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Phinius BB, Choga WT, Anderson M, Mokomane M, Gobe I, Ratsoma T, Phakedi B, Mpebe G, Bhebhe L, Gaolathe T, Mosepele M, Makhema J, Shapiro R, Lockman S, Musonda R, Moyo S, Gaseitsiwe S. Molecular Characterization of Hepatitis B Virus in People Living with HIV in Rural and Peri-Urban Communities in Botswana. Biomedicines 2024; 12:1561. [PMID: 39062134 PMCID: PMC11275055 DOI: 10.3390/biomedicines12071561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2024] [Revised: 07/10/2024] [Accepted: 07/12/2024] [Indexed: 07/28/2024] Open
Abstract
(1) Background: Hepatitis B virus (HBV) sequencing data are important for monitoring HBV evolution. We aimed to molecularly characterize HBV sequences from participants with HBV surface antigen-positive (HBsAg+) serology and occult hepatitis B infection (OBI+). (2) Methods: We utilized archived plasma samples from people living with human immunodeficiency virus (PLWH) in Botswana. HBV DNA was sequenced, genotyped and analyzed for mutations. We compared mutations from study sequences to those from previously generated HBV sequences in Botswana. The impact of OBI-associated mutations on protein function was assessed using the Protein Variation Effect Analyzer. (3) Results: Sequencing success was higher in HBsAg+ than in OBI+ samples [86/128 (67.2%) vs. 21/71 (29.2%)]. Overall, 93.5% (100/107) of sequences were genotype A1, 2.8% (3/107) were D3 and 3.7% (4/107) were E. We identified 13 escape mutations in 18/90 (20%) sequences with HBsAg coverage, with K122R having the highest frequency. The mutational profile of current sequences differed from previous Botswana HBV sequences, suggesting possible mutational changes over time. Mutations deemed to have an impact on protein function were tpQ6H, surfaceV194A and preCW28L. (4) Conclusions: We characterized HBV sequences from PLWH in Botswana. Escape mutations were prevalent and were not associated with OBI. Longitudinal HBV studies are needed to investigate HBV natural evolution.
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Affiliation(s)
- Bonolo B. Phinius
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
- School of Allied Health Professions, Faculty of Health Sciences, University of Botswana, Gaborone Private Bag UB0022, Botswana; (M.M.); (I.G.)
| | - Wonderful T. Choga
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
- School of Allied Health Professions, Faculty of Health Sciences, University of Botswana, Gaborone Private Bag UB0022, Botswana; (M.M.); (I.G.)
| | - Motswedi Anderson
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
- Africa Health Research Institute (AHRI), Private Bag X7, Congella, Durban 4013, South Africa
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Margaret Mokomane
- School of Allied Health Professions, Faculty of Health Sciences, University of Botswana, Gaborone Private Bag UB0022, Botswana; (M.M.); (I.G.)
| | - Irene Gobe
- School of Allied Health Professions, Faculty of Health Sciences, University of Botswana, Gaborone Private Bag UB0022, Botswana; (M.M.); (I.G.)
| | - Tsholofelo Ratsoma
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
| | - Basetsana Phakedi
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
| | - Gorata Mpebe
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
| | - Lynnette Bhebhe
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
| | - Tendani Gaolathe
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
- Faculty of Medicine, University of Botswana, Gaborone Private Bag UB0022, Botswana
| | - Mosepele Mosepele
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
- Faculty of Medicine, University of Botswana, Gaborone Private Bag UB0022, Botswana
| | - Joseph Makhema
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA
| | - Roger Shapiro
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA
| | - Shahin Lockman
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA
| | - Rosemary Musonda
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA
| | - Sikhulile Moyo
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
- School of Allied Health Professions, Faculty of Health Sciences, University of Botswana, Gaborone Private Bag UB0022, Botswana; (M.M.); (I.G.)
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA
- Division of Medical Virology, Faculty of Medicine and Health Sciences, Stellenbosch University, Private Bag X1, Matieland, Cape Town 7602, South Africa
- School of Health Systems and Public Health, University of Pretoria, Private Bag X20, Pretoria 0028, South Africa
| | - Simani Gaseitsiwe
- Botswana Harvard Health Partnership, Gaborone Private Bag BO320, Botswana; (B.B.P.); (S.M.)
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA
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Jia Y, Zhao J, Wang C, Meng J, Zhao L, Yang H, Zhao X. HBV DNA polymerase upregulates the transcription of PD-L1 and suppresses T cell activity in hepatocellular carcinoma. J Transl Med 2024; 22:272. [PMID: 38475878 PMCID: PMC10936085 DOI: 10.1186/s12967-024-05069-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 03/06/2024] [Indexed: 03/14/2024] Open
Abstract
BACKGROUND In HBV-associated HCC, T cells often exhibit a state of functional exhaustion, which prevents the immune response from rejecting the tumor and allows HCC to progress. Moreover, polymerase-specific T cells exhibit more severe T-cell exhaustion compared to core-specific T cells. However, whether HBV DNA polymerase drives HBV-specific CD8+ T cell exhaustion in HBV-related HCC remains unclear. METHODS We constructed a Huh7 cell line stably expressing HA-HBV-DNA-Pol and applied co-culture systems to clarify its effect on immune cell function. We also examined how HBV-DNA-Pol modulated PD-L1 expression in HCC cells. In addition, HBV-DNA-Pol transgenic mice were used to elucidate the underlying mechanism of HBV-DNA-Pol/PD-L1 axis-induced T cell exhaustion. RESULTS Biochemical analysis showed that Huh7 cells overexpressing HBV-DNA-Pol inhibited the proliferation, activation, and cytokine secretion of Jurkat cells and that this effect was dependent on their direct contact. A similar inhibitory effect was observed in an HCC mouse model. PD-L1 was brought to our attention during screening. Our results showed that the overexpression of HBV-DNA-Pol upregulated PD-L1 mRNA and protein expression. PD-L1 antibody blockade reversed the inhibitory effect of Huh7 cells overexpressing HBV-DNA-Pol on Jurkat cells. Mechanistically, HBV-DNA-Pol interacts with PARP1, thereby inhibiting the nuclear translocation of PARP1 and further upregulating PD-L1 expression. CONCLUSIONS Our findings suggest that HBV-DNA-Pol can act as a regulator of PD-L1 in HCC, thereby directing anti-cancer immune evasion, which further provides a new idea for the clinical treatment of liver cancer.
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Affiliation(s)
- Yan Jia
- Department of Laboratory Medicine, Tianjin Hospital, Tianjin, 300211, China
| | - Jianing Zhao
- Department of Pathology, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, 050011, China
| | - Chunqing Wang
- Department of Clinical Laboratory Medicine, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Medicine and Health Key Laboratory of Laboratory Medicine, Jinan, 250014, China
| | - Jing Meng
- Department of Clinical Laboratory, The Second Hospital, Cheeloo College of Medicine, Shandong University, Jinan, 250033, China
| | - Liqing Zhao
- Department of Pediatrics, Zaozhuang Municipal Hospital, Zaozhuang, 277100, China
| | - Hongwei Yang
- Department of Laboratory Medicine, Tianjin Hospital, Tianjin, 300211, China
| | - Xiaoqing Zhao
- Department of Clinical Laboratory, The Second Hospital, Cheeloo College of Medicine, Shandong University, Jinan, 250033, China.
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3
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Ranga A, Gupta A, Yadav L, Kumar S, Jain P. Advancing beyond reverse transcriptase inhibitors: The new era of hepatitis B polymerase inhibitors. Eur J Med Chem 2023; 257:115455. [PMID: 37216809 DOI: 10.1016/j.ejmech.2023.115455] [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: 02/28/2023] [Revised: 05/03/2023] [Accepted: 05/03/2023] [Indexed: 05/24/2023]
Abstract
Hepatitis B virus (HBV) is a genetically diverse blood-borne virus responsible for chronic hepatitis B. The HBV polymerase plays a key role in viral genome replication within the human body and has been identified as a potential drug target for chronic hepatitis B therapeutics. However, available nucleotide reverse transcriptase inhibitors only target the reverse transcriptase domain of the HBV polymerase; they also pose resistance issues and require lifelong treatment that can burden patients financially. In this study, various chemical classes are reviewed that have been developed to target different domains of the HBV polymerase: Terminal protein, which plays a vital role in the formation of the viral DNA; Reverse transcriptase, which is responsible for the synthesis of the viral DNA from RNA, and; Ribonuclease H, which is responsible for degrading the RNA strand in the RNA-DNA duplex formed during the reverse transcription process. Host factors that interact with the HBV polymerase to achieve HBV replication are also reviewed; these host factors can be targeted by inhibitors to indirectly inhibit polymerase functionality. A detailed analysis of the scope and limitations of these inhibitors from a medicinal chemistry perspective is provided. The structure-activity relationship of these inhibitors and the factors that may affect their potency and selectivity are also examined. This analysis will be useful in supporting the further development of these inhibitors and in designing new inhibitors that can inhibit HBV replication more efficiently.
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Affiliation(s)
- Abhishek Ranga
- Department of Pharmacology, Delhi Institute of Pharmaceutical Sciences and Research, Delhi Pharmaceutical Sciences and Research University, Pushp Vihar, MB Road, New Delhi, 110017, India
| | - Aarti Gupta
- Department of Pharmaceutical Biotechnology, Delhi Pharmaceutical Sciences and Research University, Pushp Vihar, MB Road, New Delhi, 110017, India
| | - Laxmi Yadav
- Department of Pharmacology, Delhi Institute of Pharmaceutical Sciences and Research, Delhi Pharmaceutical Sciences and Research University, Pushp Vihar, MB Road, New Delhi, 110017, India
| | - Sachin Kumar
- Department of Pharmacology, Delhi Institute of Pharmaceutical Sciences and Research, Delhi Pharmaceutical Sciences and Research University, Pushp Vihar, MB Road, New Delhi, 110017, India.
| | - Priti Jain
- Department of Pharmaceutical Chemistry, Delhi Pharmaceutical Sciences and Research University, Pushp Vihar, MB Road, New Delhi, 110017, India.
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4
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Tajwar R, Bradley DP, Ponzar NL, Tavis JE. Predicted structure of the hepatitis B virus polymerase reveals an ancient conserved protein fold. Protein Sci 2022; 31:e4421. [PMID: 36173165 PMCID: PMC9601786 DOI: 10.1002/pro.4421] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 07/31/2022] [Accepted: 08/02/2022] [Indexed: 11/12/2022]
Abstract
Hepatitis B virus (HBV) chronically infects >250 million people. It replicates by a unique protein-primed reverse transcription mechanism, and the primary anti-HBV drugs are nucleos(t)ide analogs targeting the viral polymerase (P). P has four domains compared to only two in most reverse transcriptases: the terminal protein (TP) that primes DNA synthesis, a spacer, the reverse transcriptase (RT), and the ribonuclease H (RNase H). Despite being a major drug target and catalyzing a reverse transcription pathway very different from the retroviruses, HBV P has resisted structural analysis for decades. Here, we exploited computational advances to model P. The TP wrapped around the RT domain rather than forming the anticipated globular domain, with the priming tyrosine poised over the RT active site. The orientation of the RT and RNase H domains resembled that of the retroviral enzymes despite the lack of sequences analogous to the retroviral linker region. The model was validated by mapping residues with known surface exposures, docking nucleic acids, mechanistically interpreting mutations with strong phenotypes, and docking inhibitors into the RT and RNase H active sites. The HBV P fold, including the orientation of the TP domain, was conserved among hepadnaviruses infecting rodent to fish hosts and a nackednavirus, but not in other non-retroviral RTs. Therefore, this protein fold has persisted since the hepadnaviruses diverged from nackednaviruses >400 million years ago. This model will advance mechanistic analyses into the poorly understood enzymology of HBV reverse transcription and will enable drug development against non-active site targets for the first time.
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Affiliation(s)
- Razia Tajwar
- Department of Molecular Microbiology and Immunology, School of Medicine and Institute for Drug and Biotherapeutic InnovationSaint Louis UniversitySaint LouisMissouriUSA
| | - Daniel P. Bradley
- Department of Molecular Microbiology and Immunology, School of Medicine and Institute for Drug and Biotherapeutic InnovationSaint Louis UniversitySaint LouisMissouriUSA
| | - Nathan L. Ponzar
- Department of Molecular Microbiology and Immunology, School of Medicine and Institute for Drug and Biotherapeutic InnovationSaint Louis UniversitySaint LouisMissouriUSA
| | - John E. Tavis
- Department of Molecular Microbiology and Immunology, School of Medicine and Institute for Drug and Biotherapeutic InnovationSaint Louis UniversitySaint LouisMissouriUSA
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5
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Abstract
Hepatitis B virus (HBV) is a hepatotropic, partially double-stranded DNA virus that replicates by reverse transcription and is a major cause of chronic liver disease and hepatocellular carcinoma. Reverse transcription is catalyzed by the four-domain multifunctional HBV polymerase (P) protein that has protein-priming, RNA- and DNA-dependent DNA synthesis (i.e., reverse transcriptase), and ribonuclease H activities. P also likely promotes the three strand transfers that occur during reverse transcription, and it may participate in immune evasion by HBV. Reverse transcription is primed by a tyrosine residue in the amino-terminal domain of P, and P remains covalently attached to the product DNA throughout reverse transcription. The reverse transcriptase activity of P is the target for the nucleos(t)ide analog drugs that dominate HBV treatment, and P is the target of ongoing efforts to develop new drugs against both the reverse transcriptase and ribonuclease H activities. Despite the unusual reverse transcription pathway catalyzed by P and the importance of P to HBV therapy, understanding the enzymology and structure of HBV P severely lags that of the retroviral reverse transcriptases due to substantial technical challenges to studying the enzyme. Obtaining a better understanding of P will broaden our appreciation of the diversity among reverse transcribing elements in nature, and will help improve treatment for people chronically infected with HBV.
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Affiliation(s)
- Daniel N Clark
- Department of Microbiology, Weber State University, Ogden, UT, United States
| | - Razia Tajwar
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, MO, United States
| | - Jianming Hu
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, PA, United States
| | - John E Tavis
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, MO, United States.
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6
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rt269I Type of Hepatitis B Virus (HBV) Polymerase versus rt269L Is More Prone to Mutations within HBV Genome in Chronic Patients Infected with Genotype C2: Evidence from Analysis of Full HBV Genotype C2 Genome. Microorganisms 2021; 9:microorganisms9030601. [PMID: 33803998 PMCID: PMC7999911 DOI: 10.3390/microorganisms9030601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/08/2021] [Accepted: 03/10/2021] [Indexed: 12/03/2022] Open
Abstract
Recently, it has been reported that the rt269I type of hepatitis B virus (HBV) polymerase (Pol) versus the rt269L type is more significantly related to lower viral replication and HBeAg negative infections in chronic hepatitis B (CHB) patients of genotype C2. In this study, we compared mutation rates within HBV genomes between rt269L and rt269I using a total of 234 HBV genotype C2 full genome sequences randomly selected from the HBV database (115 of rt269L and 119 of rt269I type). When we applied the Benjamini and Hochberg procedure for multiple comparisons, two parameters, dN and d, at the amino acids level in the Pol region were significantly higher in the rt269I type than in the rt269L type. Although it could not reach statistical significance from the Benjamini and Hochberg procedure, nonsynonymous (NS) mutations in the major hydrophilic region (MHR) or “a” determinant in the surface antigens (HBsAg ORF) related to host immune escape or vaccine escape are more frequently generated in rt269I strains than in rt269L. We also found that there are a total of 19 signature single nucleotide polymorphisms (SNPs), of which 2 and 17 nonsynonymous mutation types were specific to rt269L and rt269I, respectively: Of these, most are HBeAg negative infections (preC-W28*, X-V5M and V131I), lowered HBV DNA or virion production (C-I97F/L, rtM204I/V) or preexisting nucleot(s)ide analog resistance (NAr) (rtN139K/H, rtM204I/V and rtI224V) or disease severity (preC-W28*, C-I97F/L, C-Q182K/*, preS2-F141L, S-L213I/S, V/L5M, T36P/S/A, V131I, rtN139K/H, rtM204I/V and rtI224V). In conclusion, our data showed that rt269I types versus rt269L types are more prone to overall genome mutations, particularly in the Pol region and in the MHR or “a” determinant in genotype C2 infections and are more prevalent in signature NS mutations related to lowered HBV DNA replication, HBsAg and HBeAg secretion and potential NAr variants and hepatocellular carcinoma (HCC), possibly via type I interferon (IFN-I)-mediated enhanced inflammation. Our data suggest that rt269L types could contribute to liver disease progression via the generation of immune escape or enhanced persistent infection in chronic patients of genotype C2.
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Hu Z, Ban H, Zheng H, Liu M, Chang J, Guo JT. Protein phosphatase 1 catalyzes HBV core protein dephosphorylation and is co-packaged with viral pregenomic RNA into nucleocapsids. PLoS Pathog 2020; 16:e1008669. [PMID: 32702076 PMCID: PMC7402523 DOI: 10.1371/journal.ppat.1008669] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 08/04/2020] [Accepted: 05/30/2020] [Indexed: 01/01/2023] Open
Abstract
Hepatitis B virus (HBV) replicates its genomic DNA via viral DNA polymerase self-primed reverse transcription of a RNA pre-genome in the nucleocapsid assembled by 120 core protein (Cp) dimers. The arginine-rich carboxyl-terminal domain (CTD) of Cp plays an important role in the selective packaging of viral DNA polymerase-pregenomic (pg) RNA complex into nucleocapsid. Previous studies suggested that the CTD is initially phosphorylated at multiple sites to facilitate viral RNA packaging and subsequently dephosphorylated in association with viral DNA synthesis and secretion of DNA-containing virions. However, our recent studies suggested that Cp is hyper-phosphorylated as free dimers and its dephosphorylation is associated with pgRNA encapsidation. Herein, we provide further genetic and biochemical evidence supporting that extensive Cp dephosphorylation does take place during the assembly of pgRNA-containing nucleocapsids, but not empty capsids. Moreover, we found that cellular protein phosphatase 1 (PP1) is required for Cp dephosphorylation and pgRNA packaging. Interestingly, the PP1 catalytic subunits α and β were packaged into pgRNA-containing nucleocapsids, but not empty capsids, and treatment of HBV replicating cells with core protein allosteric modulators (CpAMs) promoted empty capsid assembly and abrogated the encapsidation of PP1 α and β. Our study thus identified PP1 as a host cellular factor that is co-packaged into HBV nucleocapsids, and plays an essential role in selective packaging of the viral DNA-polymerase-pgRNA complex through catalyzing Cp dephosphorylation. Selective packaging of pregenomic RNA by core protein dimers into nucleocapsid is a key step of HBV replication and is subjected for the regulation by multiple viral and host cellular factors. HBV core protein phosphorylation and dephosphorylation play an essential role in HBV genome replication. However, the cellular kinases and phosphatases responsible for the biochemical events remain elusive. Identification of cellular protein phosphatase 1 as a host cellular factor catalyzing core protein dephosphorylation and facilitating viral pregenomic RNA packaging into nucleocapsids sheds new light on the molecular mechanism of HBV replication and development of therapeutics to cure chronic HBV infection.
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Affiliation(s)
- Zhanying Hu
- Department of Experimental Therapeutics, Baruch S. Blumberg Institute, Doylestown, Pennsylvania, United States of America
| | - Haiqun Ban
- Department of Experimental Therapeutics, Baruch S. Blumberg Institute, Doylestown, Pennsylvania, United States of America
| | - Haiyan Zheng
- Biological mass spectrometry facility, Robert Wood Johnson Medical School and Rutgers, The State University of New Jersey. Piscataway, New Jersey, United States of America
| | - Mingliang Liu
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Tian-Tan Xi-Li, Beijing, China
| | - Jinhong Chang
- Department of Experimental Therapeutics, Baruch S. Blumberg Institute, Doylestown, Pennsylvania, United States of America
| | - Ju-Tao Guo
- Department of Experimental Therapeutics, Baruch S. Blumberg Institute, Doylestown, Pennsylvania, United States of America
- * E-mail:
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Molecular, Evolutionary, and Structural Analysis of the Terminal Protein Domain of Hepatitis B Virus Polymerase, a Potential Drug Target. Viruses 2020; 12:v12050570. [PMID: 32455999 PMCID: PMC7291194 DOI: 10.3390/v12050570] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/17/2020] [Accepted: 05/19/2020] [Indexed: 12/15/2022] Open
Abstract
Approximately 250 million people are living with chronic hepatitis B virus (HBV) infections, which claim nearly a million lives annually. The target of all current HBV drug therapies (except interferon) is the viral polymerase; specifically, the reverse transcriptase domain. Although no high-resolution structure exists for the HBV polymerase, several recent advances have helped to map its functions to specific domains. The terminal protein (TP) domain, unique to hepadnaviruses such as HBV, has been implicated in the binding and packaging of the viral RNA, as well as the initial priming of and downstream synthesis of viral DNA—all of which make the TP domain an attractive novel drug target. This review encompasses three types of analysis: sequence conservation analysis, secondary structure prediction, and the results from mutational studies. It is concluded that the TP domain of HBV polymerase is comprised of seven subdomains (three unstructured loops and four helical regions) and that all three loop subdomains and Helix 5 are the major determinants of HBV function within the TP domain. Further studies, such as modeling inhibitors of these critical TP subdomains, will advance the TP domain of HBV polymerase as a therapeutic drug target in the progression towards a cure.
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9
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Mu T, Zhao X, Zhu Y, Fan H, Tang H. The E3 Ubiquitin Ligase TRIM21 Promotes HBV DNA Polymerase Degradation. Viruses 2020; 12:v12030346. [PMID: 32245233 PMCID: PMC7150939 DOI: 10.3390/v12030346] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 03/18/2020] [Accepted: 03/19/2020] [Indexed: 12/26/2022] Open
Abstract
The tripartite motif (TRIM) protein family is an E3 ubiquitin ligase family. Recent reports have indicated that some TRIM proteins have antiviral functions, especially against retroviruses. However, most studies mainly focus on the relationship between TRIM21 and interferon or other antiviral effectors. The effect of TRIM21 on virus-encoded proteins remains unclear. In this study, we screened candidate interacting proteins of HBV DNA polymerase (Pol) by FLAG affinity purification and mass spectrometry assay and identified TRIM21 as its regulator. We used a coimmunoprecipitation (co-IP) assay to demonstrate that TRIM21 interacted with the TP domain of HBV DNA Pol. In addition, TRIM21 promoted the ubiquitination and degradation of HBV DNA Pol using its RING domain, which has E3 ubiquitin ligase activity. Lys260 and Lys283 of HBV DNA Pol were identified as targets for ubiquitination mediated by TRIM21. Finally, we uncovered that TRIM21 degrades HBV DNA Pol to restrict HBV DNA replication, and its SPRY domain is critical for this activity. Taken together, our results indicate that TRIM21 suppresses HBV DNA replication mainly by promoting the ubiquitination of HBV DNA Pol, which may provide a new potential target for the treatment of HBV.
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Affiliation(s)
| | | | | | | | - Hua Tang
- Correspondence: ; Tel./Fax: +86-22-2354-2503
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10
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Discovery and Selection of Hepatitis B Virus-Derived T Cell Epitopes for Global Immunotherapy Based on Viral Indispensability, Conservation, and HLA-Binding Strength. J Virol 2020; 94:JVI.01663-19. [PMID: 31852786 PMCID: PMC7081907 DOI: 10.1128/jvi.01663-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 12/10/2019] [Indexed: 12/15/2022] Open
Abstract
Multiple HBV-derived T cell epitopes have been reported, which can be useful in a therapeutic vaccination strategy. However, these epitopes are largely restricted to HLA-A*02, which is not dominantly expressed in populations with high HBV prevalence. Thus, current epitopes are falling short in the development of a global immunotherapeutic approach. Therefore, we aimed to identify novel epitopes for 6 HLA supertypes most prevalent in the infected population. Moreover, established epitopes might not all be equally effective as they can be subject to different levels of immune escape. It is therefore important to identify targets that are crucial in viral replication and conserved in the majority of the infected population. Here, we applied a stringent selection procedure to compose a combined overview of existing and novel HBV-derived T cell epitopes most promising for viral eradication. This set of T cell epitopes now lays the basis for the development of globally effective HBV antigen-specific immunotherapies. Immunotherapy represents an attractive option for the treatment of chronic hepatitis B virus (HBV) infection. The HBV proteins polymerase (Pol) and HBx are of special interest for antigen-specific immunotherapy because they are essential for viral replication and have been associated with viral control (Pol) or are still expressed upon viral DNA integration (HBx). Here, we scored all currently described HBx- and Pol-derived epitope sequences for viral indispensability and conservation across all HBV genotypes. This yielded 7 HBx-derived and 26 Pol-derived reported epitopes with functional association and high conservation. We subsequently predicted novel HLA-binding peptides for 6 HLA supertypes prevalent in HBV-infected patients. Potential epitopes expected to be the least prone to immune escape were subjected to a state-of-the-art in vitro assay to validate their HLA-binding capacity. Using this method, a total of 13 HLA binders derived from HBx and 33 binders from Pol were identified across HLA types. Subsequently, we demonstrated interferon gamma (IFN-γ) production in response to 5 of the novel HBx-derived binders and 17 of the novel Pol-derived binders. In addition, we validated several infrequently described epitopes. Collectively, these results specify a set of highly potent T cell epitopes that represent a valuable resource for future HBV immunotherapy design. IMPORTANCE Multiple HBV-derived T cell epitopes have been reported, which can be useful in a therapeutic vaccination strategy. However, these epitopes are largely restricted to HLA-A*02, which is not dominantly expressed in populations with high HBV prevalence. Thus, current epitopes are falling short in the development of a global immunotherapeutic approach. Therefore, we aimed to identify novel epitopes for 6 HLA supertypes most prevalent in the infected population. Moreover, established epitopes might not all be equally effective as they can be subject to different levels of immune escape. It is therefore important to identify targets that are crucial in viral replication and conserved in the majority of the infected population. Here, we applied a stringent selection procedure to compose a combined overview of existing and novel HBV-derived T cell epitopes most promising for viral eradication. This set of T cell epitopes now lays the basis for the development of globally effective HBV antigen-specific immunotherapies.
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Oropeza CE, Tarnow G, Sridhar A, Taha TY, Shalaby RE, McLachlan A. The Regulation of HBV Transcription and Replication. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1179:39-69. [PMID: 31741333 DOI: 10.1007/978-981-13-9151-4_3] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Hepatitis B virus (HBV) is a major human pathogen lacking a reliable curative therapy. Current therapeutics target the viral reverse transcriptase/DNA polymerase to inhibit viral replication but generally fail to resolve chronic HBV infections. Due to the limited coding potential of the HBV genome, alternative approaches for the treatment of chronic infections are desperately needed. An alternative approach to the development of antiviral therapeutics is to target cellular gene products that are critical to the viral life cycle. As transcription of the viral genome is an essential step in the viral life cycle, the selective inhibition of viral RNA synthesis is a possible approach for the development of additional therapeutic modalities that might be used in combination with currently available therapies. To address this possibility, a molecular understanding of the relationship between viral transcription and replication is required. The first step is to identify the transcription factors that are the most critical in controlling the levels of HBV RNA synthesis and to determine their in vivo role in viral biosynthesis. Mapping studies in cell culture utilizing reporter gene constructs permitted the identification of both ubiquitous and liver-enriched transcription factors capable of modulating transcription from the four HBV promoters. However, it was challenging to determine their relative importance for viral biosynthesis in the available human hepatoma replication systems. This technical limitation was addressed, in part, by the development of non-hepatoma HBV replication systems where viral biosynthesis was dependent on complementation with exogenously expressed transcription factors. These systems revealed the importance of specific nuclear receptors and hepatocyte nuclear factor 3 (HNF3)/forkhead box A (FoxA) transcription factors for HBV biosynthesis. Furthermore, using the HBV transgenic mouse model of chronic viral infection, the importance of various nuclear receptors and FoxA isoforms could be established in vivo. The availability of this combination of systems now permits a rational approach toward the development of selective host transcription factor inhibitors. This might permit the development of a new class of therapeutics to aid in the treatment and resolution of chronic HBV infections, which currently affects approximately 1 in 30 individuals worldwide and kills up to a million people annually.
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Affiliation(s)
- Claudia E Oropeza
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Grant Tarnow
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Abhayavarshini Sridhar
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Taha Y Taha
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Rasha E Shalaby
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.,Department of Microbiology and Immunology, Faculty of Medicine, Tanta University, Egypt, Egypt
| | - Alan McLachlan
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
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Liu K, Luckenbaugh L, Ning X, Xi J, Hu J. Multiple roles of core protein linker in hepatitis B virus replication. PLoS Pathog 2018; 14:e1007085. [PMID: 29782550 PMCID: PMC5983865 DOI: 10.1371/journal.ppat.1007085] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 06/01/2018] [Accepted: 05/09/2018] [Indexed: 12/16/2022] Open
Abstract
Hepatitis B virus (HBV) core protein (HBc) contains an N-terminal domain (NTD, assembly domain) and a C-terminal domain (CTD), which are linked by a flexible linker region. HBc plays multiple essential roles in viral replication, including capsid assembly, packaging of the viral pregenomic RNA (pgRNA) into nucleocapsids, viral reverse transcription that converts pgRNA to the genomic DNA, and secretion of DNA-containing (complete) virions or genome-free (empty) virions. The HBc linker is generally assumed to act merely as a spacer between NTD and CTD but some results suggest that the linker may affect NTD assembly. To determine its role in viral replication, we have made a number of deletion and substitution mutants in the linker region, in either the presence or absence of CTD, and tested their abilities to support capsid assembly and viral replication in human cells. Our results indicate that the linker could indeed impede NTD assembly in the absence of CTD, which could be partially relieved by partial linker deletion. In contrast, when CTD was present, the linker deletions or substitutions did not affect capsid assembly. Deletion of the entire linker or its C-terminal part resulted in a partial defect in pgRNA packaging and severely impaired viral DNA synthesis. In contrast, deletion of the N-terminal part of the linker, or substitutions of the linker sequence, had little to no effect on RNA packaging or first-strand DNA synthesis. However, the N-terminal linker deletion and two linker substitution mutants were defective in the production of mature double-stranded viral DNA. Secretion of empty virions was blocked by all the linker deletions and substitutions tested. In particular, a conservative linker substitution that allowed mature viral DNA synthesis and secretion of complete virions severely impaired the secretion of empty virions, thus increasing the ratio of complete to empty virions that were secreted. Together, these results demonstrate that the HBc linker region plays critical and complex roles at multiple stages of HBV replication. The hepatitis B virus (HBV) is a major human pathogen that infects hundreds of millions of people worldwide and represents a major cause of viral hepatitis, liver cirrhosis, and liver cancer. The HBV capsid protein (HBc) plays multiple roles in the viral life cycle and has emerged recently as a major target for developing antiviral therapies against HBV infection. HBc is divided into three separate regions, an N-terminal domain (NTD) responsible for capsid assembly, a C-terminal domain (CTD) that plays critical roles in the specific packaging of the viral pregenomic RNA (pgRNA) into replication-competent nucleocapsids and the subsequent reverse transcription of the pgRNA into the viral genomic DNA, and a linker region between the NTD and CTD. In contrast to the prevailing assumption that the linker merely serves to connect the NTD and CTD, we have discovered here that it plays a critical role in almost every stage of HBV replication. The linker likely exerted its pleiotropic effects via affecting the NTD and CTD as well as via direct interactions with other viral factors independent of the NTD or CTD. Our results thus not only deepen understanding of HBc structure and functions but also implicate the linker as a potential novel target for antiviral development against HBV infection.
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Affiliation(s)
- Kuancheng Liu
- Department of Microbiology and Immunology, Penn State University College of Medicine, Hershey, PA, United States of America
- College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou, China
| | - Laurie Luckenbaugh
- Department of Microbiology and Immunology, Penn State University College of Medicine, Hershey, PA, United States of America
| | - Xiaojun Ning
- Department of Microbiology and Immunology, Penn State University College of Medicine, Hershey, PA, United States of America
| | - Ji Xi
- Department of Microbiology and Immunology, Penn State University College of Medicine, Hershey, PA, United States of America
| | - Jianming Hu
- Department of Microbiology and Immunology, Penn State University College of Medicine, Hershey, PA, United States of America
- * E-mail:
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Novel Genetic Variants of Hepatitis B Virus in Fulminant Hepatitis. J Pathog 2017; 2017:1231204. [PMID: 29410920 PMCID: PMC5749291 DOI: 10.1155/2017/1231204] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 11/20/2017] [Indexed: 02/06/2023] Open
Abstract
Fulminant hepatitis (FH) is a life-threatening liver disease characterised by intense immune attack and massive liver cell death. The common precore stop codon mutation of hepatitis B virus (HBV), A1896, is frequently associated with FH, but lacks specificity. This study attempts to uncover all possible viral nucleotides that are specifically associated with FH through a compiled sequence analysis of FH and non-FH cases from acute infection. We retrieved 67 FH and 280 acute non-FH cases of hepatitis B from GenBank and applied support vector machine (SVM) model to seek candidate nucleotides highly predictive of FH. Six best candidates with top predictive accuracy, 92.5%, were used to build a SVM model; they are C2129 (85.3%), T720 (83.0%), Y2131 (82.4%), T2013 (82.1%), K2048 (82.1%), and A2512 (82.1%). This model gave a high specificity (99.3%), positive predictive value (95.6%), and negative predictive value (92.1%), but only moderate sensitivity (64.2%). We successfully built a SVM model comprising six variants that are highly predictive and specific for FH: four in the core region and one each in the polymerase and the surface regions. These variants indicate that intracellular virion/core retention could play an important role in the progression to FH.
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