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McCoullough LC, Fareh M, Hu W, Sozzi V, Makhlouf C, Droungas Y, Lee CL, Takawy M, Fabb SA, Payne TJ, Pouton CW, Netter HJ, Lewin SR, Purcell DF, Holmes JA, Trapani JA, Littlejohn M, Revill PA. CRISPR-Cas13b-mediated suppression of HBV replication and protein expression. J Hepatol 2024; 81:794-805. [PMID: 38815932 DOI: 10.1016/j.jhep.2024.05.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 04/19/2024] [Accepted: 05/16/2024] [Indexed: 06/01/2024]
Abstract
BACKGROUND & AIMS New antiviral approaches that target multiple aspects of the HBV replication cycle to improve rates of functional cure are urgently required. HBV RNA represents a novel therapeutic target. Here, we programmed CRISPR-Cas13b endonuclease to specifically target the HBV pregenomic RNA and viral mRNAs in a novel approach to reduce HBV replication and protein expression. METHODS Cas13b CRISPR RNAs (crRNAs) were designed to target multiple regions of HBV pregenomic RNA. Mammalian cells transfected with replication competent wild-type HBV DNA of different genotypes, a HBV-expressing stable cell line, a HBV infection model and a hepatitis B surface antigen (HBsAg)-expressing stable cell line were transfected with PspCas13b-BFP (blue fluorescent protein) and crRNA plasmids, and the impact on HBV replication and protein expression was measured. Wild-type HBV DNA, PspCas13b-BFP and crRNA plasmids were simultaneously hydrodynamically injected into mice, and serum HBsAg was measured. PspCas13b mRNA and crRNA were also delivered to a HBsAg-expressing stable cell line via lipid nanoparticles and the impact on secreted HBsAg determined. RESULTS Our HBV-targeting crRNAs strongly suppressed HBV replication and protein expression in mammalian cells by up to 96% (p <0.0001). HBV protein expression was also reduced in a HBV-expressing stable cell line and in the HBV infection model. CRISPR-Cas13b crRNAs reduced HBsAg expression by 50% (p <0.0001) in vivo. Lipid nanoparticle-encapsulated PspCas13b mRNA reduced secreted HBsAg by 87% (p = 0.0168) in a HBsAg-expressing stable cell line. CONCLUSIONS Together, these results show that CRISPR-Cas13b can be programmed to specifically target and degrade HBV RNAs to reduce HBV replication and protein expression, demonstrating its potential as a novel therapeutic option for chronic HBV infection. IMPACT AND IMPLICATIONS Owing to the limitations of current antiviral therapies for hepatitis B, there is an urgent need for new treatments that target multiple aspects of the HBV replication cycle to improve rates of functional cure. Here, we present CRISPR-Cas13b as a novel strategy to target HBV replication and protein expression, paving the way for its development as a potential new treatment option for patients living with chronic hepatitis B.
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Affiliation(s)
- Laura C McCoullough
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Department of Microbiology and Immunology, The University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Mohamed Fareh
- Cancer Immunology Program, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Australia
| | - Wenxin Hu
- Cancer Immunology Program, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Australia
| | - Vitina Sozzi
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Christina Makhlouf
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Yianni Droungas
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Department of Microbiology and Immunology, The University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Chee Leng Lee
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Mina Takawy
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Department of Infectious Diseases, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Stewart A Fabb
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Thomas J Payne
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Colin W Pouton
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Hans J Netter
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Sharon R Lewin
- Department of Infectious Diseases, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Victorian Infectious Diseases Service, Royal Melbourne Hospital at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Department of Infectious Diseases, Alfred Hospital and Monash University, Melbourne, Australia
| | - Damian Fj Purcell
- Department of Microbiology and Immunology, The University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Jacinta A Holmes
- Department of Gastroenterology, St. Vincent's Hospital, Melbourne, Victoria, Australia
| | - Joseph A Trapani
- Cancer Immunology Program, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Australia
| | - Margaret Littlejohn
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Department of Infectious Diseases, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Peter A Revill
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia; Department of Infectious Diseases, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia.
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Keeshan A, da Silva CF, Vachon A, Giles E, Osiowy C, Coffin C, Cooper CL. Hepatitis B Virus Genotype Influence on Virological and Enzymatic Measures over Time-A Retrospective Longitudinal Cohort Study. J Clin Med 2023; 12:6807. [PMID: 37959272 PMCID: PMC10649073 DOI: 10.3390/jcm12216807] [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: 09/14/2023] [Revised: 10/12/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023] Open
Abstract
HBV is a hepatotropic virus with multiple genotypes. It is uncertain if specific genotype(s) influence virological measures and/or liver markers over time. It is unclear whether nucleos(t)ide analogue therapy response is influenced by genotype. In this retrospective longitudinal study, we utilized data from The Ottawa Hospital Viral Hepatitis Program (TOHVHP) to evaluate the role of HBV genotype on viral load, liver enzymatic levels, fibrosis progression, and parenchymal inflammation and steatosis over time. HBV DNA, ALT, and AST levels, as well as transient elastography scores for fibrosis (E) and inflammation/steatosis (CAP), were modeled using mixed-effects linear regression. Interaction terms between HBV genotype and time were included to investigate if there was a difference in trends between genotypes. A total of 393 HBV patients infected with genotypes A-E were included. The mean age was 44.4 years, and 56% were male. Asian (50.5%), Black (29.1%), and White (6.4%) patients were well-represented. By multivariate analysis, we found no evidence that the trajectories of these commonly measured viral or liver measures varied over time by HBV genotype in those receiving HBV nucleos(t)ides and in those not on antiviral therapy.
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Affiliation(s)
- Alexa Keeshan
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON K1Y 4E9, Canada
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | | | - Alicia Vachon
- Faculty of Medicine, University of Ottawa, Ottawa, ON K1N 6N5, Canada
- Division of Infectious Diseases, Department of Medicine, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Elizabeth Giles
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB R2C 3A9, Canada
| | - Carla Osiowy
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB R2C 3A9, Canada
| | - Carla Coffin
- Department of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Curtis L. Cooper
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON K1Y 4E9, Canada
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON K1N 6N5, Canada
- Faculty of Medicine, University of Ottawa, Ottawa, ON K1N 6N5, Canada
- Division of Infectious Diseases, Department of Medicine, University of Ottawa, Ottawa, ON K1N 6N5, Canada
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Vachon A, Seo GE, Patel NH, Coffin CS, Marinier E, Eyras E, Osiowy C. Hepatitis B virus serum RNA transcript isoform composition and proportion in chronic hepatitis B patients by nanopore long-read sequencing. Front Microbiol 2023; 14:1233178. [PMID: 37645229 PMCID: PMC10461054 DOI: 10.3389/fmicb.2023.1233178] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 07/31/2023] [Indexed: 08/31/2023] Open
Abstract
Introduction Serum hepatitis B virus (HBV) RNA is a promising new biomarker to manage and predict clinical outcomes of chronic hepatitis B (CHB) infection. However, the HBV serum transcriptome within encapsidated particles, which is the biomarker analyte measured in serum, remains poorly characterized. This study aimed to evaluate serum HBV RNA transcript composition and proportionality by PCR-cDNA nanopore sequencing of samples from CHB patients having varied HBV genotype (gt, A to F) and HBeAg status. Methods Longitudinal specimens from 3 individuals during and following pregnancy (approximately 7 months between time points) were also investigated. HBV RNA extracted from 16 serum samples obtained from 13 patients (73.3% female, 84.6% Asian) was sequenced and serum HBV RNA isoform detection and quantification were performed using three bioinformatic workflows; FLAIR, RATTLE, and a GraphMap-based workflow within the Galaxy application. A spike-in RNA variant (SIRV) control mix was used to assess run quality and coverage. The proportionality of transcript isoforms was based on total HBV reads determined by each workflow. Results All chosen isoform detection workflows showed high agreement in transcript proportionality and composition for most samples. HBV pregenomic RNA (pgRNA) was the most frequently observed transcript isoform (93.8% of patient samples), while other detected transcripts included pgRNA spliced variants, 3' truncated variants and HBx mRNA, depending on the isoform detection method. Spliced variants of pgRNA were primarily observed in HBV gtB, C, E, or F-infected patients, with the Sp1 spliced variant detected most frequently. Twelve other pgRNA spliced variant transcripts were identified, including 3 previously unidentified transcripts, although spliced isoform identification was very dependent on the workflow used to analyze sequence data. Longitudinal sampling among pregnant and post-partum antiviral-treated individuals showed increasing proportions of 3' truncated pgRNA variants over time. Conclusions This study demonstrated long-read sequencing as a promising tool for the characterization of the serum HBV transcriptome. However, further studies are needed to better understand how serum HBV RNA isoform type and proportion are linked to CHB disease progression and antiviral treatment response.
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Affiliation(s)
- Alicia Vachon
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB, Canada
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Grace E. Seo
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB, Canada
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Nishi H. Patel
- Department of Medicine and Department of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Carla S. Coffin
- Department of Medicine and Department of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Eric Marinier
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Eduardo Eyras
- EMBL Australia Partner Laboratory Network at the Australian National University, Canberra, ACT, Australia
- The John Curtin School of Medical Research, ANU College of Health and Medicine, Canberra, ACT, Australia
- Catalan Institution for Research and Advanced Studies, Barcelona, Spain
- Hospital del Mar Medical Research Institute, Barcelona, Spain
| | - Carla Osiowy
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB, Canada
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
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Sozzi V, McCoullough L, Mason H, Littlejohn M, Revill P. The in vitro replication phenotype of hepatitis B virus (HBV) splice variant Sp1. Virology 2022; 574:65-70. [DOI: 10.1016/j.virol.2022.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 07/08/2022] [Accepted: 07/09/2022] [Indexed: 11/30/2022]
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Maepa MB, Ely A, Kramvis A, Bloom K, Naidoo K, Simani OE, Maponga TG, Arbuthnot P. Hepatitis B Virus Research in South Africa. Viruses 2022; 14:v14091939. [PMID: 36146747 PMCID: PMC9503375 DOI: 10.3390/v14091939] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 08/11/2022] [Accepted: 08/26/2022] [Indexed: 11/18/2022] Open
Abstract
Despite being vaccine-preventable, hepatitis B virus (HBV) infection remains the seventh leading cause of mortality in the world. In South Africa (SA), over 1.9 million people are chronically infected with HBV, and 70% of all Black chronic carriers are infected with HBV subgenotype A1. The virus remains a significant burden on public health in SA despite the introduction of an infant immunization program implemented in 1995 and the availability of effective treatment for chronic HBV infection. In addition, the high prevalence of HIV infection amplifies HBV replication, predisposes patients to chronicity, and complicates management of the infection. HBV research has made significant progress leading to better understanding of HBV epidemiology and management challenges in the SA context. This has led to recent revision of the national HBV infection management guidelines. Research on developing new vaccines and therapies is underway and progress has been made with designing potentially curative gene therapies against HBV. This review summarizes research carried out in SA on HBV molecular biology, epidemiology, treatment, and vaccination strategies.
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Affiliation(s)
- Mohube B. Maepa
- Wits/SAMRC Antiviral Gene Therapy Research Unit, Faculty of Health Sciences, Infectious Diseases and Oncology Research Institute (IDORI), University of the Witwatersrand, Johannesburg 2000, South Africa
- Correspondence:
| | - Abdullah Ely
- Wits/SAMRC Antiviral Gene Therapy Research Unit, Faculty of Health Sciences, Infectious Diseases and Oncology Research Institute (IDORI), University of the Witwatersrand, Johannesburg 2000, South Africa
| | - Anna Kramvis
- Hepatitis Diversity Research Unit, Department of Internal Medicine, Faculty of Health Sciences, School of Clinical Medicine, University of the Witwatersrand, Johannesburg 2000, South Africa
| | - Kristie Bloom
- Wits/SAMRC Antiviral Gene Therapy Research Unit, Faculty of Health Sciences, Infectious Diseases and Oncology Research Institute (IDORI), University of the Witwatersrand, Johannesburg 2000, South Africa
| | - Kubendran Naidoo
- Wits/SAMRC Antiviral Gene Therapy Research Unit, Faculty of Health Sciences, Infectious Diseases and Oncology Research Institute (IDORI), University of the Witwatersrand, Johannesburg 2000, South Africa
- National Health Laboratory Service, Johannesburg 2000, South Africa
| | - Omphile E. Simani
- HIV and Hepatitis Research Unit, Department of Virology, Sefako Makgatho Health Sciences University, Pretoria 0204, South Africa
| | - Tongai G. Maponga
- Division of Medical Virology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 7602, South Africa
| | - Patrick Arbuthnot
- Wits/SAMRC Antiviral Gene Therapy Research Unit, Faculty of Health Sciences, Infectious Diseases and Oncology Research Institute (IDORI), University of the Witwatersrand, Johannesburg 2000, South Africa
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Elizalde MM, Tadey L, Mammana L, Quarleri JF, Campos RH, Flichman DM. Biological Characterization of Hepatitis B virus Genotypes: Their Role in Viral Replication and Antigen Expression. Front Microbiol 2021; 12:758613. [PMID: 34803982 PMCID: PMC8600256 DOI: 10.3389/fmicb.2021.758613] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Accepted: 10/13/2021] [Indexed: 01/12/2023] Open
Abstract
Hepatitis B virus (HBV) inter-host evolution has resulted in genomic diversification reflected in the existence of nine genotypes (A-I) and numerous subgenotypes. There is growing evidence that genotypes influence HBV natural history, clinical outcomes, and treatment response. However, the biological characteristics underlying these differences have not yet been established. By transfecting HuH-7 cells with unit-length constructs of genotypes A2, B2, C1, D1, and F1b, we identified major differences in HBV replicative capacity and antigen expression across genotypes. Genotypes B2 and F1b showed a 2-fold increase in cccDNA levels compared to the other genotypes (p<0.005). Genotype A2 expressed the lowest pgRNA levels, with a 70-fold decrease in relation to the other genotypes (p<0.0001), while genotype B2 showed the lowest Precore RNA levels, with a 100-fold reduction compared to genotype A2 (p<0.0001). The highest intracellular HBV DNA levels were observed for genotype B2 and the lowest for genotypes A2 and C1 (p<0.0001). Regarding antigen expression, genotype F1b secreted the highest HBsAg levels and genotype D1 the lowest (p<0.0001), while genotypes A2 and B2 showed the highest intracellular HBsAg levels (p<0.0001). Interestingly, genotype C1 secreted the highest HBeAg levels, while genotype A2 showed the highest intracellular levels (p<0.0001). Finally, the analysis of the intra/extracellular antigen ratios revealed that most genotypes retained intracellularly 5-20% of the antigens, except the genotype A2 that retained 50% of the total expressed antigens. In conclusion, this study provides new insights into the biological characteristics of HBV genotypes, being the first study to comparatively analyze European (A and D) and Asian (B and C) genotypes with the Latin American (F) genotype. The differences in HBV replication and antigen expression might contribute to understand the differential role of genotypes in pathogenesis.
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Affiliation(s)
- María Mercedes Elizalde
- Instituto de Investigaciones Biomédicas en Retrovirus y Sida (INBIRS), CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Luciana Tadey
- Unidad de Virología, Hospital de Infecciosas "Francisco J. Muñiz", Buenos Aires, Argentina
| | - Lilia Mammana
- Unidad de Virología, Hospital de Infecciosas "Francisco J. Muñiz", Buenos Aires, Argentina
| | - Jorge Fabián Quarleri
- Instituto de Investigaciones Biomédicas en Retrovirus y Sida (INBIRS), CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Rodolfo Héctor Campos
- Departamento de Microbiología, Inmunología, Biotecnología y Genética, Cátedra de Virología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Diego Martín Flichman
- Instituto de Investigaciones Biomédicas en Retrovirus y Sida (INBIRS), CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
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In Vivo Modelling of Hepatitis B Virus Subgenotype A1 Replication Using Adeno-Associated Viral Vectors. Viruses 2021; 13:v13112247. [PMID: 34835053 PMCID: PMC8618177 DOI: 10.3390/v13112247] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 10/30/2021] [Accepted: 11/04/2021] [Indexed: 12/23/2022] Open
Abstract
The paucity of animal models that simulate the replication of the hepatitis B virus (HBV) is an impediment to advancing new anti-viral treatments. The work reported here employed recombinant adeno-associated viruses (AAVs) to model HBV subgenotype A1 and subgenotype D3 replication in vitro and in vivo. Infection with subgenotype A1 is endemic to parts of sub-Saharan Africa, and it is associated with a high risk of hepatocellular carcinoma. Recombinant AAV serotype 2 (AAV2) and 8 (AAV8) vectors bearing greater-than-genome-length sequences of HBV DNA from subgenotype A1 and D3, were produced. Transduced liver-derived cultured cells produced HBV surface antigen and core antigen. Administration of AAV8 carrying HBV subgenotype A1 genome (AAV8-A1) to mice resulted in the sustained production of HBV replication markers over a six-month period, without elevated inflammatory cytokines, expression of interferon response genes or alanine transaminase activity. Markers of replication were generally higher in animals treated with subgenotype D3 genome-bearing AAVs than in those receiving the subgenotype A1-genome-bearing vectors. To validate the use of the AAV8-A1 murine model for anti-HBV drug development, the efficacy of anti-HBV artificial primary-microRNAs was assessed. Significant silencing of HBV markers was observed over a 6-month period after administering AAVs. These data indicate that AAVs conveniently and safely recapitulate the replication of different HBV subgenotypes, and the vectors may be used to assess antivirals’ potency.
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In Vitro Systems for Studying Different Genotypes/Sub-Genotypes of Hepatitis B Virus: Strengths and Limitations. Viruses 2020; 12:v12030353. [PMID: 32210021 PMCID: PMC7150782 DOI: 10.3390/v12030353] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 03/04/2020] [Accepted: 03/06/2020] [Indexed: 12/11/2022] Open
Abstract
Hepatitis B virus (HBV) infects the liver resulting in end stage liver disease, cirrhosis, and hepatocellular carcinoma. Despite an effective vaccine, HBV poses a serious health problem globally, accounting for 257 million chronic carriers. Unique features of HBV, including its narrow virus-host range and its hepatocyte tropism, have led to major challenges in the development of suitable in vivo and in vitro model systems to recapitulate the HBV replication cycle and to test various antiviral strategies. Moreover, HBV is classified into at least nine genotypes and 35 sub-genotypes with distinct geographical distributions and prevalence, which have different natural histories of infection, clinical manifestation, and response to current antiviral agents. Here, we review various in vitro systems used to study the molecular biology of the different (sub)genotypes of HBV and their response to antiviral agents, and we discuss their strengths and limitations. Despite the advances made, no system is ideal for pan-genotypic HBV research or drug development and therefore further improvement is required. It is necessary to establish a centralized repository of HBV-related generated materials, which are readily accessible to HBV researchers, with international collaboration toward advancement and development of in vitro model systems for testing new HBV antivirals to ensure their pan-genotypic and/or customized activity.
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