1
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Zhang Y, Guo M, Zhang X, Zhang N, Zhu P, Wang H. Multiple optimizations of recombinant plasmid for improving expression of Hepatitis B core antigen in Escherichia coli. Protein Expr Purif 2022; 198:106127. [PMID: 35660658 DOI: 10.1016/j.pep.2022.106127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 05/28/2022] [Accepted: 05/31/2022] [Indexed: 02/07/2023]
Abstract
Hepatitis B core antigen (HBcAg) can self-assemble into virus-like particles (VLPs) when expressed in Escherichia coli. We optimized the different of the expression plasmid pBV220, including the ribosome bind site (RBS), spacer region, promoter and replication origin (ori), as well as the hbc gene dosage, to enhance HBcAg transcription and translation in E. coli. The optimized construct with a customized RBS6, 6 nt spacer, T7 promoter and pUCori significantly increased the levels of HBc36GFP fusion protein to 3.4-folds compared to the control. Thereafter, we substituted hbc36gfp gene with different copies of the hbc gene and tested the effects of gene dosage on HBcAg expression. The HBcAg-VLPs yield obtained using an engineered strain with three copies of hbc was 842.1 ± 46.8 μg/mL, which was 2.2-folds higher compared to that in the control strain. Thus, our study provides a simple and effective strategy for improving HBcAg expression in E. coli. Since the HBcAg-VLPs are promising carriers for presenting foreign antigen epitopes, an in vitro expression system that can generate high levels of HBcAg-VLPs can serve as a promising tool for developing novel HBV vaccines and drugs.
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Affiliation(s)
- Yi Zhang
- YishengBio Co., Ltd., Beijing, 102629, China
| | - Minli Guo
- YishengBio Co., Ltd., Beijing, 102629, China
| | - Xinyue Zhang
- Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, 100034, China
| | - Nan Zhang
- YishengBio Co., Ltd., Beijing, 102629, China.
| | - Ping Zhu
- Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100050, China.
| | - Hao Wang
- YishengBio Co., Ltd., Beijing, 102629, China.
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2
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Lefeuvre C, Le Guillou-Guillemette H, Ducancelle A. A Pleiotropic Role of the Hepatitis B Virus Core Protein in Hepatocarcinogenesis. Int J Mol Sci 2021; 22:ijms222413651. [PMID: 34948447 PMCID: PMC8707456 DOI: 10.3390/ijms222413651] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 12/18/2021] [Accepted: 12/19/2021] [Indexed: 02/07/2023] Open
Abstract
Chronic hepatitis B virus (HBV) infection is one of the most common factors associated with hepatocellular carcinoma (HCC), which is the sixth most prevalent cancer among all cancers worldwide. However, the pathogenesis of HBV-mediated hepatocarcinogenesis is unclear. Evidence currently available suggests that the HBV core protein (HBc) plays a potential role in the development of HCC, such as the HBV X protein. The core protein, which is the structural component of the viral nucleocapsid, contributes to almost every stage of the HBV life cycle and occupies diverse roles in HBV replication and pathogenesis. Recent studies have shown that HBc was able to disrupt various pathways involved in liver carcinogenesis: the signaling pathways implicated in migration and proliferation of hepatoma cells, apoptosis pathways, and cell metabolic pathways inducing the development of HCC; and the immune system, through the expression and production of proinflammatory cytokines. In addition, HBc can modulate normal functions of hepatocytes through disrupting human host gene expression by binding to promoter regions. This HBV protein also promotes HCC metastasis through epigenetic alterations, such as micro-RNA. This review focuses on the molecular pathogenesis of the HBc protein in HBV-induced HCC.
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Affiliation(s)
- Caroline Lefeuvre
- Laboratoire de Virologie, Département de Biologie des Agents Infectieux, CHU Angers, F-49000 Angers, France; (H.L.G.-G.); (A.D.)
- HIFIH Laboratory UPRES EA3859, SFR ICAT 4208, Angers University, F-49000 Angers, France
- Correspondence:
| | - Hélène Le Guillou-Guillemette
- Laboratoire de Virologie, Département de Biologie des Agents Infectieux, CHU Angers, F-49000 Angers, France; (H.L.G.-G.); (A.D.)
- HIFIH Laboratory UPRES EA3859, SFR ICAT 4208, Angers University, F-49000 Angers, France
| | - Alexandra Ducancelle
- Laboratoire de Virologie, Département de Biologie des Agents Infectieux, CHU Angers, F-49000 Angers, France; (H.L.G.-G.); (A.D.)
- HIFIH Laboratory UPRES EA3859, SFR ICAT 4208, Angers University, F-49000 Angers, France
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3
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Phosphorylation of the Arginine-Rich C-Terminal Domains of the Hepatitis B Virus (HBV) Core Protein as a Fine Regulator of the Interaction between HBc and Nucleic Acid. Viruses 2020; 12:v12070738. [PMID: 32650547 PMCID: PMC7412469 DOI: 10.3390/v12070738] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/02/2020] [Accepted: 07/03/2020] [Indexed: 02/08/2023] Open
Abstract
The morphogenesis of Hepatitis B Virus (HBV) viral particles is nucleated by the oligomerization of HBc protein molecules, resulting in the formation of an icosahedral capsid shell containing the replication-competent nucleoprotein complex made of the viral polymerase and the pre-genomic RNA (pgRNA). HBc is a phospho-protein containing two distinct domains acting together throughout the viral replication cycle. The N-terminal domain, (residues 1–140), shown to self-assemble, is linked by a short flexible domain to the basic C-terminal domain (residues 150–183) that interacts with nucleic acids (NAs). In addition, the C-terminal domain contains a series of phospho-acceptor residues that undergo partial phosphorylation and de-phosphorylation during virus replication. This highly dynamic process governs the homeostatic charge that is essential for capsid stability, pgRNA packaging and to expose the C-terminal domain at the surface of the particles for cell trafficking. In this review, we discuss the roles of the N-terminal and C-terminal domains of HBc protein during HBV morphogenesis, focusing on how the C-terminal domain phosphorylation dynamics regulate its interaction with nucleic acids throughout the assembly and maturation of HBV particles.
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van der Ree MH, Jansen L, Welkers MRA, Reesink HW, Feenstra KA, Kootstra NA. Deep sequencing identifies hepatitis B virus core protein signatures in chronic hepatitis B patients. Antiviral Res 2018; 158:213-225. [PMID: 30121196 DOI: 10.1016/j.antiviral.2018.08.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 08/10/2018] [Accepted: 08/13/2018] [Indexed: 11/16/2022]
Abstract
BACKGROUND We aimed to identify HBc amino acid differences between subgroups of chronic hepatitis B (CHB) patients. METHODS Deep sequencing of HBc was performed in samples of 89 CHB patients (42 HBeAg positive, 47 HBeAg negative). Amino acid types were compared using Sequence Harmony to identify subgroup specific sites between HBeAg-positive and -negative patients, and between patients with combined response and non-response to peginterferon/adefovir combination therapy. RESULTS We identified 54 positions in HBc where the frequency of appearing amino acids was significantly different between HBeAg-positive and -negative patients. In HBeAg negative patients, 22 positions in HBc were identified which differed between patients with treatment response and those with non-response. The fraction non-consensus sequence on selected positions was significantly higher in HBeAg-negative patients, and was negatively correlated with HBV DNA and HBsAg levels. CONCLUSIONS Sequence Harmony identified a number of amino acid changes associated with HBeAg-status and response to peginterferon/adefovir combination therapy.
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Affiliation(s)
- Meike H van der Ree
- Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, The Netherlands; Department of Experimental Immunology, Academic Medical Center, Amsterdam, The Netherlands
| | - Louis Jansen
- Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, The Netherlands; Department of Experimental Immunology, Academic Medical Center, Amsterdam, The Netherlands
| | - Matthijs R A Welkers
- Department of Medical Microbiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Hendrik W Reesink
- Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, The Netherlands; Department of Experimental Immunology, Academic Medical Center, Amsterdam, The Netherlands
| | - K Anton Feenstra
- Center for Integrative Bioinformatics VU (IBIVU), Department of Computer Science, Amsterdam Institute for Molecules, Medicine and Systems (AIMMS), VU University Amsterdam, The Netherlands
| | - Neeltje A Kootstra
- Department of Experimental Immunology, Academic Medical Center, Amsterdam, The Netherlands.
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5
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Diab A, Foca A, Fusil F, Lahlali T, Jalaguier P, Amirache F, N'Guyen L, Isorce N, Cosset FL, Zoulim F, Andrisani O, Durantel D. Polo-like-kinase 1 is a proviral host factor for hepatitis B virus replication. Hepatology 2017; 66:1750-1765. [PMID: 28445592 PMCID: PMC5658273 DOI: 10.1002/hep.29236] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 03/17/2017] [Accepted: 04/18/2017] [Indexed: 12/13/2022]
Abstract
Chronic hepatitis B virus (HBV) infection is a major risk factor for hepatocellular carcinoma (HCC) and current treatments for chronic hepatitis B and HCC are suboptimal. Herein, we identified cellular serine/threonine Polo-like-kinase 1 (PLK1) as a positive effector of HBV replication. The aim of this study was to demonstrate the proviral role of PLK1 in HBV biosynthesis and validate PLK1 inhibition a potential antiviral strategy. To this end, we employed physiologically relevant HBV infection models of primary human hepatocytes (PHHs) and differentiated HepaRG cells in conjunction with pharmacologic PLK1 inhibitors, small interfering RNA (siRNA)-mediated knockdown, and overexpression of constitutively active PLK1 (PLK1CA ). In addition, a humanized liver Fah-/- /Rag2-/- /Il2rg-/- (FRG) mouse model was used to determine the antiviral effect of PLK1 inhibitor BI-2536 on HBV infection in vivo. Finally, in vitro PLK1 kinase assays and site-directed mutagenesis were employed to demonstrate that HBV core protein (HBc) is a PLK1 substrate. We demonstrated that HBV infection activated cellular PLK1 in PHHs and differentiated HepaRG cells. PLK1 inhibition by BI-2536 or siRNA-mediated knockdown suppressed HBV DNA biosynthesis, whereas overexpression of PLK1CA increased it, suggesting that the PLK1 effects on viral biosynthesis are specific and that PLK1 is a proviral cellular factor. Significantly, BI-2536 administration to HBV-infected humanized liver FRG mice strongly inhibited HBV infection, validating PLK1 as an antiviral target in vivo. The proviral action of PLK1 is associated with the biogenesis of the nucleocapsid, as BI-2536 leads to its decreased intracellular formation/accumulation. In this respect, our studies identified HBc as a PLK1 substrate in vitro, and mapped PLK1 phosphorylation sites on this protein. CONCLUSION PLK1 is a proviral host factor that could be envisaged as a target for combined antiviral and antitumoral strategies against HBV infection and HBV-mediated carcinogenesis. (Hepatology 2017;66:1750-1765).
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Affiliation(s)
- Ahmed Diab
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
- Department of Basic Medical Sciences and Purdue Center for Cancer Research, Purdue University, West Lafayette, IN
| | - Adrien Foca
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
| | - Floriane Fusil
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
- CIRI-International Center for Infectiology Research, Team EVIR, INSERM, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univirsity of Lyon, Lyon, France
| | - Thomas Lahlali
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
| | - Pascal Jalaguier
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
| | - Fouzia Amirache
- CIRI-International Center for Infectiology Research, Team EVIR, INSERM, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univirsity of Lyon, Lyon, France
| | - Lia N'Guyen
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
| | - Nathalie Isorce
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
| | - François-Loïc Cosset
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
- CIRI-International Center for Infectiology Research, Team EVIR, INSERM, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Univirsity of Lyon, Lyon, France
| | - Fabien Zoulim
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
- Hepato-Gastroenterogy Unit, Croix-Rousse Hospital, Hospices Civils de Lyon, Lyon, France
- Labex DEVweCAN, Lyon, France
| | - Ourania Andrisani
- Department of Basic Medical Sciences and Purdue Center for Cancer Research, Purdue University, West Lafayette, IN
| | - David Durantel
- INSERM U1052, Cancer Research Center of Lyon, Lyon, France
- University of Lyon, Université Claude-Bernard, UMR_S1052, UCBL, Lyon, France
- Labex DEVweCAN, Lyon, France
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6
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Diab A, Foca A, Zoulim F, Durantel D, Andrisani O. The diverse functions of the hepatitis B core/capsid protein (HBc) in the viral life cycle: Implications for the development of HBc-targeting antivirals. Antiviral Res 2017; 149:211-220. [PMID: 29183719 DOI: 10.1016/j.antiviral.2017.11.015] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/08/2017] [Accepted: 11/17/2017] [Indexed: 12/14/2022]
Abstract
Virally encoded proteins have evolved to perform multiple functions, and the core protein (HBc) of the hepatitis B virus (HBV) is a perfect example. While HBc is the structural component of the viral nucleocapsid, additional novel functions for the nucleus-localized HBc have recently been described. These results extend for HBc, beyond its structural role, a regulatory function in the viral life cycle and potentially a role in pathogenesis. In this article, we review the diverse roles of HBc in HBV replication and pathogenesis, emphasizing how the unique structure of this protein is key to its various functions. We focus in particular on recent advances in understanding the significance of HBc phosphorylations, its interaction with host proteins and the role of HBc in regulating the transcription of host genes. We also briefly allude to the emerging niche for new direct-acting antivirals targeting HBc, known as Core (protein) Allosteric Modulators (CAMs).
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Affiliation(s)
- Ahmed Diab
- Department of Basic Medical Sciences and Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, 47907, USA; INSERM U1052, Cancer Research Center of Lyon (CRCL), Lyon, 69008, France; University of Lyon, Université Claude-Bernard (UCBL), UMR_S1052, UCBL, 69008, Lyon, France
| | - Adrien Foca
- INSERM U1052, Cancer Research Center of Lyon (CRCL), Lyon, 69008, France; University of Lyon, Université Claude-Bernard (UCBL), UMR_S1052, UCBL, 69008, Lyon, France
| | - Fabien Zoulim
- INSERM U1052, Cancer Research Center of Lyon (CRCL), Lyon, 69008, France; University of Lyon, Université Claude-Bernard (UCBL), UMR_S1052, UCBL, 69008, Lyon, France; Hepato-Gastroenterology Unit, Croix-Rousse Hospital, Hospices Civils de Lyon (HCL), 69002, Lyon, France; Labex DEVweCAN, 69008, Lyon, France
| | - David Durantel
- INSERM U1052, Cancer Research Center of Lyon (CRCL), Lyon, 69008, France; University of Lyon, Université Claude-Bernard (UCBL), UMR_S1052, UCBL, 69008, Lyon, France; Hepato-Gastroenterology Unit, Croix-Rousse Hospital, Hospices Civils de Lyon (HCL), 69002, Lyon, France.
| | - Ourania Andrisani
- Department of Basic Medical Sciences and Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, 47907, USA.
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7
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Complete and Incomplete Hepatitis B Virus Particles: Formation, Function, and Application. Viruses 2017; 9:v9030056. [PMID: 28335554 PMCID: PMC5371811 DOI: 10.3390/v9030056] [Citation(s) in RCA: 190] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 03/11/2017] [Accepted: 03/17/2017] [Indexed: 12/12/2022] Open
Abstract
Hepatitis B virus (HBV) is a para-retrovirus or retroid virus that contains a double-stranded DNA genome and replicates this DNA via reverse transcription of a RNA pregenome. Viral reverse transcription takes place within a capsid upon packaging of the RNA and the viral reverse transcriptase. A major characteristic of HBV replication is the selection of capsids containing the double-stranded DNA, but not those containing the RNA or the single-stranded DNA replication intermediate, for envelopment during virion secretion. The complete HBV virion particles thus contain an outer envelope, studded with viral envelope proteins, that encloses the capsid, which, in turn, encapsidates the double-stranded DNA genome. Furthermore, HBV morphogenesis is characterized by the release of subviral particles that are several orders of magnitude more abundant than the complete virions. One class of subviral particles are the classical surface antigen particles (Australian antigen) that contain only the viral envelope proteins, whereas the more recently discovered genome-free (empty) virions contain both the envelope and capsid but no genome. In addition, recent evidence suggests that low levels of RNA-containing particles may be released, after all. We will summarize what is currently known about how the complete and incomplete HBV particles are assembled. We will discuss briefly the functions of the subviral particles, which remain largely unknown. Finally, we will explore the utility of the subviral particles, particularly, the potential of empty virions and putative RNA virions as diagnostic markers and the potential of empty virons as a vaccine candidate.
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8
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Nuclear Import of Hepatitis B Virus Capsids and Genome. Viruses 2017; 9:v9010021. [PMID: 28117723 PMCID: PMC5294990 DOI: 10.3390/v9010021] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 01/17/2017] [Accepted: 01/17/2017] [Indexed: 02/07/2023] Open
Abstract
Hepatitis B virus (HBV) is an enveloped pararetrovirus with a DNA genome, which is found in an up to 36 nm-measuring capsid. Replication of the genome occurs via an RNA intermediate, which is synthesized in the nucleus. The virus must have thus ways of transporting its DNA genome into this compartment. This review summarizes the data on hepatitis B virus genome transport and correlates the finding to those from other viruses.
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9
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HBV maintains electrostatic homeostasis by modulating negative charges from phosphoserine and encapsidated nucleic acids. Sci Rep 2016; 6:38959. [PMID: 27958343 PMCID: PMC5154190 DOI: 10.1038/srep38959] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 11/14/2016] [Indexed: 12/22/2022] Open
Abstract
Capsid assembly and stability of hepatitis B virus (HBV) core protein (HBc) particles depend on balanced electrostatic interactions between encapsidated nucleic acids and an arginine-rich domain (ARD) of HBc in the capsid interior. Arginine-deficient ARD mutants preferentially encapsidated spliced viral RNA and shorter DNA, which can be fully or partially rescued by reducing the negative charges from acidic residues or serine phosphorylation of HBc, dose-dependently. Similarly, empty capsids without RNA encapsidation can be generated by ARD hyper-phosphorylation in insect, bacteria, and human hepatocytes. De-phosphorylation of empty capsids by phosphatase induced capsid disassembly. Empty capsids can convert into RNA-containing capsids by increasing HBc serine de-phosphorylation. In an HBV replicon system, we observed a reciprocal relationship between viral and non-viral RNA encapsidation, suggesting both non-viral RNA and serine-phosphorylation could serve as a charge balance buffer in maintaining electrostatic homeostasis. In addition, by comparing the biochemistry assay results between a replicon and a non-replicon system, we observed a correlation between HBc de-phosphorylation and viral replication. Balanced electrostatic interactions may be important to other icosahedral particles in nature.
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10
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Kim J, Wu J. A theoretical study of SRPK interaction with the flexible domains of hepatitis B capsids. Biophys J 2015; 107:1453-61. [PMID: 25229152 DOI: 10.1016/j.bpj.2014.07.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 06/27/2014] [Accepted: 07/15/2014] [Indexed: 12/22/2022] Open
Abstract
Hepatitis B virus (HBV) controls genome encapsidation and reverse transcription from a single-stranded RNA to a double-stranded DNA through the flexible C-terminal domain (CTD) of the capsid proteins. Although the microscopic structure of the nucleocapsid plays a critical role in the life cycle of HBV, the location of CTD residues at different stages of viral replication remains poorly understood. In this work, we report the radial distributions of individual amino-acid residues of the CTD tails for both empty and RNA-containing HBV capsids by using a coarse-grained model for the key biological components and the classical density functional theory. The density functional theory calculations reveal substantial exposure of the CTD residues outside the capsid, in particular when it is devoid of any nucleic materials. The outermost layer of the capsid surface mainly consists of residues from (170)Ser-(175)Arg of the CTD tails, i.e., the serine-arginine protein kinase binding motif. The theoretical description corroborates recent in vitro studies that show a transient CTD distribution captured by serine-arginine protein kinase binding. We have also investigated the nucleocapsid structural changes due to phosphorylation of serine residues and shown a correlation between the CTD location and the internal distribution of RNA segments.
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Affiliation(s)
- Jehoon Kim
- Department of Chemical and Environmental Engineering, University of California, Riverside, California
| | - Jianzhong Wu
- Department of Chemical and Environmental Engineering, University of California, Riverside, California.
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11
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Deroubaix A, Osseman Q, Cassany A, Bégu D, Ragues J, Kassab S, Lainé S, Kann M. Expression of viral polymerase and phosphorylation of core protein determine core and capsid localization of the human hepatitis B virus. J Gen Virol 2014; 96:183-195. [PMID: 25274856 DOI: 10.1099/vir.0.064816-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Biopsies from patients show that hepadnaviral core proteins and capsids - collectively called core - are found in the nucleus and cytoplasm of infected hepatocytes. In the majority of studies, cytoplasmic core localization is related to low viraemia while nuclear core localization is associated with high viral loads. In order to better understand the molecular interactions leading to core localization, we analysed transfected hepatoma cells using immune fluorescence microscopy. We observed that expression of core protein in the absence of other viral proteins led to nuclear localization of core protein and capsids, while expression of core in the context of the other viral proteins resulted in a predominantly cytoplasmic localization. Analysis of which viral partner was responsible for cytoplasmic retention indicated that the HBx, surface proteins and HBeAg had no impact but that the viral polymerase was the major determinant. Further analysis revealed that ϵ, an RNA structure to which the viral polymerase binds, was essential for cytoplasmic retention. Furthermore, we showed that core protein phosphorylation at Ser 164 was essential for the cytoplasmic core localization phenotype, which is likely to explain differences observed between individual cells.
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Affiliation(s)
- Aurélie Deroubaix
- Hepatitis Virus Diversity Research Programme, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg 2193, South Africa.,CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France.,Univ. de Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Quentin Osseman
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France.,Univ. de Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Aurélia Cassany
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France.,Univ. de Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Dominique Bégu
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France.,Univ. de Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Jessica Ragues
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France.,Univ. de Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Somar Kassab
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France.,Univ. de Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Sébastien Lainé
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France.,Univ. de Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France.,Université Montpellier 1, CPBS, UMR 5236 CNRS, Montpellier, France
| | - Michael Kann
- Univ. de Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France.,CHU de Bordeaux, Bordeaux, France.,CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
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12
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Liu D, Ni B, Wang L, Zhang M, Liu W, Wu Y. Hepatitis B virus core protein interacts with CD59 to promote complement-mediated liver inflammation during chronic hepatitis B virus infection. FEBS Lett 2013; 587:3314-20. [PMID: 24036449 DOI: 10.1016/j.febslet.2013.08.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 08/13/2013] [Accepted: 08/27/2013] [Indexed: 01/12/2023]
Abstract
The inflammatory response mediated by the immune system is the major cause of hepatitis B virus (HBV)-associated liver injury. Here, we identified CD59, as a novel HBc-interacting protein in hepatocytes by tandem affinity purification (TAP) screening. The expression of CD59 was markedly down-regulated in HBc-transfected HepG2 or HepG2.215 cells, which resulted in an upshift of hepatocyte sensitivity to membrane attack complex (MAC)-induced cell lysis. These results were consistent with the accumulation of MACs in the liver of HBV-infected patients. Additional analyses using laser confocal microscopy, quantitative PCR and flow cytometry revealed that CD59 was specifically translocated to the nucleus upon binding to HBc, which induced the down-regulation of CD59 on both the mRNA and protein levels.
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Affiliation(s)
- Dong Liu
- Institute of Immunology, PLA, The Third Military Medical University, Chongqing 400038, China
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Yu X, Jin L, Jih J, Shih C, Hong Zhou Z. 3.5Å cryoEM structure of hepatitis B virus core assembled from full-length core protein. PLoS One 2013; 8:e69729. [PMID: 24039702 PMCID: PMC3765168 DOI: 10.1371/journal.pone.0069729] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 06/12/2013] [Indexed: 12/14/2022] Open
Abstract
The capsid shell of infectious hepatitis B virus (HBV) is composed of 240 copies of a single protein called HBV core antigen (HBc). An atomic model of a core assembled from truncated HBc was determined previously by X-ray crystallography. In an attempt to obtain atomic structural information of HBV core in a near native, non-crystalline environment, we reconstructed a 3.5Å-resolution structure of a recombinant core assembled from full-length HBc by cryo electron microscopy (cryoEM) and derived an atomic model. The structure shows that the 240 molecules of full-length HBc form a core with two layers. The outer layer, composed of the N-terminal assembly domain, is similar to the crystal structure of the truncated HBc, but has three differences. First, unlike the crystal structure, our cryoEM structure shows no disulfide bond between the Cys61 residues of the two subunits within the dimer building block, indicating such bond is not required for core formation. Second, our cryoEM structure reveals up to four more residues in the linker region (amino acids 140-149). Third, the loops in the cryoEM structures containing this linker region in subunits B and C are oriented differently (~30° and ~90°) from their counterparts in the crystal structure. The inner layer, composed of the C-terminal arginine-rich domain (ARD) and the ARD-bound RNAs, is partially-ordered and connected with the outer layer through linkers positioned around the two-fold axes. Weak densities emanate from the rims of positively charged channels through the icosahedral three-fold and local three-fold axes. We attribute these densities to the exposed portions of some ARDs, thus explaining ARD's accessibility by proteases and antibodies. Our data supports a role of ARD in mediating communication between inside and outside of the core during HBV maturation and envelopment.
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Affiliation(s)
- Xuekui Yu
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, California, United States of America
- California NanoSystems Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Lei Jin
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, California, United States of America
- California NanoSystems Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Jonathan Jih
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, California, United States of America
- California NanoSystems Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Chiaho Shih
- Institute of Biomedical Sciences (IBMS), Academia Sinica, Taipei, Taiwan
| | - Z. Hong Zhou
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, California, United States of America
- California NanoSystems Institute, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
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Guo Y, Kang W, Lei X, Li Y, Xiang A, Liu Y, Zhao J, Zhang J, Yan Z. Hepatitis B viral core protein disrupts human host gene expression by binding to promoter regions. BMC Genomics 2012; 13:563. [PMID: 23088787 PMCID: PMC3484065 DOI: 10.1186/1471-2164-13-563] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 10/15/2012] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The core protein (HBc) of hepatitis B virus (HBV) has been implicated in the malignant transformation of chronically-infected hepatocytes and displays pleiotropic functions, including RNA- and DNA-binding activities. However, the mechanism by which HBc interacts with the human genome to exert effects on hepatocyte function remains unknown. This study investigated the distribution of HBc binding to promoters in the human genome and evaluated its effects on the related genes' expression. RESULTS Whole-genome chromatin immunoprecipitation microarray (ChIP-on-chip) analysis was used to identify HBc-bound human gene promoters. Gene Ontology and pathway analyses were performed on related genes. The quantitative polymerase chain reaction assay was used to verify ChIP-on-chip results. Five novel genes were selected for luciferase reporter assay evaluation to assess the influence of HBc promoter binding. The HBc antibody immunoprecipitated approximately 3100 human gene promoters. Among these, 1993 are associated with known biological processes, and 2208 regulate genes with defined molecular functions. In total, 1286 of the related genes mediate primary metabolic processes, and 1398 encode proteins with binding activity. Sixty-four of the promoters regulate genes related to the mitogen-activated protein kinase (MAPK) pathways, and 41 regulate Wnt/beta-catenin pathway genes. The reporter gene assay indicated that HBc binding up-regulates proto-oncogene tyrosine-protein kinase (SRC), type 1 insulin-like growth factor receptor (IGF1R), and neurotrophic tyrosine kinase receptor 2 (NTRK2), and down-regulates v-Ha-ras Harvey rat sarcoma viral oncogene (HRAS). CONCLUSION HBc has the ability to bind a large number of human gene promoters, and can disrupt normal host gene expression. Manipulation of the transcriptional profile in HBV-infected hepatocytes may represent a key pathogenic mechanism of HBV infection.
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Affiliation(s)
- Yanhai Guo
- State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, Fourth Military Medical University, 169 West Changle Road, Xi’an, 710032, China
| | - Wei Kang
- Department of Clinical Laboratory, Affiliated Hospital of Xi’an Medical University, Xi’an, 710077, China
| | - Xiaoying Lei
- State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, Fourth Military Medical University, 169 West Changle Road, Xi’an, 710032, China
| | - Yongnian Li
- Department of Infectious Diseases, 323 Hospital, Xi’an, 710000, China
| | - An Xiang
- State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, Fourth Military Medical University, 169 West Changle Road, Xi’an, 710032, China
| | - Yonglan Liu
- State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, Fourth Military Medical University, 169 West Changle Road, Xi’an, 710032, China
| | - Jinrong Zhao
- State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, Fourth Military Medical University, 169 West Changle Road, Xi’an, 710032, China
| | - Ju Zhang
- State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, Fourth Military Medical University, 169 West Changle Road, Xi’an, 710032, China
| | - Zhen Yan
- State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, Fourth Military Medical University, 169 West Changle Road, Xi’an, 710032, China
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Zhu Y, Jin Y, Cai X, Bai X, Chen M, Chen T, Wang J, Qian G, Gu J, Li J, Tu H. Hepatitis B Virus Core Protein Variations Differ in Tumor and Adjacent Nontumor Tissues from Patients with Hepatocellular Carcinoma. Intervirology 2012; 55:29-35. [DOI: 10.1159/000322832] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 11/11/2010] [Indexed: 12/25/2022] Open
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16
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Ning X, Nguyen D, Mentzer L, Adams C, Lee H, Ashley R, Hafenstein S, Hu J. Secretion of genome-free hepatitis B virus--single strand blocking model for virion morphogenesis of para-retrovirus. PLoS Pathog 2011; 7:e1002255. [PMID: 21966269 PMCID: PMC3178560 DOI: 10.1371/journal.ppat.1002255] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 07/21/2011] [Indexed: 12/18/2022] Open
Abstract
As a para-retrovirus, hepatitis B virus (HBV) is an enveloped virus with a double-stranded (DS) DNA genome that is replicated by reverse transcription of an RNA intermediate, the pregenomic RNA or pgRNA. HBV assembly begins with the formation of an “immature” nucleocapsid (NC) incorporating pgRNA, which is converted via reverse transcription within the maturing NC to the DS DNA genome. Only the mature, DS DNA-containing NCs are enveloped and secreted as virions whereas immature NCs containing RNA or single-stranded (SS) DNA are not enveloped. The current model for selective virion morphogenesis postulates that accumulation of DS DNA within the NC induces a “maturation signal” that, in turn, triggers its envelopment and secretion. However, we have found, by careful quantification of viral DNA and NCs in HBV virions secreted in vitro and in vivo, that the vast majority of HBV virions (over 90%) contained no DNA at all, indicating that NCs with no genome were enveloped and secreted as empty virions (i.e., enveloped NCs with no DNA). Furthermore, viral mutants bearing mutations precluding any DNA synthesis secreted exclusively empty virions. Thus, viral DNA synthesis is not required for HBV virion morphogenesis. On the other hand, NCs containing RNA or SS DNA were excluded from virion formation. The secretion of DS DNA-containing as well as empty virions on one hand, and the lack of secretion of virions containing single-stranded (SS) DNA or RNA on the other, prompted us to propose an alternative, “Single Strand Blocking” model to explain selective HBV morphogenesis whereby SS nucleic acid within the NC negatively regulates NC envelopment, which is relieved upon second strand DNA synthesis. Hepatitis B virus (HBV), an important global human pathogen and the main cause of liver cancer worldwide, is classified as a para-retrovirus, as it replicates by reverse transcription, i.e., copying of RNA to DNA, like retroviruses. However, different from retroviruses that are RNA viruses replicating via a DNA intermediate, HBV is a DNA virus that replicates through an RNA intermediate. Like retroviruses, HBV initially packages an RNA copy of its genome into intracellular subviral particles. However, complete HBV virions contain only a double-stranded (DS) DNA. The long-standing model to explain this selective presence of DS DNA in HBV virions postulates that DS DNA synthesis is required to trigger virion secretion. We have found, however, that virion secretion does not require any DNA synthesis. Rather, the presence of the single-stranded RNA (or the single-stranded DNA intermediate of reverse transcription) negatively regulates virion formation. These results thus change the prevailing paradigm in understanding HBV morphogenesis and also have important implications for virus assembly in general. Furthermore, they raise the important question regarding the role of empty HBV virions identified here in viral replication and pathogenesis.
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Affiliation(s)
- Xiaojun Ning
- Department of Microbiology and Immunology, The Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - David Nguyen
- Department of Microbiology and Immunology, The Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Laura Mentzer
- Department of Microbiology and Immunology, The Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Christina Adams
- Department of Microbiology and Immunology, The Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Hyunwook Lee
- Department of Microbiology and Immunology, The Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
- Division of Infectious Diseases, Department of Medicine, The Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Robert Ashley
- Department of Microbiology and Immunology, The Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
- Division of Infectious Diseases, Department of Medicine, The Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Susan Hafenstein
- Department of Microbiology and Immunology, The Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
- Division of Infectious Diseases, Department of Medicine, The Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Jianming Hu
- Department of Microbiology and Immunology, The Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
- * E-mail:
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17
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Nuclear export and import of human hepatitis B virus capsid protein and particles. PLoS Pathog 2010; 6:e1001162. [PMID: 21060813 PMCID: PMC2965763 DOI: 10.1371/journal.ppat.1001162] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Accepted: 09/24/2010] [Indexed: 12/21/2022] Open
Abstract
It remains unclear what determines the subcellular localization of hepatitis B virus (HBV) core protein (HBc) and particles. To address this fundamental issue, we have identified four distinct HBc localization signals in the arginine rich domain (ARD) of HBc, using immunofluorescence confocal microscopy and fractionation/Western blot analysis. ARD consists of four tight clustering arginine-rich subdomains. ARD-I and ARD-III are associated with two co-dependent nuclear localization signals (NLS), while ARD-II and ARD-IV behave like two independent nuclear export signals (NES). This conclusion is based on five independent lines of experimental evidence: i) Using an HBV replication system in hepatoma cells, we demonstrated in a double-blind manner that only the HBc of mutant ARD-II+IV, among a total of 15 ARD mutants, can predominantly localize to the nucleus. ii) These results were confirmed using a chimera reporter system by placing mutant or wild type HBc trafficking signals in the heterologous context of SV40 large T antigen (LT). iii) By a heterokaryon or homokaryon analysis, the fusion protein of SV40 LT-HBc ARD appeared to transport from nuclei of transfected donor cells to nuclei of recipient cells, suggesting the existence of an NES in HBc ARD. This putative NES is leptomycin B resistant. iv) We demonstrated by co-immunoprecipitation that HBc ARD can physically interact with a cellular factor TAP/NXF1 (Tip-associated protein/nuclear export factor-1), which is known to be important for nuclear export of mRNA and proteins. Treatment with a TAP-specific siRNA strikingly shifted cytoplasmic HBc to nucleus, and led to a near 7-fold reduction of viral replication, and a near 10-fold reduction in HBsAg secretion. v) HBc of mutant ARD-II+IV was accumulated predominantly in the nucleus in a mouse model by hydrodynamic delivery. In addition to the revised map of NLS, our results suggest that HBc could shuttle rapidly between nucleus and cytoplasm via a novel TAP-dependent NES.
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18
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Martinez-Izquierdo J, Hohn T. Cauliflower mosaic virus coat protein is phosphorylated in vitro by a virion-associated protein kinase. Proc Natl Acad Sci U S A 2010; 84:1824-8. [PMID: 16593818 PMCID: PMC304533 DOI: 10.1073/pnas.84.7.1824] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A protein kinase has been found to be associated with particles of the plant virus cauliflower mosaic virus. This protein kinase can phosphorylate endogenous viral capsid proteins in vitro and exchange substrates with casein kinase type II. The activity is not affected by cAMP but is enhanced considerably by ADP. The cofactor is either Mn(2+) or Mg(2+), and the phosphate donor is either ATP or GTP. Serine and threonine residues are phosphorylated.
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19
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Testing the balanced electrostatic interaction hypothesis of hepatitis B virus DNA synthesis by using an in vivo charge rebalance approach. J Virol 2009; 84:2340-51. [PMID: 20015989 DOI: 10.1128/jvi.01666-09] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Previously, a charge balance hypothesis was proposed to explain hepatitis B virus (HBV) capsid stability, assembly, RNA encapsidation, and DNA replication. This hypothesis emphasized the importance of a balanced electrostatic interaction between the positive charge from the arginine-rich domain (ARD) of the core protein (HBc) and the negative charge from the encapsidated nucleic acid. It remains unclear if any of the negative charge involved in this electrostatic interaction could come from the HBc protein per se, in addition to the encapsidated nucleic acid. HBc ARD IV mutant 173GG and ARD II mutant 173RR/R157A/R158A are arginine deficient and replication defective. Not surprisingly, the replication defect of ARD IV mutant 173GG can be rescued by restoring positively charged amino acids at the adjacent positions 174 and 175. However, most interestingly, it can be at least partially rescued by reducing negatively charged residues in the assembly domain, such as by glutamic acid-to-alanine (E-to-A) substitutions at position 46 or 117 and to a much lesser extent at position 113. Similar results were obtained for ARD II mutant 173RR/R157A/R158A. These amino acids are located on the inner surfaces of HBc icosahedral particles, and their acidic side chains point toward the capsid interior. For HBV DNA synthesis, the relative amount of positive versus negative charge in the electrostatic interactions is more important than the absolute amount of positive or negative charge. These results support the concept that balanced electrostatic interaction is important during the viral life cycle.
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20
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Lu L, Liu W, Yang X. A novel method for characterizing the multi-functional C-terminal domain of the Hepadnavirus core protein. J Virol Methods 2009; 158:195-8. [PMID: 19428590 DOI: 10.1016/j.jviromet.2009.01.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2008] [Revised: 01/19/2009] [Accepted: 01/22/2009] [Indexed: 10/21/2022]
Abstract
The Hepadnavirus core protein is a viral structural protein with an N-terminal self-assembling domain and a C-terminal protamine-like arginine-rich domain (ARD). The ARD contains four clusters of arginine residues involved in RNA binding, genome DNA synthesis, and nuclear localization. Characterization of the multi-functions of ARD has been impeded due to the insoluble nature of the core protein expressed in vitro. A GST (glutathione-S-transferase) and ARD fusion protein, GST-ARD, was expressed and purified in this study. Gel mobility shift assays using purified GST-ARD fusion proteins demonstrated that, similar to protamine, the ARD domain of the core protein bound to oligonucleotides without sequence preference. In vitro affinity chromatography binding assays showed further that the ARD bound to tested random plasmid DNA in a sequence-independent manner. The GST-ARD fusion protein-based approach can be employed further to study other biochemical properties of the core protein.
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Affiliation(s)
- Liqun Lu
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China.
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21
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Broos K, Vanlandschoot P, Maras M, Robbens J, Leroux-Roels G, Guisez Y. Expression, purification and characterization of full-length RNA-free hepatitis B core particles. Protein Expr Purif 2007; 54:30-7. [PMID: 17387023 DOI: 10.1016/j.pep.2007.02.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Revised: 01/25/2007] [Accepted: 02/05/2007] [Indexed: 11/19/2022]
Abstract
The nucleocapsid or core particle of the hepatitis B virus has become one of the favourite recombinant vaccine carriers for foreign peptides, proteins and stimulatory oligonucleotides. The core protein consists of three regions: an N-terminal, a central and a C-terminal region that can accommodate the addition or insertion of the foreign sequences. The protamine-like C-terminal region that binds host RNA randomly during recombinant particle formation is often truncated. It is commonly thought that these truncations do not affect particle assembly. Recent studies have demonstrated that the C-terminal domains mediate a glycosaminoglycan-dependent attachment of nucleocapsids to the plasma membranes of host cells. This interaction might well contribute to the immunogenicity of nucleocapsids. Testing the hypothesis that full-length particles might be safer and superior for the induction of an immune response against the nucleocapsids and inserted sequences, requires the availability of purified particles. In this report, we detail a novel method for the synthesis and purification of full-length core particles essentially free of RNA from Escherichia coli.
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Affiliation(s)
- Katleen Broos
- Laboratory of Plant Physiology, Department of Biology, 171 Groenenborgerlaan, Building U, 6th Floor, CGB University of Antwerp, 2020 Antwerpen, Belgium
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22
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Le Pogam S, Chua PK, Newman M, Shih C. Exposure of RNA templates and encapsidation of spliced viral RNA are influenced by the arginine-rich domain of human hepatitis B virus core antigen (HBcAg 165-173). J Virol 2005; 79:1871-87. [PMID: 15650211 PMCID: PMC544126 DOI: 10.1128/jvi.79.3.1871-1887.2005] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Previously, human hepatitis B virus (HBV) mutant 164, which has a truncation at the C terminus of the HBV core antigen (HBcAg), was speculated to secrete immature genomes. For this study, we further characterized mutant 164 by different approaches. In addition to the 3.5-kb pregenomic RNA (pgRNA), the mutant preferentially encapsidated the 2.2-kb or shorter species of spliced RNA, which can be reverse transcribed into double-stranded DNA before virion secretion. We observed that mutant 164 produced less 2.2-kb spliced RNA than the wild type. Furthermore, it appeared to produce at least two different populations of capsids: one encapsidated a nuclease-sensitive 3.5-kb pgRNA while the other encapsidated a nuclease-resistant 2.2-kb spliced RNA. In contrast, the wild-type core-associated RNA appeared to be resistant to nuclease. When arginines and serines were systematically restored at the truncated C terminus, the core-associated DNA and nuclease-resistant RNA gradually increased in both size and signal intensity. Full protection of encapsidated pgRNA from nuclease was observed for HBcAg 1-171. A full-length positive-strand DNA phenotype requires positive charges at amino acids 172 and 173. Phosphorylation at serine 170 is required for optimal RNA encapsidation and a full-length positive-strand DNA phenotype. RNAs encapsidated in Escherichia coli by capsids of HBcAg 154, 164, and 167, but not HBcAg 183, exhibited nuclease sensitivity; however, capsid instability after nuclease treatment was observed only for HBcAg 164 and 167. A new hypothesis is proposed here to highlight the importance of a balanced charge density for capsid stability and intracapsid anchoring of RNA templates.
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Affiliation(s)
- Sophie Le Pogam
- Department of Pathology, WHO Collaborating Center for Tropical Diseases, and Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555-0609, USA
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23
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Watts NR, Conway JF, Cheng N, Stahl SJ, Belnap DM, Steven AC, Wingfield PT. The morphogenic linker peptide of HBV capsid protein forms a mobile array on the interior surface. EMBO J 2002; 21:876-84. [PMID: 11867516 PMCID: PMC125892 DOI: 10.1093/emboj/21.5.876] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Many capsid proteins have peptides that influence their assembly. In hepatitis B virus capsid protein, the peptide STLPETTVV, linking the shell-forming 'core' domain and the nucleic acid-binding 'protamine' domain, has such a role. We have studied its morphogenic properties by permuting its sequence, substituting it with an extraneous peptide, deleting it to directly fuse the core and protamine domains and assembling core domain dimers with added linker peptides. The peptide was found to be necessary for the assembly of protamine domain-containing capsids, although its size-determining effect tolerates some modifications. Although largely invisible in a capsid crystal structure, we could visualize linker peptides by cryo-EM difference imaging: they emerge on the inner surface and extend from the capsid protein dimer interface towards the adjacent symmetry axis. A closely sequence-similar peptide in cellobiose dehydrogenase, which has an extended conformation, offers a plausible prototype. We propose that linker peptides are attached to the capsid inner surface as hinged struts, forming a mobile array, an arrangement with implications for morphogenesis and the management of encapsidated nucleic acid.
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Affiliation(s)
- Norman R. Watts
- Protein Expression Laboratory and Laboratory of Structural Biology, National Institute of Arthritis, Musculoskeletal and Skin Diseases, Building 50, Room 1517, 50 South drive MSC 8025, National Institutes of Health, Bethesda, MD 20892-8025, USA and Institut de Biologie Structurale J.-P.Ebel, 41 rue Jules Horowitz, F-38027 Grenoble, France Corresponding author e-mail:
| | - James F. Conway
- Protein Expression Laboratory and Laboratory of Structural Biology, National Institute of Arthritis, Musculoskeletal and Skin Diseases, Building 50, Room 1517, 50 South drive MSC 8025, National Institutes of Health, Bethesda, MD 20892-8025, USA and Institut de Biologie Structurale J.-P.Ebel, 41 rue Jules Horowitz, F-38027 Grenoble, France Corresponding author e-mail:
| | - Naiqian Cheng
- Protein Expression Laboratory and Laboratory of Structural Biology, National Institute of Arthritis, Musculoskeletal and Skin Diseases, Building 50, Room 1517, 50 South drive MSC 8025, National Institutes of Health, Bethesda, MD 20892-8025, USA and Institut de Biologie Structurale J.-P.Ebel, 41 rue Jules Horowitz, F-38027 Grenoble, France Corresponding author e-mail:
| | - Stephen J. Stahl
- Protein Expression Laboratory and Laboratory of Structural Biology, National Institute of Arthritis, Musculoskeletal and Skin Diseases, Building 50, Room 1517, 50 South drive MSC 8025, National Institutes of Health, Bethesda, MD 20892-8025, USA and Institut de Biologie Structurale J.-P.Ebel, 41 rue Jules Horowitz, F-38027 Grenoble, France Corresponding author e-mail:
| | - David M. Belnap
- Protein Expression Laboratory and Laboratory of Structural Biology, National Institute of Arthritis, Musculoskeletal and Skin Diseases, Building 50, Room 1517, 50 South drive MSC 8025, National Institutes of Health, Bethesda, MD 20892-8025, USA and Institut de Biologie Structurale J.-P.Ebel, 41 rue Jules Horowitz, F-38027 Grenoble, France Corresponding author e-mail:
| | - Alasdair C. Steven
- Protein Expression Laboratory and Laboratory of Structural Biology, National Institute of Arthritis, Musculoskeletal and Skin Diseases, Building 50, Room 1517, 50 South drive MSC 8025, National Institutes of Health, Bethesda, MD 20892-8025, USA and Institut de Biologie Structurale J.-P.Ebel, 41 rue Jules Horowitz, F-38027 Grenoble, France Corresponding author e-mail:
| | - Paul T. Wingfield
- Protein Expression Laboratory and Laboratory of Structural Biology, National Institute of Arthritis, Musculoskeletal and Skin Diseases, Building 50, Room 1517, 50 South drive MSC 8025, National Institutes of Health, Bethesda, MD 20892-8025, USA and Institut de Biologie Structurale J.-P.Ebel, 41 rue Jules Horowitz, F-38027 Grenoble, France Corresponding author e-mail:
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Salhi S, Messageot F, Carlier D, Jean-Jean O, Rossignol JM. Identification of a cellular protein specifically interacting with the precursor of the hepatitis B e antigen. J Viral Hepat 2001; 8:169-73. [PMID: 11380793 DOI: 10.1046/j.1365-2893.2001.00293.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
In hepatitis B virus (HBV) the precore gene encodes a protein from which derives P22, the precursor of the mature secreted hepatitis B virus e antigen (HBeAg). Circumstantial evidences suggest that HBeAg and/or its precursor P22 are important for establishing persistent infection. Although P22 is essentially present in the secretory pathway, a substantial fraction has been found in the cytosol. In order to get new insights into the biological function of P22, we looked for cellular proteins which could strongly associate with this protein. Using immunoprecipitation studies on human cell extracts, we found that a non-secreted cellular protein of about 32 kDa (P32) bound with a high specificity to P22. P32 associated neither with HBeAg nor with the viral core protein P21 which exhibits the same amino acids sequence as P22 but is N-terminally shorter by 10 residues. We also demonstrated that this interaction depended on the presence of the P22 C-terminal domain. Our data argues for a potential biological function of P22.
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Affiliation(s)
- S Salhi
- Laboratoire de Génétique des Virus, UPR 9053-CNRS, Avenue de la Terrasse, 91198 Gif sur Yvette, France
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25
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Bock CT, Schwinn S, Locarnini S, Fyfe J, Manns MP, Trautwein C, Zentgraf H. Structural organization of the hepatitis B virus minichromosome. J Mol Biol 2001; 307:183-96. [PMID: 11243813 DOI: 10.1006/jmbi.2000.4481] [Citation(s) in RCA: 260] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The replicative intermediate of hepatitis B virus (HBV), the covalently closed, circular DNA, is organized into minichromosomes in the nucleus of the infected cell by histone and non-histone proteins. In this study we investigated the architecture of the HBV minichromosome in more detail. In contrast to cellular chromatin the nucleosomal spacing of the HBV minichromosome has been shown to be unusually reduced by approximately 10 %. A potential candidate responsible for an alteration in the chromatin structure of the HBV minichromosome is the HBV core protein. The HBV core protein has been implicated in the nuclear targeting process of the viral genome. The association of the HBV core protein with nuclear HBV replicative intermediates could strengthen this role. Our findings, confirmed by in vivo and in vitro experiments indicate that HBV core protein is a component of the HBV minichromosome, binds preferentially to HBV double-stranded DNA, and its binding results in a reduction of the nucleosomal spacing of the HBV nucleoprotein complexes by 10 %. From this model of the HBV minichromosome we propose that the HBV core protein may have an impact on the nuclear targeting of the HBV genome and be involved in viral transcription by regulating the nucleosomal arrangement of the HBV regulatory elements, probably in a positive manner.
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Affiliation(s)
- C T Bock
- Department of Gastroenterology and Hepatology, Medical School Hannover, Hannover, Germany.
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26
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Lott L, Beames B, Notvall L, Lanford RE. Interaction between hepatitis B virus core protein and reverse transcriptase. J Virol 2000; 74:11479-89. [PMID: 11090144 PMCID: PMC112427 DOI: 10.1128/jvi.74.24.11479-11489.2000] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Previous mutagenesis studies with hepatitis B virus (HBV) suggest that continued interactions with core are required for several steps in genomic replication. To examine core-polymerase (Pol) interactions, insect cells were coinfected with baculovirus constructs that independently expressed core and Pol. The results demonstrated several features with implications that core plays an interactive role with HBV Pol: (i) core coprecipitated with constructs expressing full-length Pol as well as the terminal protein (TP), reverse transcriptase (RT) and RNase H domains of Pol, independently; (ii) coprecipitation of core was not dependent on the presence of an epsilon stem-loop sequence; and (iii) core-Pol complexes migrated as intact capsid particles, as detected by sucrose gradient analysis. To analyze the structural and sequence requirements of core in recognition of Pol, a series of core mutants with two- to four-amino-acid insertions or carboxy-terminal deletions were assessed for Pol interaction. The results indicated that capsid formation is required but not sufficient for interaction with Pol and that the TP and RT domains of Pol have different requirements for interaction with core. To map the core binding sites on Pol, a panel of amino- and carboxy-terminal deletion mutants of the TP and RT domains of Pol were analyzed for interaction with core. At least three separate core binding sites on Pol were detected. This analysis begins to define basic requirements for core-Pol interactions, but further study is necessary to delineate the effects of these interactions on encapsidation and genome replication.
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Affiliation(s)
- L Lott
- Department of Virology and Immunology, Southwest Regional Primate Research Center, Southwest Foundation for Biomedical Research, San Antonio, Texas 78227, USA
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27
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Zlotnick A, Cheng N, Stahl SJ, Conway JF, Steven AC, Wingfield PT. Localization of the C terminus of the assembly domain of hepatitis B virus capsid protein: implications for morphogenesis and organization of encapsidated RNA. Proc Natl Acad Sci U S A 1997; 94:9556-61. [PMID: 9275161 PMCID: PMC23216 DOI: 10.1073/pnas.94.18.9556] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The capsid protein of hepatitis B virus, consisting of an "assembly" domain (residues 1-149) and an RNA-binding "protamine" domain (residues 150-183), assembles from dimers into icosahedral capsids of two different sizes. The C terminus of the assembly domain (residues 140-149) functions as a morphogenetic switch, longer C termini favoring a higher proportion of the larger capsids, it also connects the protamine domain to the capsid shell. We now have defined the location of this peptide in capsids assembled in vitro by engineering a mutant assembly domain with a single cysteine at its C terminus (residue 150), labeling it with a gold cluster and visualizing the cluster by cryo-electron microscopy. The labeled protein is unimpaired in its ability to form capsids. Our density map reveals a single undecagold cluster under each fivefold and quasi-sixfold vertex, connected to sites at either end of the undersides of the dimers. Considering the geometry of the vertices, the C termini must be more crowded at the fivefolds. Thus, a bulky C terminus would be expected to favor formation of the larger (T = 4) capsids, which have a greater proportion of quasi-sixfolds. Capsids assembled by expressing the full-length protein in Escherichia coli package bacterial RNAs in amounts equivalent to the viral pregenome. Our density map of these capsids reveals a distinct inner shell of density-the RNA. The RNA is connected to the protein shell via the C-terminal linkers and also makes contact around the dimer axes.
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Affiliation(s)
- A Zlotnick
- Protein Expression Laboratory, National Institute of Arthritis, Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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28
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Sällberg M, Townsend K, Chen M, O'Dea J, Banks T, Jolly DJ, Chang SM, Lee WT, Milich DR. Characterization of humoral and CD4+ cellular responses after genetic immunization with retroviral vectors expressing different forms of the hepatitis B virus core and e antigens. J Virol 1997; 71:5295-303. [PMID: 9188598 PMCID: PMC191766 DOI: 10.1128/jvi.71.7.5295-5303.1997] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The humoral and CD4+ cellular immune responses in mice following genetic immunization with three retroviral vectors encoding different forms of hepatitis B virus core antigen (HBcAg) and e antigen (HBeAg) were analyzed. The retroviral vectors induced expression of intracellular HBcAg (HBc[3A4]), secreted HBeAg (HBe[5A2]), or an intracellular HBcAg-neomycin phosphoryltransferase fusion protein (HBc-NEO[6A3]). Specific antibody levels and immunoglobulin G isotype restriction were highly dependent on both the host major histocompatibility complex and the transferred gene. Humoral and CD4+ cellular HBcAg and/or HBeAg (HBc/eAg)-specific immune responses following retroviral vector immunization were of a lower magnitude but followed the same characteristics compared with those after immunization with HBc/eAg in adjuvant. Two factors influenced the humoral responses. First, in vivo depletion of CD8+ cells in HBc-NEO[6A3]-immunized H-2k mice abrogated both HBcAg-specific antibodies and in vitro-detectable cytotoxic T lymphocytes. Second, priming of H-2b mice with an HBc/eAg-derived T-helper (Th) peptide in adjuvant prior to retroviral vector immunization greatly enhanced the HBc/eAg-specific humoral responses to all three vectors, suggesting that insufficient HBc/eAg-specific CD4+ Th-cell priming limits the humoral responses. In conclusion, direct injection of retroviral vectors seems to be effective in priming HBc/eAg-specific CD8+ but comparatively inefficient in priming CD4+ Th cells and subsequently specific antibodies. However, the limited HBc/eAg-specific CD4+ cell priming can effectively be circumvented by prior administration of a recombinant or synthetic form of HBc/eAg in adjuvant.
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Affiliation(s)
- M Sällberg
- Department of Molecular Biology, Scripps Research Institute, La Jolla, California 92037, USA.
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29
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Zlotnick A, Cheng N, Conway JF, Booy FP, Steven AC, Stahl SJ, Wingfield PT. Dimorphism of hepatitis B virus capsids is strongly influenced by the C-terminus of the capsid protein. Biochemistry 1996; 35:7412-21. [PMID: 8652518 DOI: 10.1021/bi9604800] [Citation(s) in RCA: 231] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Hepatitis B virus (HBV) is an enveloped virus with an icosahedral capsid. Its homodimeric capsid protein ("core antigen") assembles into particles of two sizes, one with T = 3 icosahedral symmetry (90 dimers) and the other with T = 4 symmetry (120 dimers). We have investigated this assembly process in vitro, using a variety of purified, bacterially expressed, capsid proteins. All of our constructs lacked the predominantly basic C-terminal 34 amino acids of the full-length capsid protein (183 amino acids) and were further truncated to terminate at specific points between residues 138 and 149. While the smallest construct (138 residues) did not assemble into capsids, those terminating at residue 140, and beyond, assembled into mixtures of T = 3 and T = 4 particles. The two kinds of capsids could be separated on sucrose gradients and did not interconvert upon protracted storage. The proportion of T = 3 capsids, assayed by sucrose gradient fractionation, analytical ultracentrifugation, and cryoelectron microscopy, was found to increase systematically with larger deletions from the C-terminus. The variant terminating at residue 149 formed approximately 5% of T = 3 capsids, while the 140-residue protein produced approximately 85% of this isomorph. For the 147-residue capsid protein, the structures of both capsids were determined to 17 A resolution by three-dimensional reconstruction of cryoelectron micrographs. In these density maps, the boundaries of the constituent dimers can be clearly seen and the quaternary structures of the two capsids compared. The arrangement of dimers around their icosahedral five-fold axes is almost identical, whereas the quasi-six-fold arrangements of dimers are distinctly different.
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Affiliation(s)
- A Zlotnick
- Laboratory of Structural Biology, National Institute of Arthritis, Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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30
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Abstract
Replication of the hepadnavirus DNA genome is accomplished via reverse transcription of an intermediate, pregenomic RNA molecule. This process is likely to be carried out by a virally encoded, multifunctional polymerase which possesses DNA- and RNA-dependent DNA polymerase and RNase H activities. However, the nature of the product(s) of the polymerase gene predicted to mediate these functions is unclear. Biochemical studies of the polymerase protein(s) have been limited by its apparent low abundance in virus particles and, until recently, the inability to express active polymerase protein(s) heterologously. We have used activity gel assays to detect DNA- and RNA-dependent DNA polymerase activities associated with highly purified duck hepatitis B virus (DHBV) core particles (S. M. Oberhaus and J. E. Newbold, J. Virol. 67:6558-6566, 1993). Now we report that the same approach identifies a 35-kDa RNase H activity in association with highly purified DHBV core particles and crude preparations of virions from DHBV-infected ducks and woodchuck hepatitis virus-infected woodchucks. This is the first report of the detection of an hepadnavirus-associated RNase H activity. Its apparent size is smaller than any of the DNA polymerase activities that we detected previously and significantly smaller than the full-length protein predicted from the polymerase open reading frame (p85 for DHBV). These data suggest that the viral polymerase and RNase H activities are separable and that these enzymes may coordinate their activities in vivo by forming a complex.
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Affiliation(s)
- S M Oberhaus
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina at Chapel Hill 27599-7290, USA
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31
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Guidotti LG, Martinez V, Loh YT, Rogler CE, Chisari FV. Hepatitis B virus nucleocapsid particles do not cross the hepatocyte nuclear membrane in transgenic mice. J Virol 1994; 68:5469-75. [PMID: 8057429 PMCID: PMC236947 DOI: 10.1128/jvi.68.9.5469-5475.1994] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Transgenic mice that express the hepatitis B virus core protein were used to examine factors that influence the intracellular localization of nucleocapsid particles in the primary hepatocyte in vivo. In this model, viral nucleocapsid particles are strictly localized to the nucleus of the hepatocyte except when the nuclear membrane dissolves during cell division, at which time they enter the cytoplasm. The cytoplasmic nucleocapsid particles do not reenter the nucleus, however, when the nuclear membrane re-forms after cell division. The data support the notion that nucleocapsid particles can form de novo within the nucleus, and they suggest that performed nucleocapsid particles cannot be transported across the intact nuclear membrane in either direction. The results imply that nucleocapsid disassembly is probably required for entry of the hepadnaviral genome into the nucleus, and they question the role of the intranuclear viral nucleocapsid particle during the viral life cycle.
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Affiliation(s)
- L G Guidotti
- Department of Molecular and Experimental Medicine, Scripps Research Institute, La Jolla, California 92037
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32
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Chen Y, Robinson WS, Marion PL. Selected mutations of the duck hepatitis B virus P gene RNase H domain affect both RNA packaging and priming of minus-strand DNA synthesis. J Virol 1994; 68:5232-8. [PMID: 8035519 PMCID: PMC236467 DOI: 10.1128/jvi.68.8.5232-5238.1994] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The genome of all hepadnaviruses has an open reading frame called the P gene, which encodes a polypeptide of 90 to 97 kDa. The product or products of this P gene are involved in multiple functions of the viral life cycle. These functions include a priming activity which initiates minus-strand DNA synthesis, a polymerase activity which synthesizes DNA by using either RNA or DNA templates (reverse transcriptase), a nuclease activity which degrades the RNA strand of RNA-DNA hybrids (RNase H), and involvement in packaging the RNA pregenome into nucleocapsids. In a previous study, we found that a single point mutation at position 711 in the duck hepatitis B virus (DHBV) P gene product RNase H domain prevented viral RNA packaging. In the present experiments, we have mutated additional conserved amino acids in the DHBV RNase H domain and examined the ability of viral genomes containing these mutations to package RNA and replicate viral DNA. Charged and sulfur group amino acids adjacent to Cys-711 were mutated. None of these mutants was defective in either RNA packaging or viral replication. We also tested a number of mutations on the basis of common elements in the crystal structures of Escherichia coli and human immunodeficiency virus reverse transcriptase RNase H enzymes and on the basis of the similarities of their amino acid sequences to those of the RNase H domains of DHBV and HBV. Our results revealed that the entire beta 4 strand and amino acids Leu-712, Leu-697, and Val-719 in the putative hydrophobic cores of the beta 4, alpha A, and alpha B regions, respectively, are involved in pregenomic RNA encapsidation. This suggests that the basic structure of the RNase H domain in the DHBV P gene product is required for viral RNA packaging. We used the in vitro DHBV minus-strand DNA priming system developed by Wang and Seeger (G.-H. Wang and C. Seeger, Cell 71:663-670, 1992) to test the effect of RNase H packaging mutations on P gene product enzymatic activity. While all packaging-defective mutants tested maintained DNA priming activity, levels were decreased 5- to 20-fold compared with that of the wild-type genome. This observation suggests that the hepadnavirus RNase H domain plays a role in optimizing priming of minus-strand DNA synthesis.
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Affiliation(s)
- Y Chen
- Department of Medicine, Stanford University School of Medicine, California 94305
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33
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Abstract
A high level of anti-HCV is generally associated with viral replication and the number of recognized epitopes appears to be correlated with the viral charge. Nevertheless, the absence of detectable antibodies in about 60% of patients during the acute phase of the disease and in 10% of chronically infected (generally immunocompromised subjects) are heavy handicaps for HCV serology. Moreover, low levels of anti-HCV antibodies can persist after complete recovery, and HCV viremia does not appear to be associated with the presence of a special antibody specificity. The immunoblots presented as 'confirmatory test' always appear to be less sensitive than the screening tests and therefore are unable to discriminate between post-infection antibodies and false-positive reactions, as rare as they can be. In these cases, as in non-responder patients, PCR appears essential. The possible reasons of immune response limitations and the possible improvements of HCV serology are discussed.
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Affiliation(s)
- J Pillot
- WHO Centre for Reference and Research on Viral Hepatitis, Institut Pasteur, Paris, France
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34
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Yang W, Guo J, Ying Z, Hua S, Dong W, Chen H. Capsid assembly and involved function analysis of twelve core protein mutants of duck hepatitis B virus. J Virol 1994; 68:338-45. [PMID: 8254745 PMCID: PMC236293 DOI: 10.1128/jvi.68.1.338-345.1994] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The roles of different regions of the duck hepatitis B virus (DHBV) core protein on viral capsid assembly and related functions were examined. Twelve deletion and insertion mutations which covered 80% of the DHBV C open reading frame were constructed and expressed in Escherichia coli. The N-terminal region (amino acids 3 to 66) of DHBV core protein was important for its tertiary structure and function in E. coli. The expressed core mutants without this region apparently inhibited E. coli growth. The results of transmission electron microscopy of E. coli thin sections, capsid agarose gel, and sucrose gradient sedimentation demonstrated that a few DHBV core mutants with insertion in the N terminus and deletion in the C terminus retained the ability to form core-like particles in E. coli. However, other mutations in most of N-terminal and central regions strongly inhibited the self-assembly ability of DHBV core protein in E. coli. In addition, the mutant with a C-terminal region deletion (amino acids 181 to 228) lost most of the nucleic acid-binding activity of the DHBV core protein.
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Affiliation(s)
- W Yang
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, Tiantan, Beijing
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35
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Wen YM. Hepatitis B virus precore and core gene mutations in chronic hepatitis B and hepatocellular carcinoma patients. J Intern Med 1993; 234:441-5. [PMID: 8228787 DOI: 10.1111/j.1365-2796.1993.tb00775.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Y M Wen
- Department of Molecular Virology, Shanghai Medical University, People's Republic of China
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36
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Affiliation(s)
- T Uchida
- Department of Pathology, Nihon University School of Medicine, Tokyo, Japan
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37
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Zhou S, Standring DN. Hepatitis B virus capsid particles are assembled from core-protein dimer precursors. Proc Natl Acad Sci U S A 1992; 89:10046-50. [PMID: 1438193 PMCID: PMC50274 DOI: 10.1073/pnas.89.21.10046] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Our studies on the assembly of hepatitis B virus capsids or core particles in Xenopus oocytes have demonstrated that unassembled p21.5 core proteins ("free p21.5") provide a pool of low-molecular-mass precursors for core-particle assembly. Here we have characterized this material. Free p21.5 sedimented through gradients of 3-25% sucrose (wt/vol) as a single protein species of approximately 40 kDa, corresponding to a p21.5 dimer. On nonreducing SDS/polyacrylamide gels, free p21.5 migrated as disulfide-linked p21.5 dimeric species of 35 and 37 kDa. Truncated core proteins lacking most or all of the 36-amino acid protamine region at the p21.5 carboxyl terminus were also found to behave as disulfide-linked dimers with appropriately reduced molecular masses. Our experiments failed to reveal monomeric core proteins or stable intermediates between dimers and capsids along the assembly pathway. We conclude that hepatitis B virus core particles are most likely assembled by aggregating 90 (or possibly 180) disulfide-linked p21.5 dimers. We discuss similarities between the assembly of hepatitis B virus capsids and simple T = 3 plant virus and bacteriophage structures.
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Affiliation(s)
- S Zhou
- Hormone Research Institute, University of California, San Francisco 94143-0534
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38
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Hatton T, Zhou S, Standring DN. RNA- and DNA-binding activities in hepatitis B virus capsid protein: a model for their roles in viral replication. J Virol 1992; 66:5232-41. [PMID: 1501273 PMCID: PMC289076 DOI: 10.1128/jvi.66.9.5232-5241.1992] [Citation(s) in RCA: 158] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The hepatitis B virus capsid or core protein (p21.5) binds nucleic acid through a carboxy-terminal protamine region that contains nucleic acid-binding motifs organized into four repeats (I to IV). Using carboxy-terminally truncated proteins expressed in Escherichia coli, we detected both RNA- and DNA-binding activities within the repeats. RNA-binding and packaging activity, assessed by resolving purified E. coli capsids on agarose gels and disclosing their RNA content with ethidium bromide, required only the proximal repeat I (RRRDRGRS). Strikingly, a mutant in which four Arg residues replaced repeat I was competent to package RNA, demonstrating that Arg residues drive RNA binding. In contrast, probing immobilized core proteins with 32P-nucleic acid revealed an activity which (i) required more of the protamine region (repeats I and II), (ii) appeared to bind DNA better than RNA, and (iii) was apparently modulated by phosphorylation in p21.5 derived from Xenopus oocytes. Deletion analysis suggested that this activity may depend on an SPXX-type DNA-binding motif in repeat II. Similar motifs found in repeats III and IV may also function to bind DNA. On the basis of these observations, together with a reinterpretation of recent studies showing that capsid protein mutants cause defects in viral genome replication, we propose a model suggesting that hepadnavirus capsid proteins participate directly in the intracapsid reverse transcription of RNA into DNA. In this model, repeat I binds RNA whereas the distal repeats are progressively recruited to bind elongating DNA strands. The latter motifs may be required for replication to be energetically feasible.
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Affiliation(s)
- T Hatton
- Hormone Research Institute, University of California, San Francisco 94143-0534
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39
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Nassal M. Conserved cysteines of the hepatitis B virus core protein are not required for assembly of replication-competent core particles nor for their envelopment. Virology 1992; 190:499-505. [PMID: 1529550 DOI: 10.1016/0042-6822(92)91242-m] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Replication of hepatitis B virus (HBV) proceeds by reverse transcription of an RNA intermediate inside the viral nucleocapsid formed by the core protein. This protein contains four Cys residues which occur at equivalent positions in the core proteins of all known mammalian hepadnaviruses, suggesting that they might be of structural and/or functional importance. The four His residues of the core protein are located strikingly close to the three N-proximal cysteines. This arrangement is likewise conserved and might indicate the presence of an unconventional Cys-His box element similar to that required for nucleic acid binding in all retroviral NC proteins. In order to test the potential involvement of the core protein cysteines in virus assembly, we transiently expressed in HuH7 cells a mutant HBV genome encoding a core protein in which all cysteines are replaced by serine residues and analyzed the formation of replication-competent cores using the endogenous polymerase reaction. The mutant genome yielded products that were nearly indistinguishable from those produced by a corresponding wild-type genome, virtually ruling out the presence of a functional Cys-His box element in the hepadnaviral core protein. Density gradient analysis showed that the mutant cores were enveloped, though the efficiency of envelopment and/or the stability of the mutant enveloped particles was lowered compared to the wild-type. These data indicate that none of the steps in the viral life cycle from reverse transcription to envelopment was principally impaired. The conservedness of the cysteines might then be related to virus infectivity rather than replication; alternatively, the Cys residues might not be important for the core protein itself, but for the alternative C gene product HBeAg.
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Affiliation(s)
- M Nassal
- Zentrum für Molekulare Biologie, Universität Heidelberg, Germany
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40
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Nassal M. The arginine-rich domain of the hepatitis B virus core protein is required for pregenome encapsidation and productive viral positive-strand DNA synthesis but not for virus assembly. J Virol 1992; 66:4107-16. [PMID: 1602535 PMCID: PMC241213 DOI: 10.1128/jvi.66.7.4107-4116.1992] [Citation(s) in RCA: 363] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Assembly of replication-competent hepatitis B virus (HBV) nucleocapsids requires the interaction of the core protein, the P protein, and the RNA pregenome. The core protein contains an arginine-rich C-terminal domain which is dispensable for particle formation in heterologous expression systems. Using transient expression in HuH7 cells of a series of C-terminally truncated core proteins, I examined the functional role of this basic region in the context of a complete HBV genome. All variants containing at least the 144 N-terminal amino acids were assembly competent, but efficient pregenome encapsidation was observed only with variants consisting of 164 or more amino acids. These data indicate that one function of the arginine-rich region is to provide the interactions between core protein and RNA pregenome. However, in cores from the variant ending with amino acid 164, the production of complete positive-strand DNA was drastically reduced. Moreover, almost all positive-strand DNA originated from in situ priming, whereas in wild-type particles, this type of priming not supporting the formation of relaxed circular DNA (RC-DNA) accounted for about one half of the positive strands. Further C-terminal residues to position 173 restored RC-DNA formation, and the corresponding variant did not differ from the full-length core protein in all assays used. The observation that RNA encapsidation and formation of RC-DNA can be genetically separated suggests that the core protein, via its basic C-terminal region, also acts as an essential auxiliary component in HBV replication, possibly like a histone, or like a single-stranded-DNA-binding protein. In contrast to their importance for HBV replication, sequences beyond amino acid 164 were not required for the formation of enveloped virions. Since particles from variant 164 did not contain mature DNA genomes, a genome maturation signal is apparently not required for HBV nucleocapsid envelopment.
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Affiliation(s)
- M Nassal
- Zentrum für Molekulare Biologie, Universität Heidelberg, Germany
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41
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Zhou S, Yang SQ, Standring DN. Characterization of hepatitis B virus capsid particle assembly in Xenopus oocytes. J Virol 1992; 66:3086-92. [PMID: 1560538 PMCID: PMC241070 DOI: 10.1128/jvi.66.5.3086-3092.1992] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Little is known about the assembly of the 28-nm nucleocapsid or core particle of hepatitis B virus. Here we show that this assembly process can be reconstituted in Xenopus oocytes injected with a synthetic mRNA encoding the hepatitis B virus capsid protein (p21.5). Injected oocytes produce both a nonparticulate p21.5 species (free p21.5) and capsid particles. We describe rapid and simple methods for fractionating these species on a small scale either with step gradients of 10 to 60% (wt/vol) sucrose or by centrifugation to pellet the particles, and we characterize the oocyte core particles. Free p21.5 exhibits chemical and physical properties distinctly different from those of particles. Free p21.5 is partially cleaved by proteinase K, whereas core particles are almost completely resistant to cleavage. This suggests that the carboxyl-terminal protamine region, the main target for proteases within p21.5, is exposed in free p21.5 but faces the interior of the p21.5 core particle. Finally, pulse-chase experiments demonstrated that free p21.5 can be chased almost quantitatively into core particles, establishing that free p21.5 is fully competent to form particles and represents an assembly intermediate on the pathway for core particle formation. However, core particle assembly appears very dependent on p21.5 concentration and is rapidly compromised if the p21.5 concentration is lowered. The advantages of oocytes for studying assembly are discussed.
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Affiliation(s)
- S Zhou
- Hormone Research Institute, University of California, San Francisco 94143-0534
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42
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Chen Y, Robinson WS, Marion PL. Naturally occurring point mutation in the C terminus of the polymerase gene prevents duck hepatitis B virus RNA packaging. J Virol 1992; 66:1282-7. [PMID: 1309904 PMCID: PMC240843 DOI: 10.1128/jvi.66.2.1282-1287.1992] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
A duck hepatitis B virus (DHBV) genome cloned from a domestic duck from the People's Republic of China has been sequenced and exhibits no variation in sequences known to be important in viral replication or generation of gene products. Intrahepatic transfection of a dimer of this viral genome into ducklings did not result in viremia or any sign of virus infection, indicating that the genome was defective. Functional analysis of this mutant genome, performed by transfecting the DNA into a chicken hepatoma cell line capable of replicating wild-type virus, indicated that viral RNA is not encapsidated. However, virus core protein is made and can assemble into particles in the absence of encapsidation of viral nucleic acid. Using genetic approaches, it was determined that a change of cysteine to tyrosine in position 711 in the polymerase (P) gene C terminus led to this RNA-packaging defect. By site-directed mutagenesis, it was found that while substitution of Cys-711 with tryptophan also abolished packaging, substitution with methionine did not affect packaging or viral replication. Therefore, Cys-711, which is conserved in all published sequences of DHBV, may not be involved in a disulfide bridge structure essential to viral RNA packaging or replication. Our results, showing that a missense mutation in the region of the DHBV polymerase protein thought to be primarily the RNase H domain results in packaging deficiency, support the previous findings that multiple regions of the complex hepadnaviral polymerase protein may be required for viral RNA packaging.
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MESH Headings
- Amino Acid Sequence
- Animals
- Blotting, Southern
- Capsid/analysis
- Capsid/physiology
- Cell Line
- Chickens
- Cloning, Molecular
- DNA, Viral/genetics
- DNA-Directed RNA Polymerases/genetics
- Ducks
- Genes, Viral
- Genome, Viral
- Hepatitis B Virus, Duck/enzymology
- Hepatitis B Virus, Duck/genetics
- Mutagenesis, Site-Directed
- Mutation
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Ribonuclease H/genetics
- Transfection
- Viral Core Proteins/analysis
- Viral Core Proteins/physiology
- Virus Replication
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Affiliation(s)
- Y Chen
- Department of Medicine, Stanford University School of Medicine, California 94305-5107
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43
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Kniskern PJ, Miller WJ. Hepatitis B vaccines: blueprints for vaccines of the future. BIOTECHNOLOGY (READING, MASS.) 1992; 20:177-204. [PMID: 1600381 DOI: 10.1016/b978-0-7506-9265-6.50014-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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44
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Machida A, Ohnuma H, Tsuda F, Yoshikawa A, Hoshi Y, Tanaka T, Kishimoto S, Akahane Y, Miyakawa Y, Mayumi M. Phosphorylation in the carboxyl-terminal domain of the capsid protein of hepatitis B virus: evaluation with a monoclonal antibody. J Virol 1991; 65:6024-30. [PMID: 1717713 PMCID: PMC250268 DOI: 10.1128/jvi.65.11.6024-6030.1991] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The capsid protein of hepatitis B virus (p21c) is made of 183 amino acids coded for by the C gene. By using p21c isolated from Dane particles (hepatitis B virus) as an immunogen, a monoclonal antibody (no. 2212) which recognized an epitope dependent on the phosphorylation of p21c was raised. The binding of no. 2212 antibody to authentic p21c was completely inhibited by a synthetic undecapeptide with a sequence of RRRSQSPRRRR, representing amino acids 165 to 175 of p21c, only when the peptide was phosphorylated. Either or both of Ser-168 and Ser-170 were phosphorylated in p21c in vivo, therefore, and contributed to the manifestation of the epitope. No. 2212 antibody bound to p21c from core particles derived from Dane particles or hepatocellular carcinoma tissues (PLC/342) propagated in nude mice but did not bind to p21c from core particles expressed in Escherichia coli or yeast cells, indicating different states of phosphorylation in them. Nonphosphorylated p21c showed a higher affinity for the viral DNA than did phosphorylated p21c. Since the serum from an asymptomatic carrier, with a high titer for antibody to hepatitis B core antigen, specifically bound to phosphorylated undecapeptide (amino acids 165 to 175), the epitope would stimulate humoral antibody responses in the human host.
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Affiliation(s)
- A Machida
- Department of Immunology, Kitasato Institute, Tokyo, Japan
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45
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Terré S, Petit MA, Bréchot C. Defective hepatitis B virus particles are generated by packaging and reverse transcription of spliced viral RNAs in vivo. J Virol 1991; 65:5539-43. [PMID: 1895403 PMCID: PMC249055 DOI: 10.1128/jvi.65.10.5539-5543.1991] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Generation of replicative defective viruses is frequently observed during viral infections. We now report that encapsidation and reverse transcription of spliced viral RNA is an additional mechanism for synthesis of defective viral particles. We have investigated the in vivo synthesis of a spliced hepatitis B virus (HBV) RNA. By using the polymerase chain reaction with different sets of primers on DNA purified from infected livers and the HepG2 HBV cell line, we detected a subgenomic HBV DNA complementary to the spliced viral RNA. Its nucleotide sequence was found to be identical to that previously described for the spliced RNA. This HBV RNA is packaged and reverse transcribed in vivo, the cDNA being incorporated into circulating particles. This finding establishes the synthesis of spliced HBV RNA in vivo and indicates that its reverse transcription can give rise to defective viruses.
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Affiliation(s)
- S Terré
- INSERM U75, Centre Hospitalo-Universitaire Necker, Paris, France
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46
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Affiliation(s)
- J Y Lau
- Royal Free Hospital School of Medicine, London
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47
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Jeng KS, Hu CP, Chang CM. Differential formation of disulfide linkages in the core antigen of extracellular and intracellular hepatitis B virus core particles. J Virol 1991; 65:3924-7. [PMID: 2041102 PMCID: PMC241430 DOI: 10.1128/jvi.65.7.3924-3927.1991] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Our understanding of the assembly of hepatitis B virus is still very limited. We present evidence to demonstrate that the HBc antigen formed oligomers through disulfide linkages in the extracellular hepatitis B virus core (HBc) particles. However, the intracellular HBV core particles did not contain disulfide-linked HBc antigens. Furthermore, the extracellular particles which had disulfide bonds were more stable than intracellular particles at pH 7.5 and 10 and in 3 M NaCl and 4 M urea. These data suggest that the formation of disulfide bonds in the HBc antigen is important for the integrity of the viral core particles.
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Affiliation(s)
- K S Jeng
- Graduate Institute of Microbiology and Immunology, National Yang-Ming Medical College, Taipei, Taiwan, Republic of China
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48
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Ferrari C, Bertoletti A, Penna A, Cavalli A, Valli A, Missale G, Pilli M, Fowler P, Giuberti T, Chisari FV. Identification of immunodominant T cell epitopes of the hepatitis B virus nucleocapsid antigen. J Clin Invest 1991; 88:214-22. [PMID: 1711541 PMCID: PMC296022 DOI: 10.1172/jci115280] [Citation(s) in RCA: 180] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Several lines of experimental evidence suggest that inclusion of core sequences in the hepatitis B vaccine may represent a feasible strategy to increase the efficacy of the vaccination. In order to identify immunodominant core epitopes, peripheral blood T cells purified from 23 patients with acute hepatitis B and different HLA haplotypes were tested with a panel of 18 short synthetic peptides (15 to 20 amino acids [AA]) covering the entire core region. All patients except one showed a strong T cell proliferative response to a single immunodominant 20 amino acid sequence located within the aminoterminal half of the core molecule. Two additional important sequences were also identified at the aminoterminal end and within the carboxyterminal half of the core molecule. These sequences were able to induce significant levels of T cell proliferation in 69 and 73% of the patients studied, respectively. T cell response to these epitopes was HLA class II restricted. The observations that (a) polyclonal T cell lines produced by PBMC stimulation with native HBcAg were specifically reactive with the relevant peptides and that (b) polyclonal T cell lines produced with synthetic peptides could be restimulated with native HBcAg, provide evidence that AA sequences contained within the synthetic peptides represent real products of the intracellular processing of the native core molecule. In conclusion, the identification of immunodominant T cell epitopes within the core molecule provides the molecular basis for the design of alternative and hopefully more immunogenic vaccines.
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Affiliation(s)
- C Ferrari
- Cattedra Malattie Infettive, Università di Parma, Italy
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49
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Affiliation(s)
- D Ganem
- Department of Microbiology and Immunology, University of California Medical Center, San Francisco 94143-0503
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50
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Schröder CH, Zentgraf H. Hepatitis B virus related hepatocellular carcinoma: chronicity of infection--the opening to different pathways of malignant transformation? BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1032:137-56. [PMID: 2175655 DOI: 10.1016/0304-419x(90)90001-h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- C H Schröder
- Institut für Virusforschung, Deutsches Krebsforschungszentrum, Heidelberg, F.R.G
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