Improved Specificity and Safety of Anti-Hepatitis B Virus TALENs Using Obligate Heterodimeric <i>Fok</i>I Nuclease Domains
Persistent hepatitis B virus (HBV) infection remains a serious medical problem worldwide, with an estimated global burden of 257 million carriers. Prophylactic and therapeutic interventions, in the form of a vaccine, immunomodulators, and nucleotide and nucleoside analogs, are available. Vaccination...
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| Format: | Article |
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MDPI AG
2021-07-01
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| Series: | Viruses |
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| Online Access: | https://www.mdpi.com/1999-4915/13/7/1344 |
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| author | Tiffany Smith Prashika Singh Kay Ole Chmielewski Kristie Bloom Toni Cathomen Patrick Arbuthnot Abdullah Ely |
| author_facet | Tiffany Smith Prashika Singh Kay Ole Chmielewski Kristie Bloom Toni Cathomen Patrick Arbuthnot Abdullah Ely |
| author_sort | Tiffany Smith |
| collection | DOAJ |
| description | Persistent hepatitis B virus (HBV) infection remains a serious medical problem worldwide, with an estimated global burden of 257 million carriers. Prophylactic and therapeutic interventions, in the form of a vaccine, immunomodulators, and nucleotide and nucleoside analogs, are available. Vaccination, however, offers no therapeutic benefit to chronic sufferers and has had a limited impact on infection rates. Although immunomodulators and nucleotide and nucleoside analogs have been licensed for treatment of chronic HBV, cure rates remain low. Transcription activator-like effector nucleases (TALENs) designed to bind and cleave viral DNA offer a novel therapeutic approach. Importantly, TALENs can target covalently closed circular DNA (cccDNA) directly with the potential of permanently disabling this important viral replicative intermediate. Potential off-target cleavage by engineered nucleases leading to toxicity presents a limitation of this technology. To address this, in the context of HBV gene therapy, existing TALENs targeting the viral <i>core</i> and <i>surface</i> open reading frames were modified with second- and third-generation <i>Fok</i>I nuclease domains. As obligate heterodimers these TALENs prevent target cleavage as a result of <i>Fok</i>I homodimerization. Second-generation obligate heterodimeric TALENs were as effective at silencing viral gene expression as first-generation counterparts and demonstrated an improved specificity in a mouse model of HBV replication. |
| first_indexed | 2024-03-10T09:20:56Z |
| format | Article |
| id | doaj.art-937c052fb6e244cdae041dbe15844907 |
| institution | Directory Open Access Journal |
| issn | 1999-4915 |
| language | English |
| last_indexed | 2024-03-10T09:20:56Z |
| publishDate | 2021-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Viruses |
| spelling | doaj.art-937c052fb6e244cdae041dbe158449072023-11-22T05:14:30ZengMDPI AGViruses1999-49152021-07-01137134410.3390/v13071344Improved Specificity and Safety of Anti-Hepatitis B Virus TALENs Using Obligate Heterodimeric <i>Fok</i>I Nuclease DomainsTiffany Smith0Prashika Singh1Kay Ole Chmielewski2Kristie Bloom3Toni Cathomen4Patrick Arbuthnot5Abdullah Ely6Wits/SAMRC Antiviral Gene Therapy Research Unit, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South AfricaWits/SAMRC Antiviral Gene Therapy Research Unit, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South AfricaInstitute for Transfusion Medicine and Gene Therapy, Medical Center-University of Freiburg & Medical Faculty, University of Freiburg, 79106 Freiburg, GermanyWits/SAMRC Antiviral Gene Therapy Research Unit, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South AfricaInstitute for Transfusion Medicine and Gene Therapy, Medical Center-University of Freiburg & Medical Faculty, University of Freiburg, 79106 Freiburg, GermanyWits/SAMRC Antiviral Gene Therapy Research Unit, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South AfricaWits/SAMRC Antiviral Gene Therapy Research Unit, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South AfricaPersistent hepatitis B virus (HBV) infection remains a serious medical problem worldwide, with an estimated global burden of 257 million carriers. Prophylactic and therapeutic interventions, in the form of a vaccine, immunomodulators, and nucleotide and nucleoside analogs, are available. Vaccination, however, offers no therapeutic benefit to chronic sufferers and has had a limited impact on infection rates. Although immunomodulators and nucleotide and nucleoside analogs have been licensed for treatment of chronic HBV, cure rates remain low. Transcription activator-like effector nucleases (TALENs) designed to bind and cleave viral DNA offer a novel therapeutic approach. Importantly, TALENs can target covalently closed circular DNA (cccDNA) directly with the potential of permanently disabling this important viral replicative intermediate. Potential off-target cleavage by engineered nucleases leading to toxicity presents a limitation of this technology. To address this, in the context of HBV gene therapy, existing TALENs targeting the viral <i>core</i> and <i>surface</i> open reading frames were modified with second- and third-generation <i>Fok</i>I nuclease domains. As obligate heterodimers these TALENs prevent target cleavage as a result of <i>Fok</i>I homodimerization. Second-generation obligate heterodimeric TALENs were as effective at silencing viral gene expression as first-generation counterparts and demonstrated an improved specificity in a mouse model of HBV replication.https://www.mdpi.com/1999-4915/13/7/1344HBVcccDNAobligate heterodimeric TALENsSharkey |
| spellingShingle | Tiffany Smith Prashika Singh Kay Ole Chmielewski Kristie Bloom Toni Cathomen Patrick Arbuthnot Abdullah Ely Improved Specificity and Safety of Anti-Hepatitis B Virus TALENs Using Obligate Heterodimeric <i>Fok</i>I Nuclease Domains Viruses HBV cccDNA obligate heterodimeric TALENs Sharkey |
| title | Improved Specificity and Safety of Anti-Hepatitis B Virus TALENs Using Obligate Heterodimeric <i>Fok</i>I Nuclease Domains |
| title_full | Improved Specificity and Safety of Anti-Hepatitis B Virus TALENs Using Obligate Heterodimeric <i>Fok</i>I Nuclease Domains |
| title_fullStr | Improved Specificity and Safety of Anti-Hepatitis B Virus TALENs Using Obligate Heterodimeric <i>Fok</i>I Nuclease Domains |
| title_full_unstemmed | Improved Specificity and Safety of Anti-Hepatitis B Virus TALENs Using Obligate Heterodimeric <i>Fok</i>I Nuclease Domains |
| title_short | Improved Specificity and Safety of Anti-Hepatitis B Virus TALENs Using Obligate Heterodimeric <i>Fok</i>I Nuclease Domains |
| title_sort | improved specificity and safety of anti hepatitis b virus talens using obligate heterodimeric i fok i i nuclease domains |
| topic | HBV cccDNA obligate heterodimeric TALENs Sharkey |
| url | https://www.mdpi.com/1999-4915/13/7/1344 |
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