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Gonçalves BC, Lopes Barbosa MG, Silva Olak AP, Belebecha Terezo N, Nishi L, Watanabe MA, Marinello P, Zendrini Rechenchoski D, Dejato Rocha SP, Faccin-Galhardi LC. Antiviral therapies: advances and perspectives. Fundam Clin Pharmacol 2020; 35:305-320. [PMID: 33011993 PMCID: PMC7675511 DOI: 10.1111/fcp.12609] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/16/2020] [Accepted: 09/28/2020] [Indexed: 12/12/2022]
Abstract
Viral infections cause high morbidity and mortality, threaten public health, and impose a socioeconomic burden. We have seen the recent emergence of SARS‐CoV‐2 (Severe Acute Respiratory Syndrome Coronavirus 2), the causative agent of COVID‐19 that has already infected more than 29 million people, with more than 900 000 deaths since its identification in December 2019. Considering the significant impact of viral infections, research and development of new antivirals and control strategies are essential. In this paper, we summarize 96 antivirals approved by the Food and Drug Administration between 1987 and 2019. Of these, 49 (51%) are used in treatments against human immunodeficiency virus (HIV), four against human papillomavirus, six against cytomegalovirus, eight against hepatitis B virus, five against influenza, six against herpes simplex virus, 17 against hepatitis C virus and one against respiratory syncytial virus. This review also describes future perspectives for new antiviral therapies such as nanotechnologies, monoclonal antibodies and the CRISPR‐Cas system. These strategies are suggested as inhibitors of viral replication by various means, such as direct binding to the viral particle, blocking the infection, changes in intracellular mechanisms or viral genes, preventing replication and virion formation. We also observed that a large number of viral agents have no therapy available and the majority of those approved in the last 32 years are restricted to some groups, especially anti‐HIV. Additionally, the emergence of new viruses and strains resistant to available antivirals has necessitated the formulation of new antivirals.
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Affiliation(s)
- Bruna Carolina Gonçalves
- Departamento de Microbiologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, 86057-970, Brazil
| | - Mário Gabriel Lopes Barbosa
- Departamento de Microbiologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, 86057-970, Brazil
| | - Anna Paula Silva Olak
- Departamento de Microbiologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, 86057-970, Brazil
| | - Natalia Belebecha Terezo
- Departamento de Microbiologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, 86057-970, Brazil
| | - Leticia Nishi
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, 86057-970, Brazil
| | - Maria Angélica Watanabe
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, 86057-970, Brazil
| | - Poliana Marinello
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, 86057-970, Brazil
| | - Daniele Zendrini Rechenchoski
- Departamento de Microbiologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, 86057-970, Brazil
| | - Sergio Paulo Dejato Rocha
- Departamento de Microbiologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, 86057-970, Brazil
| | - Lígia Carla Faccin-Galhardi
- Departamento de Microbiologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, 86057-970, Brazil
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2
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Ezzikouri S, Hoque Kayesh ME, Benjelloun S, Kohara M, Tsukiyama-Kohara K. Targeting Host Innate and Adaptive Immunity to Achieve the Functional Cure of Chronic Hepatitis B. Vaccines (Basel) 2020; 8:vaccines8020216. [PMID: 32403281 PMCID: PMC7349973 DOI: 10.3390/vaccines8020216] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/15/2020] [Accepted: 04/16/2020] [Indexed: 02/06/2023] Open
Abstract
Despite the availability of an effective preventive vaccine for hepatitis B virus (HBV) for over 38 years, chronic HBV (CHB) infection remains a global health burden with around 257 million patients. The ideal treatment goal for CHB infection would be to achieve complete cure; however, current therapies such as peg-interferon and nucleos(t)ide analogs are unable to achieve the functional cure, the newly set target for HBV chronic infection. Considering the fact functional cure has been accepted as an endpoint in the treatment of chronic hepatitis B by scientific committee, the development of alternative therapeutic strategies is urgently needed to functionally cure CHB infection. A promising target for future therapeutic strategies is immune modulation to restore dysfunctional HBV-specific immunity. In this review, we provide an overview of the progress in alternative therapeutic strategies, including immune-based therapeutic approaches that enhance host innate and adaptive immunity to achieve and increase the functional cure from CHB infection.
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Affiliation(s)
- Sayeh Ezzikouri
- Virology Unit, Viral Hepatitis Laboratory, Institut Pasteur du Maroc, Casablanca 20250, Morocco;
- Transboundary Animal Diseases Centre, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan;
- Correspondence: (S.E.); (K.T.-K.); Tel.: +212-5-2243-4470 (S.E.); Tel./Fax: +81-99-285-3589 (K.T.-K.)
| | - Mohammad Enamul Hoque Kayesh
- Transboundary Animal Diseases Centre, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan;
- Department of Microbiology and Public Health, Faculty of Animal Science and Veterinary Medicine, Patuakhali Science and Technology University, Barishal 8210, Bangladesh
| | - Soumaya Benjelloun
- Virology Unit, Viral Hepatitis Laboratory, Institut Pasteur du Maroc, Casablanca 20250, Morocco;
| | - Michinori Kohara
- Department of Microbiology and Cell Biology, The Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan;
| | - Kyoko Tsukiyama-Kohara
- Transboundary Animal Diseases Centre, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan;
- Correspondence: (S.E.); (K.T.-K.); Tel.: +212-5-2243-4470 (S.E.); Tel./Fax: +81-99-285-3589 (K.T.-K.)
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3
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Lee C. Controversial Effects of Vitamin D and Related Genes on Viral Infections, Pathogenesis, and Treatment Outcomes. Nutrients 2020; 12:nu12040962. [PMID: 32235600 PMCID: PMC7230640 DOI: 10.3390/nu12040962] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 03/23/2020] [Accepted: 03/26/2020] [Indexed: 12/11/2022] Open
Abstract
Vitamin D (VD) plays an essential role in mineral homeostasis and bone remodeling. A number of different VD-related genes (VDRG) are required for the metabolic activation of VD and the subsequent induction of its target genes. They include a set of genes that encode for VD-binding protein, metabolic enzymes, and the VD receptor. In addition to its well-characterized skeletal function, the immunoregulatory activities of VD and the related polymorphisms of VDRG have been reported and linked to its therapeutic and preventive actions for the control of several viral diseases. However, in regards to their roles in the progression of viral diseases, inconsistent and, in some cases, contradictory results also exist. To resolve this discrepancy, I conducted an extensive literature search by using relevant keywords on the PubMed website. Based on the volume of hit papers related to a certain viral infection, I summarized and compared the effects of VD and VDRG polymorphism on the infection, pathogenesis, and treatment outcomes of clinically important viral diseases. They include viral hepatitis, respiratory viral infections, acquired immunodeficiency syndrome (AIDS), and other viral diseases, which are caused by herpesviruses, dengue virus, rotavirus, and human papillomavirus. This review will provide the most current information on the nutritional and clinical utilization of VD and VDRG in the management of the key viral diseases. This information should be valuable not only to nutritionists but also to clinicians who wish to provide evidence-based recommendations on the use of VD to virally infected patients.
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Affiliation(s)
- Choongho Lee
- College of Pharmacy, Dongguk University, Goyang 10326, Korea
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4
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CRISPR/Cas9-Based Antiviral Strategy: Current Status and the Potential Challenge. Molecules 2019; 24:molecules24071349. [PMID: 30959782 PMCID: PMC6480260 DOI: 10.3390/molecules24071349] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 03/29/2019] [Accepted: 04/04/2019] [Indexed: 12/15/2022] Open
Abstract
From its unexpected discovery as a bacterial adaptive immune system to its countless applications as one of the most versatile gene-editing tools, the CRISPR/Cas9 system has revolutionized every field of life science. Virology is no exception to this ever-growing list of CRISPR/Cas9-based applications. Direct manipulation of a virus genome by CRISPR/Cas9 has enabled a systematic study of cis-elements and trans-elements encoded in a virus genome. In addition, this virus genome-specific mutagenesis by CRISPR/Cas9 was further funneled into the development of a novel class of antiviral therapy targeting many incurable chronic viral infections. In this review, a general concept on the CRISPR/Cas9-based antiviral strategy will be described first. To understand the current status of the CRISPR/Cas9-based antiviral approach, a series of recently published antiviral studies involving CRISPR/Cas9-mediated control of several clinically-relevant viruses including human immunodeficiency virus, hepatitis B virus, herpesviruses, human papillomavirus, and other viruses will be presented. Lastly, the potential challenge and future prospect for successful clinical translation of this CRISPR/Cas9-based antiviral method will be discussed.
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5
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Mahas A, Mahfouz M. Engineering virus resistance via CRISPR-Cas systems. Curr Opin Virol 2018; 32:1-8. [PMID: 30005359 DOI: 10.1016/j.coviro.2018.06.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 06/25/2018] [Indexed: 12/15/2022]
Abstract
In prokaryotes, CRISPR/Cas adaptive immunity systems target and destroy nucleic acids derived from invading bacteriophages and other foreign genetic elements. In eukaryotes, the native function of these systems has been exploited to combat viruses in mammals and plants. Rewired CRISPR/Cas9 and CRISPR/Cas13 systems have been used to confer resistance against DNA and RNA viruses, respectively. Here, we discuss recent approaches employing CRISPR/Cas systems to combat viruses in eukaryotes, highlight key challenges, and provide future perspectives. Moreover, we discuss the application of CRISPR/Cas systems in genome-wide screens to identify key host factors for virus infection to enhance our understanding of basic virus biology and to identify and study virus-host interactions.
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Affiliation(s)
- Ahmed Mahas
- Laboratory for Genome Engineering, Division of Biological Sciences, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Magdy Mahfouz
- Laboratory for Genome Engineering, Division of Biological Sciences, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
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6
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Durantel D, Kusters I, Louis J, Manel N, Ottenhoff THM, Picot V, Saaadatian-Elahi M. Mechanisms behind TB, HBV, and HIV chronic infections. INFECTION GENETICS AND EVOLUTION 2017; 55:142-150. [PMID: 28919545 DOI: 10.1016/j.meegid.2017.09.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 09/06/2017] [Accepted: 09/08/2017] [Indexed: 12/13/2022]
Abstract
Immune evasion is critical for pathogens to maintain their presence within hosts, giving rise to chronic infections. Here, we examine the immune evasion strategies employed by three pathogens with high medical burden, namely, tuberculosis, HIV and HBV. Establishment of chronic infection by these pathogens is a multi-step process that involves an interplay between restriction factor, innate immunity and adaptive immunity. Engagement of these host defences is intimately linked with specific steps within the pathogen replication cycles. Critical host factors are increasingly recognized to regulate immune evasion and susceptibility to disease. Fuelled by innovative technology development, the understanding of these mechanisms provides critical knowledge for rational design of vaccines and therapeutic immune strategies.
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Affiliation(s)
- David Durantel
- Cancer Research Center of Lyon (CRCL), INSERM, U1052, CNRS, University of Lyon, UMR_5286, LabEx DEVweCAN, Lyon, France
| | - Inca Kusters
- Sanofi Pasteur, 2 Avenue du Pont Pasteur, 69367 Lyon Cedex 07, France
| | - Jacques Louis
- Fondation Mérieux, 17 rue Bourgelat, 69002 Lyon, France
| | - Nicolas Manel
- Immunity and Cancer Department, Institute Curie, PSL Research University, INSERM U932, 75005 Paris, France
| | - Tom H M Ottenhoff
- Group Immunology and Immunogenetics of Bacterial Infectious Diseases, Dept. of Infectious Diseases, Leiden University Medical Center, Bldg. 1, Rm # C-05-43 Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | | | - Mitra Saaadatian-Elahi
- Hospices Civils de Lyon, Groupement Hospitalier Edouard Herriot, 5 Place d'Arsonval, 69437 Lyon Cedex 03, France.
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7
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Molan AM, Hanson HM, Chweya CM, Anderson BD, Starrett GJ, Richards CM, Harris RS. APOBEC3B lysine residues are dispensable for DNA cytosine deamination, HIV-1 restriction, and nuclear localization. Virology 2017; 511:74-81. [PMID: 28841445 DOI: 10.1016/j.virol.2017.08.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 08/14/2017] [Accepted: 08/16/2017] [Indexed: 12/11/2022]
Abstract
The APOBEC3 DNA cytosine deaminase family comprises a fundamental arm of the innate immune response and is best known for retrovirus restriction. Several APOBEC3 enzymes restrict HIV-1 and related retroviruses by deaminating viral cDNA cytosines to uracils compromising viral genomes. Human APOBEC3B (A3B) shows strong virus restriction activities in a variety of experimental systems, and is subjected to tight post-translational regulation evidenced by cell-specific HIV-1 restriction activity and active nuclear import. Here we ask whether lysines and/or lysine post-translational modifications are required for these A3B activities. A lysine-free derivative of human A3B was constructed and shown to be indistinguishable from the wild-type enzyme in DNA cytosine deamination, HIV-1 restriction, and nuclear localization activities. However, lysine loss did render the protein resistant to degradation by SIV Vif. Taken together, we conclude that lysine side chains and modifications thereof are unlikely to be central to A3B function or regulation in human cells.
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Affiliation(s)
- Amy M Molan
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Heather M Hanson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Cynthia M Chweya
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Brett D Anderson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Gabriel J Starrett
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Christopher M Richards
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA; Howard Hughes Medical Institute, University of Minnesota, Minneapolis, MN 55455, USA.
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NgAgo-gDNA system efficiently suppresses hepatitis B virus replication through accelerating decay of pregenomic RNA. Antiviral Res 2017; 145:20-23. [PMID: 28709658 DOI: 10.1016/j.antiviral.2017.07.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 06/21/2017] [Accepted: 07/10/2017] [Indexed: 11/21/2022]
Abstract
Covalently closed circular DNA (cccDNA) in the hepatocytes nucleus is responsible for persistent infection of Hepatitis B virus (HBV). Current antiviral therapy drugs nucleos(t)ide analogs or interferon fail to eradicate HBV cccDNA. Genome editing technique provides an effective approach for HBV treatment through targeting viral cccDNA. Natronobacterium gregoryi Argonaute (NgAgo)-guide DNA (gDNA) system with powerful genome editing prompts us to explore its application in inhibiting HBV replication. Preliminary function verification indicated that NgAgo/EGFP-gDNA obviously inhibited EGFP expression. To further explore the potential role of NgAgo in restricting HBV replication, 10 of gDNAs targeting the critical region of viral genome were designed, only S-142, P-263 and P-2166 gDNAs led to significant inhibition on HBsAg, HBeAg and pregenomic RNA (pgRNA) level in Huh7 and HepG2 cells transfected with pcDNA-HBV1.1 plasmid. Similar results were also found in HBV infected HLCZ01 cells and Huh7-NTCP cells. However, we failed to detect any DNA editing in S-142, P-263 and P-2166 targeting region through T7E1 assay and Sanger sequencing. Remarkably, we found that NgAgo/P-2166 significantly accelerated the decay of viral pgRNA. Taken together, our results firstly demonstrate the potential of NgAgo/gDNA in inhibiting HBV replication through accelerating pgRNA degradation, but not DNA editing.
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Jubair L, McMillan NAJ. The Therapeutic Potential of CRISPR/Cas9 Systems in Oncogene-Addicted Cancer Types: Virally Driven Cancers as a Model System. MOLECULAR THERAPY-NUCLEIC ACIDS 2017; 8:56-63. [PMID: 28918056 PMCID: PMC5485762 DOI: 10.1016/j.omtn.2017.06.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 06/03/2017] [Accepted: 06/09/2017] [Indexed: 12/30/2022]
Abstract
The field of gene editing is undergoing unprecedented growth. The first ex vivo human clinical trial in China started in 2016, more than 1000 US patents have been filed, and there is exponential growth in publications. The ability to edit genes with high fidelity is promising for the development of new treatments for a range of diseases, particularly inherited conditions, infectious diseases, and cancers. For cancer, a major issue is the identification of driver mutations and oncogenes to target for therapeutic effect, and this requires the development of robust models with which to prove their efficacy. The challenge is that there is rarely a single critical gene. However, virally driven cancers, in which cells are addicted to the expression of a single viral oncogene in some cases, may serve as model systems for CRISPR/Cas therapies, as they did for RNAi. These models and systems offer an excellent opportunity to test both preclinical models and clinical conditions to examine the effectiveness of gene editing, and here we review the options and offer a way forward.
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Affiliation(s)
- Luqman Jubair
- School of Medical Sciences, Griffith University, Gold Coast, QLD 4222, Australia.
| | - Nigel A J McMillan
- School of Medical Sciences, Griffith University, Gold Coast, QLD 4222, Australia; Menzies Health Institute Queensland, Griffith University, Gold Coast, QLD 4222, Australia; Diamantina Institute, University of Queensland, Brisbane St. Lucia, QLD 4072, Australia
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10
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Lin G, Zhang K, Li J. Application of CRISPR/Cas9 Technology to HBV. Int J Mol Sci 2015; 16:26077-86. [PMID: 26540039 PMCID: PMC4661809 DOI: 10.3390/ijms161125950] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 10/25/2015] [Accepted: 10/26/2015] [Indexed: 12/26/2022] Open
Abstract
More than 240 million people around the world are chronically infected with hepatitis B virus (HBV). Nucleos(t)ide analogs and interferon are the only two families of drugs to treat HBV currently. However, none of these anti-virals directly target the stable nuclear covalently closed circular DNA (cccDNA), which acts as a transcription template for viral mRNA and pre-genomic RNA synthesis and secures virus persistence. Thus, the fact that only a small number of patients treated achieve sustained viral response (SVR) or cure, highlights the need for new therapies against HBV. The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 gene editing system can specifically target the conserved regions of the HBV genome. This results in robust viral suppression and provides a promising tool for eradicating the virus. In this review, we discuss the function and application of the CRISPR/Cas9 system as a novel therapy for HBV.
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Affiliation(s)
- Guigao Lin
- National Center for Clinical Laboratories, Beijing Hospital, Beijing 100730, China.
| | - Kuo Zhang
- National Center for Clinical Laboratories, Beijing Hospital, Beijing 100730, China.
| | - Jinming Li
- National Center for Clinical Laboratories, Beijing Hospital, Beijing 100730, China.
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Abstract
INTRODUCTION The hepatitis B virus (HBV) causes chronic hepatitis B (CHB) in ∼350 million people worldwide who have an increased risk of end-stage liver disease and/or hepatocellular carcinoma. SOURCES OF DATA Several peer-reviewed papers featuring new approaches to anti-HBV management. Additionally, we also reviewed recent abstract presentations at international congresses. AREAS OF AGREEMENT There has been great progress in CHB therapy with the development of standard and pegylated interferon (i.e. PEG-IFN) as well as nucleos/tide analogs (NAs). IFN has both antiviral and immunomodulatory effects and through immune-mediated destruction of infected hepatocytes offers the possibility of finite therapy. However, this 'killing for a cure' antiviral strategy may not be tolerated in many, especially in cirrhotic patients. NAs inhibit viral reverse transcriptase, have few side effects and prevent liver disease progression, but cannot offer a cure as they have little effect on the resilient HBV covalently closed circular DNA (cccDNA) intermediate. Moreover, NAs such as tenofovir and entecavir offer a high genetic barrier to resistance, but are expensive and not readily available in many global regions. GROWING POINTS Despite significant treatment advances, there is increased recognition of the need for improved anti-HBV treatments, and new virologic tests for monitoring treatment response. AREAS OF CONTROVERSY The role of quantitative hepatitis B surface antigen, intrahepatic cccDNA levels and viral genotype in selecting treatment candidates and refining NA stopping rules. AREAS TIMELY FOR DEVELOPING NEW RESEARCH Potential new therapies include viral entry inhibitors, RNA interference technologies (i.e. RNAi) and small molecules that modulate cccDNA transcription, as well as novel immunomodulatory therapies to boost HBV-specific T cell responses. The ultimate goal of new tests and anti-HBV therapies is to reduce the burden and expense of life-long CHB treatment, as 'only diamonds are forever'.
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Affiliation(s)
- Carla S Coffin
- Liver Unit, Division of Gastroenterology and Hepatology, Department of Medicine, Faculty of Medicine, University of Calgary, Calgary, AB, Canada
| | - Samuel S Lee
- Liver Unit, Division of Gastroenterology and Hepatology, Department of Medicine, Faculty of Medicine, University of Calgary, Calgary, AB, Canada
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12
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Guo JT, Guo H. Metabolism and function of hepatitis B virus cccDNA: Implications for the development of cccDNA-targeting antiviral therapeutics. Antiviral Res 2015; 122:91-100. [PMID: 26272257 DOI: 10.1016/j.antiviral.2015.08.005] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 08/07/2015] [Indexed: 02/07/2023]
Abstract
Persistent hepatitis B virus (HBV) infection relies on the stable maintenance and proper functioning of a nuclear episomal form of the viral genome called covalently closed circular (ccc) DNA. One of the major reasons for the failure of currently available antiviral therapeutics to achieve a cure of chronic HBV infection is their inability to eradicate or inactivate cccDNA. In this review article, we summarize our current understanding of cccDNA metabolism in hepatocytes and the modulation of cccDNA by host pathophysiological and immunological cues. Perspectives on the future investigation of cccDNA biology, as well as strategies and progress in therapeutic elimination and/or transcriptional silencing of cccDNA through rational design and phenotypic screenings, are also discussed. This article forms part of a symposium in Antiviral Research on "An unfinished story: from the discovery of the Australia antigen to the development of new curative therapies for hepatitis B."
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Affiliation(s)
- Ju-Tao Guo
- Baruch S. Blumberg Institute, Hepatitis B Foundation, Doylestown, PA 18902, USA.
| | - Haitao Guo
- Department of Microbiology and Immunology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202, USA.
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13
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Ramanan V, Shlomai A, Cox DB, Schwartz RE, Michailidis E, Bhatta A, Scott DA, Zhang F, Rice CM, Bhatia SN. CRISPR/Cas9 cleavage of viral DNA efficiently suppresses hepatitis B virus. Sci Rep 2015; 5:10833. [PMID: 26035283 PMCID: PMC4649911 DOI: 10.1038/srep10833] [Citation(s) in RCA: 219] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 04/29/2015] [Indexed: 02/07/2023] Open
Abstract
Chronic hepatitis B virus (HBV) infection is prevalent, deadly, and seldom cured due to the persistence of viral episomal DNA (cccDNA) in infected cells. Newly developed genome engineering tools may offer the ability to directly cleave viral DNA, thereby promoting viral clearance. Here, we show that the CRISPR/Cas9 system can specifically target and cleave conserved regions in the HBV genome, resulting in robust suppression of viral gene expression and replication. Upon sustained expression of Cas9 and appropriately chosen guide RNAs, we demonstrate cleavage of cccDNA by Cas9 and a dramatic reduction in both cccDNA and other parameters of viral gene expression and replication. Thus, we show that directly targeting viral episomal DNA is a novel therapeutic approach to control the virus and possibly cure patients.
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Affiliation(s)
- Vyas Ramanan
- Department of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Amir Shlomai
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10065, USA
| | - David B.T. Cox
- Department of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Broad Institute, Cambridge, MA 02139, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Robert E. Schwartz
- Department of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA
- Division of Gastroenterology and Hepatology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Eleftherios Michailidis
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10065, USA
| | - Ankit Bhatta
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10065, USA
| | - David A. Scott
- Broad Institute, Cambridge, MA 02139, USA
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Feng Zhang
- Department of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Broad Institute, Cambridge, MA 02139, USA
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Charles M. Rice
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10065, USA
| | - Sangeeta N. Bhatia
- Department of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Broad Institute, Cambridge, MA 02139, USA
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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