virus (HEV) serves as an ADP-ribose-protein hydrolase for mono-ADP-ribose (MAR) and poly(ADP-ribose) (PAR) chain removal (de-MARylation and de-PARylation, respectively) from mono- and poly(ADP)-ribosylated proteins, respectively. The presence of the HEV helicase in cis dramatically increases the binding of the macro domain to poly(ADP-ribose) and stimulates the de-PARylation activity. Abrogation of the latter dramatically decreases replication of an HEV subgenomic replicon. The de-MARylation activity is present in all three pathogenic positive-sense, single-stranded RNA [(+)ssRNA] virus families which carry a macro domain: Coronaviridae (severe acute respiratory syndrome coronavirus and human coronavirus 229E), Togaviridae (Venezuelan equine encephalitis virus), and Hepeviridae (HEV), indicating that it might be a significant tropism and/or pathogenic determinant. IMPORTANCE Protein ADP-ribosylation is a covalent posttranslational modification regulating cellular protein activities in a dynamic fashion to modulate and coordinate a variety of cellular processes. Three viral families, Coronaviridae, Togaviridae, and Hepeviridae, possess macro domains embedded in their polyproteins. Here, we show that viral macro domains reverse cellular ADP-ribosylation, potentially cutting the signal of a viral infection in the cell. Various poly(ADP-ribose) polymerases which are notorious guardians of cellular integrity are demodified by macro domains from members of these virus families. In the case of hepatitis E virus, the adjacent viral helicase domain dramatically increases the binding of the macro domain to PAR and simulates the demodification activity.
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13
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Abstract
Hepatitis E virus (HEV) is a viral pathogen transmitted primarily via fecal-oral route. In humans, HEV mainly causes acute hepatitis and is responsible for large outbreaks of hepatitis across the world. The case fatality rate of HEV-induced hepatitis ranges from 0.5 to 3% in young adults and up to 30% in infected pregnant women. HEV strains infecting humans are classified into four genotypes. HEV strains from genotypes 3 and 4 are zoonotic, whereas those from genotypes 1 and 2 have no known animal reservoirs. Recently, notable progress has been accomplished for better understanding of HEV biology and infection, such as chronic HEV infection, in vitro cell culture system, quasi-enveloped HEV virions, functions of the HEV proteins, mechanism of HEV antagonizing host innate immunity, HEV pathogenesis and vaccine development. However, further investigation on the cross-species HEV infection, host tropism, vaccine efficacy, and HEV-specific antiviral strategy is still needed. This review mainly focuses on molecular biology and infection of HEV and offers perspective new insight of this enigmatic virus.
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Affiliation(s)
- Yuchen Nan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F UniversityYangling, China; Molecular Virology Laboratory, VA-MD College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, College ParkMD, USA
| | - Yan-Jin Zhang
- Molecular Virology Laboratory, VA-MD College of Veterinary Medicine and Maryland Pathogen Research Institute, University of Maryland, College Park, College Park MD, USA
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van Tong H, Hoan NX, Wang B, Wedemeyer H, Bock CT, Velavan TP. Hepatitis E Virus Mutations: Functional and Clinical Relevance. EBioMedicine 2016; 11:31-42. [PMID: 27528267 PMCID: PMC5049923 DOI: 10.1016/j.ebiom.2016.07.039] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 07/29/2016] [Indexed: 02/07/2023] Open
Abstract
Hepatitis E virus (HEV) infection is a major cause of acute hepatitis and affects more than 20 million individuals, with three million symptomatic cases and 56,000 recognized HEV-related deaths worldwide. HEV is endemic in developing countries and is gaining importance in developed countries, due to increased number of autochthone cases. Although HEV replication is controlled by the host immune system, viral factors (especially specific viral genotypes and mutants) can modulate HEV replication, infection and pathogenesis. Limited knowledge exists on the contribution of HEV genome variants towards pathogenesis, susceptibility and to therapeutic response. Nonsynonymous substitutions can modulate viral proteins structurally and thus dysregulate virus-host interactions. This review aims to compile knowledge and discuss recent advances on the casual role of HEV heterogeneity and its variants on viral morphogenesis, pathogenesis, clinical outcome and antiviral resistance. HEV causes acute hepatitis and recently comes into focus because of persistent infection in immunocompromised patients. HEV variability can be associated with clinical pathogenesis and transmission dynamics. Mutations in the HEV genome can influence HEV physiology and virus-host interaction. HEV mutations and variability are likely associated with fulminant hepatic failure and chronic hepatitis E. The Y1320H and G1634R/K mutations in the RdRp domain contribute to antiviral resistance through enhancing HEV replication.
We searched MEDLINE database and PubMed for articles from 1980 through June 30, 2016. Search terms used in various combinations were “hepatitis E”, “hepatitis E virus”, “hepatitis E virus infection”, “hepatitis E virus mutation”, “HEV variability”, “HEV genotype”, “HEV drug resistance”, “HEV replication” and “ribavirin”. Articles resulting from these searches and relevant references cited in those articles were selected based on their related topics and were reviewed. Abstracts and reports from meetings were also included. Articles published in English were included.
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Affiliation(s)
- Hoang van Tong
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.
| | - Nghiem Xuan Hoan
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Bo Wang
- Department of Infectious Diseases, Robert Koch Institute, Berlin, Germany
| | - Heiner Wedemeyer
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - C-Thomas Bock
- Department of Infectious Diseases, Robert Koch Institute, Berlin, Germany.
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Devhare P, Sharma K, Mhaindarkar V, Arankalle V, Lole K. Analysis of helicase domain mutations in the hepatitis E virus derived from patients with fulminant hepatic failure: effects on enzymatic activities and virus replication. Virus Res 2014; 184:103-10. [PMID: 24630891 DOI: 10.1016/j.virusres.2014.02.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 02/19/2014] [Accepted: 02/19/2014] [Indexed: 12/30/2022]
Abstract
Effect of fulminant hepatic failure (FHF) associated mutations on helicase activities and virus replication were checked. All the FHF mutants showed comparable unwinding activities with the wild type protein despite the differences in ATPase activities. All the FHF mutant replicons showed marginal decrease in virus replication compared to the wild type replicon suggesting alternate function/s of the helicase protein. Walker A motif and Walker B motif in the helicase domain are indispensable for HEV replication.
Fulminant hepatic failure (FHF) is the severe form of hepatitis E virus infection. Virus sequence analyses from severe cases have shown presence of unique and highly conserved mutations in the helicase domain of genotype 1, 3 and 4 viruses. We evaluated role of two amino acid replacements (L1110F) and (V1120I); found to be frequent in genotype 1 FHF-E viruses from India. Three mutant helicase proteins (two with single point mutations and one with dual mutations) were expressed in Escherichia coli and evaluated for their ATPase and RNA unwinding activities. Both L1110F and V1120I helicase mutants showed marginal decrease in ATPase activity, while L1110F/V1120I dual mutant showed normal ATPase activity. All three mutants proteins showed RNA unwinding activities comparable to wild type protein. Corresponding mutations were made in the helicase domain of HEV RLuc replicon and replication efficiencies were tested in the S10-3 (Huh 7) cells. The mutant replicon V1120I showed lower replication as compared to L1110F and L1110F/V1120I mutants. However, all three replicon mutants showed lower replication efficiencies as compared to the wild type replicon. Walker A and Walker B motif mutant HEV replicons were unable to replicate indicating essential role of the virus encoded helicase domain during HEV replication. FHF-E associated helicase mutations resulted in only marginal decrease in the virus replication suggesting alternate function/s of the helicase protein. Mutations in the helicase domain of FHF-E viruses may be responsible for changing virus or host-virus protein–protein interactions, causing alterations in the host responses, eventually leading to more severe disease manifestations.
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