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Majeed NA, Hitawala AA, Heller T, Koh C. Diagnosis of HDV: From virology to non-invasive markers of fibrosis. Liver Int 2023; 43 Suppl 1:31-46. [PMID: 36621853 PMCID: PMC10329733 DOI: 10.1111/liv.15515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 11/25/2022] [Accepted: 01/04/2023] [Indexed: 01/10/2023]
Abstract
Hepatitis D viral infection in humans is a disease that requires the establishment of hepatitis B, relying on hepatitis B surface Ag and host cellular machinery to replicate and propagate the infection. Since its discovery in 1977, substantial progress has been made to better understand the hepatitis D viral life cycle, pathogenesis and modes of transmission along with expanding on clinical knowledge related to prevention, diagnosis, monitoring and treatment. The availability of serologic diagnostic assays for hepatitis D infection has evolved over time with current widespread availability, improved detection and standardized reporting. With human migration, the epidemiology of hepatitis D infection has changed over time. Thus, the ability to use diagnostic assays remains essential to monitor the global impact of hepatitis D infection. Separately, while liver biopsy remains the gold standard for the staging of this rapidly progressive and severe form of chronic viral hepatitis, there is an unmet need for clinical monitoring of chronic hepatitis D infection for management of progressive disease. Thus, exploration of the utility of non-invasive fibrosis markers in hepatitis D is ongoing. In this review, we discuss the virology, the evolution of diagnostics and the development of non-invasive markers for the detection and monitoring of fibrosis in patients with hepatitis D infection.
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Affiliation(s)
- Nehna Abdul Majeed
- Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Asif Ali Hitawala
- Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Theo Heller
- Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Christopher Koh
- Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
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2
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Ueda K, Suwanmanee Y. ATP5B Is an Essential Factor for Hepatitis B Virus Entry. Int J Mol Sci 2022; 23:ijms23179570. [PMID: 36076968 PMCID: PMC9455612 DOI: 10.3390/ijms23179570] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 08/18/2022] [Accepted: 08/22/2022] [Indexed: 11/16/2022] Open
Abstract
Elucidation of the factors responsible for hepatitis B virus (HBV) is extremely important in order to understand the viral life cycle and pathogenesis, and thereby explore potential anti-HBV drugs. The recent determination that sodium taurocholate co-transporting peptide (NTCP) is an essential molecule for the HBV entry into cells led to the development of an HBV infection system in vitro using a human hepatocellular carcinoma (HCC) cell line expressing NTCP; however, the precise mechanism of HBV entry is still largely unknown, and thus it may be necessary to elucidate all the molecules involved. Here, we identified ATP5B as another essential factor for HBV entry. ATP5B was expressed on the cell surface of the HCC cell lines and bound with myristoylated but not with non-myristoylated preS1 2-47, which supported the notion that ATP5B is involved in the HBV entry process. Knockdown of ATP5B in NTCP-expressing HepG2 cells, which allowed HBV infection, reduced HBV infectivity with less cccDNA formation. Taken together, these results strongly suggested that ATP5B is an essential factor for HBV entry into the cells.
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Kakkanas A, Karamichali E, Koufogeorgou EI, Kotsakis SD, Georgopoulou U, Foka P. Targeting the YXXΦ Motifs of the SARS Coronaviruses 1 and 2 ORF3a Peptides by In Silico Analysis to Predict Novel Virus-Host Interactions. Biomolecules 2022; 12:1052. [PMID: 36008946 PMCID: PMC9405953 DOI: 10.3390/biom12081052] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 07/21/2022] [Accepted: 07/25/2022] [Indexed: 02/08/2023] Open
Abstract
The emerging SARS-CoV and SARS-CoV-2 belong to the family of "common cold" RNA coronaviruses, and they are responsible for the 2003 epidemic and the current pandemic with over 6.3 M deaths worldwide. The ORF3a gene is conserved in both viruses and codes for the accessory protein ORF3a, with unclear functions, possibly related to viral virulence and pathogenesis. The tyrosine-based YXXΦ motif (Φ: bulky hydrophobic residue-L/I/M/V/F) was originally discovered to mediate clathrin-dependent endocytosis of membrane-spanning proteins. Many viruses employ the YXXΦ motif to achieve efficient receptor-guided internalisation in host cells, maintain the structural integrity of their capsids and enhance viral replication. Importantly, this motif has been recently identified on the ORF3a proteins of SARS-CoV and SARS-CoV-2. Given that the ORF3a aa sequence is not fully conserved between the two SARS viruses, we aimed to map in silico structural differences and putative sequence-driven alterations of regulatory elements within and adjacently to the YXXΦ motifs that could predict variations in ORF3a functions. Using robust bioinformatics tools, we investigated the presence of relevant post-translational modifications and the YXXΦ motif involvement in protein-protein interactions. Our study suggests that the predicted YXXΦ-related features may confer specific-yet to be discovered-functions to ORF3a proteins, significant to the new virus and related to enhanced propagation, host immune regulation and virulence.
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Affiliation(s)
- Athanassios Kakkanas
- Laboratory of Molecular Virology, Hellenic Pasteur Institute, 115-21 Athens, Greece; (A.K.); (E.K.); (E.I.K.); (U.G.)
| | - Eirini Karamichali
- Laboratory of Molecular Virology, Hellenic Pasteur Institute, 115-21 Athens, Greece; (A.K.); (E.K.); (E.I.K.); (U.G.)
| | - Efthymia Ioanna Koufogeorgou
- Laboratory of Molecular Virology, Hellenic Pasteur Institute, 115-21 Athens, Greece; (A.K.); (E.K.); (E.I.K.); (U.G.)
| | - Stathis D. Kotsakis
- Laboratory of Bacteriology, Hellenic Pasteur Institute, 115-21 Athens, Greece;
| | - Urania Georgopoulou
- Laboratory of Molecular Virology, Hellenic Pasteur Institute, 115-21 Athens, Greece; (A.K.); (E.K.); (E.I.K.); (U.G.)
| | - Pelagia Foka
- Laboratory of Molecular Virology, Hellenic Pasteur Institute, 115-21 Athens, Greece; (A.K.); (E.K.); (E.I.K.); (U.G.)
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Jiang B, Wen X, Wu Q, Bender D, Carra G, Basic M, Kubesch A, Peiffer KH, Boller K, Hildt E. The N-Terminus Makes the Difference: Impact of Genotype-Specific Disparities in the N-Terminal Part of The Hepatitis B Virus Large Surface Protein on Morphogenesis of Viral and Subviral Particles. Cells 2020; 9:cells9081898. [PMID: 32823751 PMCID: PMC7463600 DOI: 10.3390/cells9081898] [Citation(s) in RCA: 4] [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: 06/28/2020] [Revised: 07/27/2020] [Accepted: 08/11/2020] [Indexed: 12/12/2022] Open
Abstract
The N-terminus of the hepatitis B virus (HBV) large surface protein (LHB) differs with respect to genotypes. Compared to the amino terminus of genotype (Gt)D, in GtA, GtB and GtC, an additional identical 11 amino acids (aa) are found, while GtE and GtG share another similar 10 aa. Variants of GtB and GtC affecting this N-terminal part are associated with hepatoma formation. Deletion of these amino-terminal 11 aa in GtA reduces the amount of LHBs and changes subcellular accumulation (GtA-like pattern) to a dispersed distribution (GtD-like pattern). Vice versa, the fusion of the GtA-derived N-terminal 11 aa to GtD causes a GtA-like phenotype. However, insertion of the corresponding GtE-derived 10 aa to GtD has no effect. Deletion of these 11aa decreases filament size while neither the number of released viral genomes nor virion size and infectivity are affected. A negative regulatory element (aa 2–8) and a dominant positive regulatory element (aa 9–11) affecting the amount of LHBs were identified. The fusion of this motif to eGFP revealed that the effect on protein amount and subcellular distribution is not restricted to LHBs. These data identify a novel region in the N-terminus of LHBs affecting the amount and subcellular distribution of LHBs and identify release-promoting and -inhibiting aa residues within this motive.
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Affiliation(s)
- Bingfu Jiang
- Division of Virology, Paul-Ehrlich-Institut, D-63225 Langen, Germany; (B.J.); (X.W.); (Q.W.); (D.B.); (G.C.); (M.B.); (A.K.); (K.-H.P.)
| | - Xingjian Wen
- Division of Virology, Paul-Ehrlich-Institut, D-63225 Langen, Germany; (B.J.); (X.W.); (Q.W.); (D.B.); (G.C.); (M.B.); (A.K.); (K.-H.P.)
| | - Qingyan Wu
- Division of Virology, Paul-Ehrlich-Institut, D-63225 Langen, Germany; (B.J.); (X.W.); (Q.W.); (D.B.); (G.C.); (M.B.); (A.K.); (K.-H.P.)
| | - Daniela Bender
- Division of Virology, Paul-Ehrlich-Institut, D-63225 Langen, Germany; (B.J.); (X.W.); (Q.W.); (D.B.); (G.C.); (M.B.); (A.K.); (K.-H.P.)
| | - Gert Carra
- Division of Virology, Paul-Ehrlich-Institut, D-63225 Langen, Germany; (B.J.); (X.W.); (Q.W.); (D.B.); (G.C.); (M.B.); (A.K.); (K.-H.P.)
| | - Michael Basic
- Division of Virology, Paul-Ehrlich-Institut, D-63225 Langen, Germany; (B.J.); (X.W.); (Q.W.); (D.B.); (G.C.); (M.B.); (A.K.); (K.-H.P.)
- Department of Gastroenterology and Hepatology, J. W. Goethe University, D-60590 Frankfurt, Germany
| | - Alica Kubesch
- Division of Virology, Paul-Ehrlich-Institut, D-63225 Langen, Germany; (B.J.); (X.W.); (Q.W.); (D.B.); (G.C.); (M.B.); (A.K.); (K.-H.P.)
- Department of Gastroenterology and Hepatology, J. W. Goethe University, D-60590 Frankfurt, Germany
| | - Kai-Henrik Peiffer
- Division of Virology, Paul-Ehrlich-Institut, D-63225 Langen, Germany; (B.J.); (X.W.); (Q.W.); (D.B.); (G.C.); (M.B.); (A.K.); (K.-H.P.)
- Department of Gastroenterology and Hepatology, J. W. Goethe University, D-60590 Frankfurt, Germany
| | - Klaus Boller
- Department of Immunology, Paul-Ehrlich-Institut, D-63225 Langen, Germany;
| | - Eberhard Hildt
- Division of Virology, Paul-Ehrlich-Institut, D-63225 Langen, Germany; (B.J.); (X.W.); (Q.W.); (D.B.); (G.C.); (M.B.); (A.K.); (K.-H.P.)
- TTU Hepatitis, German Center for Infection Research (DZIF), 38124 Braunschweig, Germany
- Correspondence: ; Tel.: +496103772140
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5
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Da BL, Heller T, Koh C. Hepatitis D infection: from initial discovery to current investigational therapies. Gastroenterol Rep (Oxf) 2019; 7:231-245. [PMID: 32477569 DOI: 10.1093/gastro/goz023] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/15/2019] [Accepted: 05/09/2019] [Indexed: 02/06/2023] Open
Abstract
Hepatitis D is the most severe form of viral hepatitis associated with a more rapid progression to cirrhosis and an increased risk of hepatocellular carcinoma and mortality compared with hepatitis B mono-infection. Although once thought of as a disappearing disease, hepatitis D is now becoming recognized as a serious worldwide issue due to improvement in diagnostic testing and immigration from endemic countries. Despite these concerns, there is currently only one accepted medical therapy (pegylated-interferon-α) for the treatment of hepatitis D with less than desirable efficacy and significant side effects. Due to these reasons, many patients never undergo treatment. However, increasing knowledge about the virus and its life cycle has led to the clinical development of multiple promising new therapies that hope to alter the natural history of this disease and improve patient outcome. In this article, we will review the literature from discovery to the current investigational therapies.
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Affiliation(s)
- Ben L Da
- Digestive Diseases Branch, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Theo Heller
- Liver Diseases Branch, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Christopher Koh
- Liver Diseases Branch, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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6
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Suwanmanee S, Mahakhunkijcharoen Y, Ampawong S, Leaungwutiwong P, Missé D, Luplertlop N. Inhibition of N-myristoyltransferase1 affects dengue virus replication. Microbiologyopen 2019; 8:e00831. [PMID: 30848105 PMCID: PMC6741125 DOI: 10.1002/mbo3.831] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 02/13/2019] [Accepted: 02/14/2019] [Indexed: 01/05/2023] Open
Abstract
Dengue virus (DENV) causes dengue fever, a self‐limiting disease that could be fatal due to serious complications. No specific treatment is currently available and the preventative vaccine is only partially protective. To develop a potential drug target for dengue fever, we need to understand its biology and pathogenesis thoroughly. N‐myristoyltransferase (NMT) is an N‐terminal protein lipidation enzyme that catalyzes the covalent cotranslational attachment of fatty acids to the amino‐terminal glycine residue of a number of proteins, leading to the modulation of various signaling molecules. In this study, we investigated the interaction of dengue viral proteins with host NMT and its subsequent effect on DENV. Our bioinformatics, molecular docking, and far‐western blotting analyses demonstrated the interaction of viral envelope protein (E) with NMT. The gene expression of NMT was strongly elevated in a dependent manner during the viral replication phase in dendritic cells. Moreover, NMT gene silencing significantly inhibited DENV replication in dendritic cells. Further studies investigating the target cell types of other host factors are suggested.
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Affiliation(s)
- San Suwanmanee
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Yuvadee Mahakhunkijcharoen
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Sumate Ampawong
- Department of Tropical Pathology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Pornsawan Leaungwutiwong
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Dorothée Missé
- MIVEGEC UMR 224, Université de Montpellier, IRD, CNRS, Montpellier, France
| | - Natthanej Luplertlop
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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7
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Qin B, Zhou Y, Zhou G, Xu X, Wang Y, Chen J. Substitutions of rtL228 and/or L229 are involved in the regulation of replication and HBsAg secretion in hepatitis B virus, and do not affect susceptibility to nucleos(t)ide analogs. Mol Med Rep 2017; 16:9678-9684. [PMID: 29039614 DOI: 10.3892/mmr.2017.7778] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 08/22/2017] [Indexed: 11/05/2022] Open
Abstract
Nucleos(t)ide analogs (NAs) are widely used in the treatment of hepatitis B virus (HBV) and human immunodeficiency virus (HIV). The mutation L210W of HIV‑1 reverse transcriptase (RT) is one of the six principal mutations which confer in vivo resistance to zidovudine. Due to the similar 3D‑structure and high conservation between HIV‑RT and HBV‑RT, the present study aimed to clarify whether corresponding mutations in HBV may decrease its susceptibility to relevant NAs. Mutations including rtL228C/W, rtL229W and rtL228W/L229W were introduced into a HBV replication competent plasmid by fusion polymerase chain reaction. Replication capacity, HBs/e antigen (Ag) levels and susceptibility to NAs were subsequently analyzed in vitro. Single or combination mutations of rtL228 and rtL229 impaired HBV replication. Decreased HBsAg secretion in the supernatant and production in the cell lysate wasobserved with single rtL229W or in combination with rtL228W, while there was no significant difference between wild‑type and mutant HBV with regard to the level of HBeAg in the supernatant and susceptibility to commonly‑used NAs. Substitution mutations of rtL228 and/or L229 in HBV did not alter the susceptibility of the virus to NAs, although replication and HBsAg secretion were affected.
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Affiliation(s)
- Bo Qin
- Department of Clinical Laboratory Center, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University, Shaoxing, Zhejiang 312000, P.R. China
| | - Yechao Zhou
- Department of Clinical Laboratory Center, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University, Shaoxing, Zhejiang 312000, P.R. China
| | - Guozhong Zhou
- Department of Clinical Laboratory Center, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University, Shaoxing, Zhejiang 312000, P.R. China
| | - Xiuping Xu
- Department of Clinical Laboratory Center, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University, Shaoxing, Zhejiang 312000, P.R. China
| | - Yanan Wang
- Department of Clinical Laboratory Center, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University, Shaoxing, Zhejiang 312000, P.R. China
| | - Jinkun Chen
- Shaoxing Center for Disease Control and Prevention, Shaoxing, Zhejiang 312000, P.R. China
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Aldabe R, Suárez-Amarán L, Usai C, González-Aseguinolaza G. Animal models of chronic hepatitis delta virus infection host-virus immunologic interactions. Pathogens 2015; 4:46-65. [PMID: 25686091 PMCID: PMC4384072 DOI: 10.3390/pathogens4010046] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 02/05/2015] [Indexed: 02/08/2023] Open
Abstract
Hepatitis delta virus (HDV) is a defective RNA virus that has an absolute requirement for a virus belonging to the hepadnaviridae family like hepatitis B virus (HBV) for its replication and formation of new virions. HDV infection is usually associated with a worsening of HBV-induced liver pathogenesis, which leads to more frequent cirrhosis, increased risk of hepatocellular carcinoma (HCC), and fulminant hepatitis. Importantly, no selective therapies are available for HDV infection. The mainstay of treatment for HDV infection is pegylated interferon alpha; however, response rates to this therapy are poor. A better knowledge of HDV–host cell interaction will help with the identification of novel therapeutic targets, which are urgently needed. Animal models like hepadnavirus-infected chimpanzees or the eastern woodchuck have been of great value for the characterization of HDV chronic infection. Recently, more practical animal models in which to perform a deeper study of host virus interactions and to evaluate new therapeutic strategies have been developed. Therefore, the main focus of this review is to discuss the current knowledge about HDV host interactions obtained from cell culture and animal models.
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Affiliation(s)
- Rafael Aldabe
- Gene Therapy and Regulation of Gene Expression Program, Centro de Investigación Médica Aplicada (CIMA), Universidad de Navarra (UNAV), Pamplona 31008, Spain.
| | - Lester Suárez-Amarán
- Gene Therapy and Regulation of Gene Expression Program, Centro de Investigación Médica Aplicada (CIMA), Universidad de Navarra (UNAV), Pamplona 31008, Spain
| | - Carla Usai
- Gene Therapy and Regulation of Gene Expression Program, Centro de Investigación Médica Aplicada (CIMA), Universidad de Navarra (UNAV), Pamplona 31008, Spain.
| | - Gloria González-Aseguinolaza
- Gene Therapy and Regulation of Gene Expression Program, Centro de Investigación Médica Aplicada (CIMA), Universidad de Navarra (UNAV), Pamplona 31008, Spain.
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9
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Niedre-Otomere B, Bogdanova A, Bruvere R, Ose V, Gerlich WH, Pumpens P, Glebe D, Kozlovska T. Posttranslational modifications and secretion efficiency of immunogenic hepatitis B virus L protein deletion variants. Virol J 2013; 10:63. [PMID: 23442390 PMCID: PMC3598826 DOI: 10.1186/1743-422x-10-63] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 02/20/2013] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Subviral particles of hepatitis B virus (HBV) composed of L protein deletion variants with the 48 N-terminal amino acids of preS joined to the N-terminus of S protein (1-48preS/S) induced broadly neutralizing antibodies after immunization of mice with a Semliki Forest virus vector. A practical limitation for use as vaccine is the suboptimal secretion of such particles. The role of the N-terminal preS myristoylation in the cellular retention of full-length L protein is described controversially in the literature and the relation of these data to the truncated L protein was unknown. Thus, we studied the effect of preS myristoylation signal suppression on 1-48preS/S secretion efficiency, glycosylation and subcellular distribution. FINDINGS The findings are that 1-48preS/S is secreted, and that removal of the N-terminal myristoylation signal in its G2A variant reduced secretion slightly, but significantly. The glycosylation pattern of 1-48preS/S was not affected by the removal of the myristoylation signal (G2A mutant) but was different than natural L protein, whereby N4 of the preS and N3 of the S domain were ectopically glycosylated. This suggested cotranslational translocation of 1-48preS in contrast to natural L protein. The 1-48preS/S bearing a myristoylation signal was localized in a compact, perinuclear pattern with strong colocalization of preS and S epitopes, while the non-myristoylated mutants demonstrated a dispersed, granular cytoplasmic distribution with weaker colocalization. CONCLUSIONS The large deletion in 1-48preS/S in presence of the myristoylation site facilitated formation and secretion of protein particles with neutralizing preS1 epitopes at their surface and could be a useful feature for future hepatitis B vaccines.
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Abstract
Hepatitis delta virus (HDV) is a small, defective RNA virus that can infect only individuals who have hepatitis B virus (HBV); worldwide more than 15 million people are co-infected. There are eight reported genotypes of HDV with unexplained variations in their geographical distribution and pathogenicity. The hepatitis D virion is composed of a coat of HBV envelope proteins surrounding the nucleocapsid, which consists of a single-stranded, circular RNA genome complexed with delta antigen, the viral protein. HDV is clinically important because although it suppresses HBV replication, it causes severe liver disease with rapid progression to cirrhosis and hepatic decompensation. The range of clinical presentation is wide, varying from mild disease to fulminant liver failure. The prevalence of HDV is declining in some endemic areas but increasing in northern and central Europe because of immigration. Treatment of HDV is with pegylated interferon alfa; however, response rates are poor. Increased understanding of the molecular virology of HDV will identify novel therapeutic targets for this most severe form of chronic viral hepatitis.
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Affiliation(s)
- Sarah A Hughes
- Institute of Liver Studies, King's College Hospital, London, UK
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11
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WANG XJ, WANG SQ. Recent Advances in Hepatitis B Virus Entry Research*. PROG BIOCHEM BIOPHYS 2009. [DOI: 10.3724/sp.j.1206.2008.00630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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12
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The pre-S1 and antigenic loop infectivity determinants of the hepatitis B virus envelope proteins are functionally independent. J Virol 2009; 83:12443-51. [PMID: 19759159 DOI: 10.1128/jvi.01594-09] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The hepatitis B virus (HBV) envelope proteins bear two determinants of viral entry: a receptor-binding site (RBS) in the pre-S1 domain of the large envelope protein and a conformation-dependent determinant, of unknown function, in the antigenic loop (AGL) of the small, middle, and large envelope proteins. Using an in vitro infection assay consisting of susceptible HepaRG cells and the hepatitis delta virus (HDV) as a surrogate of HBV, we first investigated whether subelements of the pre-S1 determinant (amino acids 2 to 75), i.e., the N-terminal myristoyl anchor, subdomain 2-48 (RBS), and subdomain 49-75, were functionally separable. In transcomplementation experiments, coexpression of two distinct infectivity-deficient pre-S1 mutants at the surface of HDV virions failed to restore infectivity, indicating that the myristoyl anchor, the 2-48 RBS, and the 49-75 sequence, likely cooperate in cis at viral entry. Furthermore, we showed that as much as 52% of total pre-S1 in the HDV envelope could bear infectivity-deficient lesions without affecting entry, indicating that a small number of pre-S1 polypeptides-estimated at three to four per virion-is sufficient for infectivity. We next investigated the AGL activity in the small or large envelope protein background (S- and L-AGL, respectively) and found that lesions in S-AGL were more deleterious to infectivity than in L-AGL, a difference that reflects the relative stoichiometry of the small and large envelope proteins in the viral envelope. Finally, we showed that C147S, an AGL infectivity-deficient substitution, exerted a dominant-negative effect on infectivity, likely reflecting an involvement of C147 in intermolecular disulfide bonds.
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13
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A function essential to viral entry underlies the hepatitis B virus "a" determinant. J Virol 2009; 83:9321-8. [PMID: 19570861 DOI: 10.1128/jvi.00678-09] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The hepatitis B virus (HBV) particles bear a receptor-binding site located in the pre-S1 domain of the large HBV envelope protein. Using the hepatitis delta virus (HDV) as a surrogate of HBV, a second infectivity determinant was recently identified in the envelope proteins antigenic loop (AGL), and its activity was shown to depend upon cysteine residues that are essential for the structure of the HBV immunodominant "a" determinant. Here, an alanine-scanning mutagenesis approach was used to precisely map the AGL infectivity determinant to a set of conserved residues, which are predicted to cluster together with cysteines in the AGL disulfide bridges network. Several substitutions suppressed both infectivity and the "a" determinant, whereas others were infectivity deficient with only a partial impact on antigenicity. Interestingly, G145R, a substitution often arising under immune pressure selection and detrimental to the "a" determinant, had no effect on infectivity. Altogether, these findings indicate that the AGL infectivity determinant is closely related to, yet separable from, the "a" determinant. Finally, a selection of HDV entry-deficient mutations were introduced at the surface of HBV virions and shown to also abrogate infection in the HBV model. Therefore, a function can at last be assigned to the orphan "a" determinant, the first-discovered marker of HBV infection. The characterization of the AGL functions at viral entry may lead to novel approaches in the development of antivirals against HBV.
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Abstract
Notwithstanding the medical importance of the HBV infection, our understanding of how this pathogen enters hepatocytes is incomplete. This reflects a long-lasting dependence of in vitro infection studies solely on primary human hepatocytes, which are difficult to obtain and maintain in a susceptible state. The establishment of a polarizable HBV-susceptible human hepatoma cell line (HepaRG) and the utilization of Tupaia belangeri hepatocytes (PTHs) resolved this issue. Since then, important insight into viral and cellular determinants participating in HBV binding and infection have been achieved. We now know that the large viral surface protein (L) plays a pivotal role in HBV entry. It mediates diverse functions, commencing binding of virions to heparan sulfate proteoglycans at the hepatocytes surface as a prerequisite for entry. Subsequently, (a) highly specific event(s) involving the myristoylated N-terminal preS1 subdomain of L, as well as the cytosolic and antigenic loops of the S-domain, initiates a series of less well understood steps, resulting in a pH independent, reduction-sensitive fusion of the viral membrane with a cellular membrane. One of these steps is highly sensitive to synthetic N-acylated preS1 lipopeptides and can be blocked in vitro and in vivo at picomolar concentrations. This opens novel therapeutic options addressing virus entry. Future approaches aiming at the elucidation of HBV hepatotropism, the identification of (a) specific receptor(s), the clarification of the endocytic entry pathway and imaging of fluorescently-labeled virions will allow us to decipher more precisely the HBV entry pathway in the near future. Furthermore, clinical efficacy studies with HBV–preS-derived lipopeptides will tell us whether entry inhibition is a passable way to defend acute and chronic HBV and hepatitis delta virus infections.
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Affiliation(s)
- Stephan Urban
- University of Heidelberg, Department of Molecular Virology, Otto-Meyerhof-Zentrum (OMZ), Im Neuenheimer Feld 350, 69120 Heidelberg, Germany
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15
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Abstract
Hepatitis B viruses are small enveloped DNA viruses referred to as Hepadnaviridae that cause transient or persistent (chronic) infections of the liver. This family is divided into two genera, orthohepadnavirus and avihepadnavirus, which infect mammals or birds as natural hosts, respectively. They possess a narrow host range determined by the initial steps of viral attachment and entry. Hepatitis B virus is the focus of biomedical research owing to its medical significance. Approximately 2 billion people have serological evidence of hepatitis B, and of these approximately 350 million people have chronic infections (World Health Organisation, Fact Sheet WHO/204, October 2000). Depending on viral and host factors, the outcomes of infection with hepatitis B virus vary between acute hepatitis, mild or severe chronic hepatitis or cirrhosis. Chronic infections are associated with an increased risk for the development of hepatocellular carcinoma.
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Affiliation(s)
- Hans-Jürgen Netter
- Monash University, Department of Microbiology, Clayton Campus, Victoria 3800, Australia
| | - Shau-Feng Chang
- Industrial Technology Research Institute, Biomedical Engineering Laboratories, 300 Hsinchu, Taiwan
| | - Michael Bruns
- Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie an der Universität Hamburg, 20251 Hamburg, Germany
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16
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Serum-derived hepatitis C virus infection of primary human hepatocytes is tetraspanin CD81 dependent. J Virol 2007; 82:569-74. [PMID: 17942559 DOI: 10.1128/jvi.01443-07] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hepatitis C virus-positive serum (HCVser, genotypes 1a to 3a) or HCV cell culture (JFH1/HCVcc) infection of primary normal human hepatocytes was assessed by measuring intracellular HCV RNA strands. Anti-CD81 antibodies and siRNA-CD81 silencing markedly inhibited (>90%) HCVser infection irrespective of HCV genotype, viral load, or liver donor, while hCD81-large intracellular loop (LEL) had no effect. However, JFH1/HCVcc infection of hepatocytes was modestly inhibited (40 to 60%) by both hCD81-LEL and anti-CD81 antibodies. In conclusion, CD81 is involved in HCVser infection of human hepatocytes, and comparative studies of HCVser versus JFH1/HCVcc infection of human hepatocytes and Huh-7.5 cells revealed that the cell-virion combination is determinant of the entry process.
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