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Taherkhani R, Farshadpour F, Makvandi M. Design and production of a multiepitope construct derived from hepatitis E virus capsid protein. J Med Virol 2015; 87:1225-34. [PMID: 25784455 PMCID: PMC7159329 DOI: 10.1002/jmv.24171] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/26/2015] [Indexed: 11/15/2022]
Abstract
The aim of this study was to design a high density multiepitope protein, which can be a promising multiepitope vaccine candidate against Hepatitis E virus (HEV). Initially, conserved and antigenic helper T‐lymphocyte (HTL) epitopes in the HEV capsid protein were predicted by in silico analysis. Subsequently, a multiepitope comprising four HTL epitopes with high‐affinity binding to the HLA molecules was designed, and repeated four times as high density multiepitope construct. This construct was synthesized and cloned into pET‐30a (+) vector. Then, it was transformed and expressed in Escherichia coli BL21 cells. The high density multiepitope protein was purified by Ni‐NTA agarose and concentrated using Amicon filters. Finally, the immunological properties of this high density multiepitope protein were evaluated in vitro. The results showed that the high density multiepitope construct was successfully expressed and purified. SDS‐PAGE and Western blot analyses showed the presence of a high density multiepitope protein band of approximately 33 kDa. Approximately 1 mg of the purified protein was obtained from each liter of the culture media. Moreover, the purified multiepitope protein was capable of induction of proliferation responses, IFN‐γ ELISPOT responses and IFN‐γ and IL‐12 cytokines production in a significant level in peripheral blood mononuclear cells (PBMCs) isolated from HEV‐recovered individuals compared to the control group. In conclusion, the newly produced multiepitope protein can induce significant T helper type 1 responses in vitro, and can be considered as a novel strategy for the development of HEV vaccines in the future. J. Med. Virol. 87:1225–1234, 2015. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Reza Taherkhani
- Department of Microbiology and Parasitology, School of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran; Persian Gulf Biomedical Research Center, Bushehr University of Medical Sciences, Bushehr, Iran
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Farshadpour F, Taherkhani R, Makvandi M, Rajabi Memari H, Samarbafzadeh AR. Codon-Optimized Expression and Purification of Truncated ORF2 Protein of Hepatitis E Virus in Escherichia coli. Jundishapur J Microbiol 2014; 7:e11261. [PMID: 25368796 PMCID: PMC4216576 DOI: 10.5812/jjm.11261] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 06/01/2013] [Accepted: 06/25/2013] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Hepatitis E virus (HEV) is a causative agent of acute hepatitis among people of different age groups and has high mortality rate of up to 30% among pregnant women. Therefore, primary prevention of HEV infection is essential. OBJECTIVES The aim of this study was to obtain the highly purified truncated open reading frames 2 (ORF2) protein, which might be a future HEV vaccine candidate. MATERIALS AND METHODS The truncated orf2 gene (orf2.1), encoding the 112-660 amino acid of HEV capsid protein sequence, was optimized, synthesized, and cloned into pBluescript II SK(+) vector. After subcloning into expression vector pET-30a (+), a 193-nucleotide fragment was deleted from the construct and the recombinant plasmid pET-30a-ORF2.2 (orf2.2 encodes 112-608 amino acid sequence of HEV capsid protein) was constructed and used for transformation of Escherichia coli BL21 cells. After induction with isopropyl-β-D-thiogalactopyranoside (IPTG) and optimizing the conditions of expression, the target protein was highly expressed and purified by Ni(2+)-chelate affinity chromatography. The expressed and purified protein was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. RESULTS The subcloning was confirmed by PCR, restriction enzyme digestion, and DNA sequencing of recombinant plasmid pET30a-ORF2.2. The results obtained from optimizing the expression conditions showed that the highest expression of the protein was obtained by adding IPTG at a final concentration of 1 mM at 37℃ for four hours. The expression and purification of truncated ORF2 protein was confirmed by SDS-PAGE and western blotting. SDS-PAGE analysis showed a protein band of about 55 kDa. SDS-PAGE of the purified protein revealed that the highest amount of target protein in elution buffer at the pH of 4.5 was obtained. The yield of the purified protein was about 1 mg/L of culture media. CONCLUSIONS In this study, the optimized truncated ORF2 protein was expressed in E. coli successfully and the highly purified protein was obtained, which can be a potential vaccine candidate and as an antigen in ELISA to diagnose HEV infections.
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Affiliation(s)
- Fatemeh Farshadpour
- Health Research Institute, Infectious and Tropical Disease Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran
- Department of Medical Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran
| | - Reza Taherkhani
- Health Research Institute, Infectious and Tropical Disease Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran
- Department of Medical Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran
| | - Manoochehr Makvandi
- Health Research Institute, Infectious and Tropical Disease Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran
- Department of Medical Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran
- Corresponding author: Manoochehr Makvandi, Health Research Institute, Infectious and Tropical Disease Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran; Department of Medical Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran. Tel: +98-9166181683, Fax: +98-6113738313, E-mail:
| | - Hamid Rajabi Memari
- Department of Agronomy and Plant Breeding, Faculty of Agriculture, Ahvaz Shahid Chamran University, Ahvaz, IR Iran
| | - Ali Reza Samarbafzadeh
- Health Research Institute, Infectious and Tropical Disease Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran
- Department of Medical Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran
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Abstract
Hepatitis E virus (HEV) infection is a worldwide disease. An improved understanding of the natural history of HEV infection has been achieved within the last decade. Several reservoirs and transmission modes have been identified. Hepatitis E is an underdiagnosed disease, in part due to the use of serological assays with low sensitivity. However, diagnostic tools, including nucleic acid-based tests, have been improved. The epidemiology and clinical features of hepatitis E differ between developing and developed countries. HEV infection is usually an acute self-limiting disease, but in developed countries it causes chronic infection with rapidly progressive cirrhosis in organ transplant recipients, patients with hematological malignancy requiring chemotherapy, and individuals with HIV. HEV also causes extrahepatic manifestations, including a number of neurological syndromes and renal injury. Acute infection usually requires no treatment, but chronic infection should be treated by reducing immunosuppression in transplant patients and/or the use of antiviral therapy. In this comprehensive review, we summarize the current knowledge about the virus itself, as well as the epidemiology, diagnostics, natural history, and management of HEV infection in developing and developed countries.
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Taherkhani R, Makvandi M, Farshadpour F. Development of enzyme-linked immunosorbent assays using 2 truncated ORF2 proteins for detection of IgG antibodies against hepatitis E virus. Ann Lab Med 2014; 34:118-26. [PMID: 24624347 PMCID: PMC3948824 DOI: 10.3343/alm.2014.34.2.118] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 09/12/2013] [Accepted: 10/02/2013] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Without appropriate culture systems for hepatitis E virus (HEV), sufficient natural viral proteins are difficult to generate for use in serological tests. Therefore, it is important to produce large amounts of HEV recombinant proteins in an economical way. The present study developed ELISAs using 2 truncated forms of the HEV open reading frame (ORF) 2 protein in order to detect anti-HEV IgG in serum samples. METHODS Two truncated forms of the ORF2 protein were expressed in Escherichia coli and were purified by Ni(2+)-chelate-affinity chromatography (Qiagen, Germany). Two ELISAs were developed using these proteins and were compared with DIA.PRO HEV IgG ELISA kit (DIA.PRO. Italy) in 220 serum samples. RESULTS High yields of the target proteins were obtained through codon optimization. The concentration and purity of the proteins were improved with Amicon filters (EMD Millipore, USA). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting analysis of the resultant proteins showed a protein band of approximately 60 kDa corresponding to ORF2.1 (amino acids 112-660) and a protein band of approximately 55 kDa corresponding to ORF2.2 (amino acids 112-607). Positive agreement, negative agreement, and concordance of the 2 in-house ELISAs compared with DIA.PRO HEV IgG ELISA kit were 87%, 99.5%, and 98.1%, respectively (kappa=0.899, P=0.625). CONCLUSIONS The newly developed ELISAs are useful for detecting anti-HEV IgG in serum samples and are highly concordant with DIA.PRO HEV IgG ELISA kit.
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Affiliation(s)
- Reza Taherkhani
- Health Research Institute, Infectious and Tropical Disease Research Center, Ahvaz Jundishapur University of Medical Scien, Ahvaz, Iran. ; Department of Medical Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Manoochehr Makvandi
- Health Research Institute, Infectious and Tropical Disease Research Center, Ahvaz Jundishapur University of Medical Scien, Ahvaz, Iran. ; Department of Medical Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Fatemeh Farshadpour
- Health Research Institute, Infectious and Tropical Disease Research Center, Ahvaz Jundishapur University of Medical Scien, Ahvaz, Iran. ; Department of Medical Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
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Taherkhani R, Makvandi M, Farshadpour F. Development of Enzyme-Linked Immunosorbent Assays Using 2 Truncated ORF2 Proteins for Detection of IgG Antibodies Against Hepatitis E Virus. Ann Lab Med 2014. [DOI: 10.3343/alm.2014.34.2.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Reza Taherkhani
- Health Research Institute, Infectious and Tropical Disease Research Center, Ahvaz Jundishapur University of Medical Scien, Ahvaz, Iran
- Department of Medical Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Manoochehr Makvandi
- Health Research Institute, Infectious and Tropical Disease Research Center, Ahvaz Jundishapur University of Medical Scien, Ahvaz, Iran
- Department of Medical Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Fatemeh Farshadpour
- Health Research Institute, Infectious and Tropical Disease Research Center, Ahvaz Jundishapur University of Medical Scien, Ahvaz, Iran
- Department of Medical Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
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Baechlein C, Meemken D, Pezzoni G, Engemann C, Grummer B. Expression of a truncated hepatitis E virus capsid protein in the protozoan organism Leishmania tarentolae and its application in a serological assay. J Virol Methods 2013; 193:238-43. [DOI: 10.1016/j.jviromet.2013.05.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 05/14/2013] [Accepted: 05/28/2013] [Indexed: 01/05/2023]
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Abstract
OBJECTIVE To study the complex formed between Tat protein and Env soluble trimeric immunogen, and compare with previously determined structures of Env native trimers and Env-CD4m complexes. DESIGN The soluble Env trimer was used to mimic the spike glycoprotein on the virus surface for the study. To overcome limitations of other structural determination methods, cryoelectron microscopy was employed to image the complex, and single particle reconstruction was utilized to reconstruct the structure of the complex from collected micrographs. Molecular modeling of gp120-Tat was performed to provide atomic coordinates for docking. METHODS Images were preprocessed by multivariate statistical analysis to identify principal components of variation then submitted for reconstruction. Reconstructed structures were docked with modeled gp120-Tat atomic coordinates to study the positions of crucial epitopes. RESULTS Analysis of the Env-Tat complex demonstrated an intermediate structure between Env native trimers and Env-CD4m structures. Docking results indicate that the CD4-binding site and the V3 loop are exposed in the Env-Tat complex. The integrin-binding sequence in Tat was also exposed in Env-Tat docking. CONCLUSION The intermediate structure induced by Tat-interaction with Env could potentially provide an explanation for increased virus infection in the presence of Tat protein. Consequently, exposure of CD4-binding sites and a putative integrin-binding sequence on Tat in the complex may provide a new avenue for rational design of an effective HIV vaccine.
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The hepatitis E virus capsid C-terminal region is essential for the viral life cycle: implication for viral genome encapsidation and particle stabilization. J Virol 2013; 87:6031-6. [PMID: 23468481 DOI: 10.1128/jvi.00444-13] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Although the C-terminal 52 amino acids (C52aa) of hepatitis E virus (HEV) capsid are not essential for morphology, the C52aa-encoding region is required for replication. Transfection of a C52aa knockdown mutant showed transient growth, and the earliest population included a majority of noninfectious (possibly empty) particles and a minority of infectious particles with C-terminal capsid degradation. Finally, the complete revertant was generated reproducibly. C52aa is essential for the viral life cycle, promoting accurate encapsidation and stabilizing encapsidated particles.
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Zhao Q, Zhang J, Wu T, Li SW, Ng MH, Xia NS, Shih JWK. Antigenic determinants of hepatitis E virus and vaccine-induced immunogenicity and efficacy. J Gastroenterol 2013; 48:159-68. [PMID: 23149436 PMCID: PMC3698418 DOI: 10.1007/s00535-012-0701-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 10/08/2012] [Indexed: 02/07/2023]
Abstract
There is emerging evidence for an under-recognized hepatitis E virus (HEV) as a human pathogen. Among different reasons for this neglect are the unsatisfactory performance and under-utilization of commercial HEV diagnostic kits; for instance, the number of anti-HEV IgM kits marketed in China is about one-fifth of that of hepatitis A kits. Over the last two decades, substantial progress has been achieved in furthering our knowledge on the HEV-specific immune responses, antigenic features of HEV virions, and development of serological assays and more recently prophylactic vaccines. This review will focus on presenting the evidence of the importance of HEV infection for certain cohorts such as pregnant women, the key antigenic determinants of the virus, and immunogenicity and clinical efficacy conferred by a newly developed prophylactic vaccine. Robust immunogenicity, greater than 195-fold and approximately 50-fold increase of anti-HEV IgG level in seronegative and seropositive vaccinees, respectively, as well as impressive clinical efficacy of this vaccine was demonstrated. The protection rate against the hepatitis E disease and the virus infection was shown to be 100% (95% CI 75-100) and 78% (95% CI 66-86), respectively.
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Affiliation(s)
- Qinjian Zhao
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, 422 Siming South Road, Xiamen, 361005 People’s Republic of China
| | - Jun Zhang
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, 422 Siming South Road, Xiamen, 361005 People’s Republic of China
| | - Ting Wu
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, 422 Siming South Road, Xiamen, 361005 People’s Republic of China
| | - Shao-Wei Li
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, 422 Siming South Road, Xiamen, 361005 People’s Republic of China
| | - Mun-Hon Ng
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, 422 Siming South Road, Xiamen, 361005 People’s Republic of China
| | - Ning-Shao Xia
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, 422 Siming South Road, Xiamen, 361005 People’s Republic of China
| | - James Wai-Kuo Shih
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, 422 Siming South Road, Xiamen, 361005 People’s Republic of China
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Jariyapong P, Xing L, van Houten NE, Li TC, Weerachatyanukul W, Hsieh B, Moscoso CG, Chen CC, Niikura M, Cheng RH. Chimeric hepatitis E virus-like particle as a carrier for oral-delivery. Vaccine 2012; 31:417-24. [PMID: 23107594 DOI: 10.1016/j.vaccine.2012.10.073] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Revised: 10/12/2012] [Accepted: 10/19/2012] [Indexed: 12/22/2022]
Abstract
Oral delivery with virus-like particles (VLPs) is advantageous because of the inherited entry pathway from their parental viral capsids, which enables VLP to withstand the harsh and enzymatic environment associated with human digestive tract. However, the repeat use of this system is challenged by the self-immunity. In order to overcome this problem, we engineered the recombinant capsid protein of hepatitis E virus by inserting p18 peptide, derived from the V3 loop of HIV-1 gp120, into the antibody-binding site. The chimeric VLP resembled the tertiary and quaternary structures of the wild type VLP and specifically reacted with an HIV-1 antibody against V3 loop. Different from the wild type VLP, the chimeric VLP was vulnerable to trypsin cleavage although it appeared as intact particle, suggesting that the intermolecular forces of attraction between the recombinant capsid proteins are strong enough to maintain the VLP icosahedral arrangement. Importantly, this VLP containing the V3 loop did not react with anti-HEV antibodies, in correspondence to the mutation at its antibody-binding site. Therefore, the insertion of peptides at the surface antigenic site could allow VLPs to escape pre-existing anti-HEV humoral immunity.
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Affiliation(s)
- Pitchanee Jariyapong
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, United States
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Cao D, Meng XJ. Molecular biology and replication of hepatitis E virus. Emerg Microbes Infect 2012; 1:e17. [PMID: 26038426 PMCID: PMC3630916 DOI: 10.1038/emi.2012.7] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 03/21/2012] [Accepted: 04/08/2012] [Indexed: 02/07/2023]
Abstract
Hepatitis E virus (HEV), a single-stranded, positive-sense RNA virus, is responsible for acute hepatitis E epidemics in many developing countries, and the virus is also endemic in some industrialized countries. Hepatitis E is a recognized zoonotic disease, and several animal species, including pigs, are potential reservoirs for HEV. The genome of HEV contains three open reading frames (ORFs). ORF1 encodes the nonstructural proteins, ORF2 encodes the capsid protein, and ORF3 encodes a small multifunctional protein. The ORF2 and ORF3 proteins are translated from a single, bicistronic mRNA. The coding sequences for these two ORFs overlap each other, but neither overlaps with ORF1. Whereas the mechanisms underlying HEV replication are poorly understood, the construction of infectious viral clones, the identification of cell lines that support HEV replication, and the development of small animal models have allowed for more detailed study of the virus. As result of these advances, recently, our understanding of viral entry, genomic replication and viral egress has improved. Furthermore, the determination of the T=1 and T=3 structure of HEV virus-like particles has furthered our understanding of the replication of HEV. This article reviews the latest developments in the molecular biology of HEV with an emphasis on the genomic organization, the expression and function of genes, and the structure and replication of HEV.
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Affiliation(s)
- Dianjun Cao
- Center for Molecular Medicine and Infectious Diseases, Department of Biomedical Sciences and Pathobiology, Virginia Polytechnic Institute and State University (Virginia Tech) , Blacksburg, VA 24061-0913, USA
| | - Xiang-Jin Meng
- Center for Molecular Medicine and Infectious Diseases, Department of Biomedical Sciences and Pathobiology, Virginia Polytechnic Institute and State University (Virginia Tech) , Blacksburg, VA 24061-0913, USA
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Abstract
Hepatitis E virus (HEV) was discovered during the Soviet occupation of Afghanistan in the 1980s, after an outbreak of unexplained hepatitis at a military camp. A pooled faecal extract from affected soldiers was ingested by a member of the research team. He became sick, and the new virus (named HEV), was detected in his stool by electron microscopy. Subsequently, endemic HEV has been identified in many resource-poor countries. Globally, HEV is the most common cause of acute viral hepatitis. The virus was not initially thought to occur in developed countries, but recent reports have shown this notion to be mistaken. The aim of this Seminar is to describe recent discoveries regarding HEV, and how they have changed our understanding of its effect on human health worldwide.
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Affiliation(s)
- Nassim Kamar
- Department of Nephrology, Dialysis and Organ Transplantation, CHU Rangueil, Toulouse, France; Centre de Physiopathologie de Toulouse-Purpan, Toulouse, France; Université Paul Sabatier, Toulouse, France
| | - Richard Bendall
- Clinical Microbiology, Royal Cornwall Hospital Trust, Truro, UK
| | - Florence Legrand-Abravanel
- Centre de Physiopathologie de Toulouse-Purpan, Toulouse, France; Université Paul Sabatier, Toulouse, France; Department of Virology, CHU Purpan, Toulouse, France
| | - Ning-Shao Xia
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, Xiamen, China
| | - Samreen Ijaz
- Virus Reference Department, Microbiology Services-Colindale, Health Protection Agency, London, UK
| | - Jacques Izopet
- Centre de Physiopathologie de Toulouse-Purpan, Toulouse, France; Université Paul Sabatier, Toulouse, France; Department of Virology, CHU Purpan, Toulouse, France
| | - Harry R Dalton
- Cornwall Gastrointestinal Unit, Royal Cornwall Hospital Trust, Truro, UK; European Centre of Environment and Human Health, Peninsula College of Medicine and Dentistry, Universities of Exeter and Plymouth, Truro, UK.
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Zhang J, Li SW, Wu T, Zhao Q, Ng MH, Xia NS. Hepatitis E virus: neutralizing sites, diagnosis, and protective immunity. Rev Med Virol 2012; 22:339-49. [DOI: 10.1002/rmv.1719] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 03/13/2012] [Accepted: 03/29/2012] [Indexed: 12/25/2022]
Affiliation(s)
- Jun Zhang
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health; Xiamen University; Xiamen; China
| | - Shao-Wei Li
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health; Xiamen University; Xiamen; China
| | - Ting Wu
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health; Xiamen University; Xiamen; China
| | - Qinjian Zhao
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health; Xiamen University; Xiamen; China
| | - Mun-Hon Ng
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health; Xiamen University; Xiamen; China
| | - Ning-Shao Xia
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health; Xiamen University; Xiamen; China
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Chen C, Wang JCY, Zlotnick A. A kinase chaperones hepatitis B virus capsid assembly and captures capsid dynamics in vitro. PLoS Pathog 2011; 7:e1002388. [PMID: 22114561 PMCID: PMC3219723 DOI: 10.1371/journal.ppat.1002388] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 10/04/2011] [Indexed: 12/14/2022] Open
Abstract
The C-terminal domain (CTD) of Hepatitis B virus (HBV) core protein is involved in regulating multiple stages of the HBV lifecycle. CTD phosphorylation correlates with pregenomic-RNA encapsidation during capsid assembly, reverse transcription, and viral transport, although the mechanisms remain unknown. In vitro, purified HBV core protein (Cp183) binds any RNA and assembles aggressively, independent of phosphorylation, to form empty and RNA-filled capsids. We hypothesize that there must be a chaperone that binds the CTD to prevent self-assembly and nonspecific RNA packaging. Here, we show that HBV capsid assembly is stalled by the Serine Arginine protein kinase (SRPK) binding to the CTD, and reactivated by subsequent phosphorylation. Using the SRPK to probe capsids, solution and structural studies showed that SRPK bound to capsid, though the CTD is sequestered on the capsid interior. This result indicates transient CTD externalization and suggests that capsid dynamics could be crucial for directing HBV intracellular trafficking. Our studies illustrate the stochastic nature of virus capsids and demonstrate the appropriation of a host protein by a virus for a non-canonical function. A virus particle is a molecular machine that has evolved to self-assemble within the confines of a living cell. For hepatitis B virus (HBV), outside of a cell, the self-assembly process is very aggressive and consequently not specific for viral RNA. Here we show that HBV takes advantage of a host protein, SRPK, which acts like a molecular chaperone, to prevent the HBV core protein from binding RNA and to prevent the core protein from assembling at the wrong time and place. At the right time, SRPK can be removed in a regulated reaction to allow assembly. Once a virus is assembled, it must traffic to the right intracellular locale. Using SRPK, we show that HBV cores can transiently expose a segment of protein, normally inside the virus, that carries a signal for transport to the host nucleus. This is the first example we know of where a virus repurposes an enzyme for an alternative function. This sort of interplay between virus and host, where the virus hijacks and repurposes host proteins, is likely to be a common feature of viral infection.
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Affiliation(s)
- Chao Chen
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, United States of America
| | - Joseph Che-Yen Wang
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, United States of America
| | - Adam Zlotnick
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, United States of America
- * E-mail:
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65
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Serological diagnostics of hepatitis E virus infection. Virus Res 2011; 161:84-92. [PMID: 21704091 DOI: 10.1016/j.virusres.2011.06.006] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 06/03/2011] [Accepted: 06/07/2011] [Indexed: 12/15/2022]
Abstract
Development of accurate diagnostic assays for the detection of serological markers of hepatitis E virus (HEV) infection remains challenging. In the course of nearly 20 years after the discovery of HEV, significant progress has been made in characterizing the antigenic structure of HEV proteins, engineering highly immunoreactive diagnostic antigens, and devising efficient serological assays. However, many outstanding issues related to sensitivity and specificity of these assays in clinical and epidemiological settings remain to be resolved. Complexity of antigenic composition, viral genetic heterogeneity and varying epidemiological patterns of hepatitis E in different parts of the world present challenges to the refinement of HEV serological diagnostic assays. Development of antigens specially designed for the identification of serological markers specific to acute infection and of IgG anti-HEV specific to the convalescent phase of infection would greatly facilitate accurate identification of active, recent and past HEV infections.
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Structural basis for the neutralization and genotype specificity of hepatitis E virus. Proc Natl Acad Sci U S A 2011; 108:10266-71. [PMID: 21642534 DOI: 10.1073/pnas.1101309108] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Hepatitis E virus (HEV) causes acute hepatitis in humans, predominantly by contamination of food and water, and is characterized by jaundice and flu-like aches and pains. To date, no vaccines are commercially available to prevent the disease caused by HEV. Previously, we showed that a monoclonal antibody, 8C11, specifically recognizes a neutralizing conformational epitope on HEV genotype I. The antibody 8C11 blocks the virus-like particle from binding to and penetrating the host cell. Here, we report the complex crystal structure of 8C11 Fab with HEV E2s(I) domain at 1.9 Å resolution. The 8C11 epitopes on E2s(I) were identified at Asp(496)-Thr(499), Val(510)-Leu(514), and Asn(573)-Arg(578). Mutations and cell-model assays identified Arg(512) as the most crucial residue for 8C11 interaction with and neutralization of HEV. Interestingly, 8C11 specifically neutralizes HEV genotype I, but not the other genotypes. Because HEV type I and IV are the most abundant genotypes, to understand this specificity further we determined the structure of E2s(IV) at 1.79 Å resolution and an E2s(IV) complex with 8C11 model was generated. The comparison between the 8C11 complexes with type I and IV revealed the key residues that distinguish these two genotypes. Of particular interest, the residue at amino acid position 497 at the 8C11 epitope region of E2s is distinct among these two genotypes. Swapping this residue from one genotype to another inversed the 8C11 reactivity, demonstrating the essential role played by amino acid 497 in the genotype recognition. These studies may lead to the development of antibody-based drugs for the specific treatment against HEV.
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Ahmad I, Holla RP, Jameel S. Molecular virology of hepatitis E virus. Virus Res 2011; 161:47-58. [PMID: 21345356 PMCID: PMC3130092 DOI: 10.1016/j.virusres.2011.02.011] [Citation(s) in RCA: 181] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 02/13/2011] [Accepted: 02/13/2011] [Indexed: 12/15/2022]
Abstract
This review details the molecular virology of the hepatitis E virus (HEV). While replicons and in vitro infection systems have recently become available, a lot of information on HEV has been generated through comparisons with better-studied positive-strand RNA viruses and through subgenomic expression of viral open reading frames. These models are now being verified with replicon and infection systems. We provide here the current knowledge on the HEV genome and its constituent proteins--ORF1, ORF2 and ORF3. Based on the available information, we also modify the existing model of the HEV life cycle.
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Affiliation(s)
- Imran Ahmad
- Virology Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
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