title: Inactivation of hepatitis B virus replication in cultured cells and in vivo with engineered transcription activator-like effector nucleases.
abstract: Chronic hepatitis B virus (HBV) infection remains an important global health problem. Stability of the episomal covalently closed circular HBV DNA (cccDNA) is largely responsible for the modest curative efficacy of available therapy. Since licensed anti-HBV drugs have a post-transcriptional mechanism of action, disabling cccDNA is potentially of therapeutic benefit. To develop this approach, we engineered mutagenic transcription activator-like effector nucleases (TALENs) that target four HBV-specific sites within the viral genome. TALENs with cognate sequences in the S or C open-reading frames (ORFs) efficiently disrupted sequences at the intended sites and suppressed markers of viral replication. Following triple transfection of cultured HepG2.2.15 cells under mildly hypothermic conditions, the S TALEN caused targeted mutation in ~35% of cccDNA molecules. Markers of viral replication were also inhibited in vivo in a murine hydrodynamic injection model of HBV replication. HBV target sites within S and C ORFs of the injected HBV DNA were mutated without evidence of toxicity. These findings are the first to demonstrate a targeted nuclease-mediated disruption of HBV cccDNA. Efficacy in vivo also indicates that these engineered nucleases have potential for use in treatment of chronic HBV infection.
authors.affiliation: Antiviral Gene Therapy Research Unit, School of Pathology and African Network for Drugs and Diagnostics Innovation (ANDI) Centre of Excellence, Health Sciences Faculty, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Kristie
authors.initials: K
authors.lastname: Bloom
authors.forename: Abdullah
authors.initials: A
authors.lastname: Ely
authors.forename: Claudio
authors.initials: C
authors.lastname: Mussolino
authors.forename: Toni
authors.initials: T
authors.lastname: Cathomen
authors.forename: Patrick
authors.initials: P
authors.lastname: Arbuthnot
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004261:DNA Replication; D004270:DNA, Circular / Q000235:genetics*; D004279:DNA, Viral / Q000235:genetics*; D003851:Deoxyribonucleases / Q000235:genetics* / Q000502:physiology*; D004195:Disease Models, Animal; D015316:Genetic Therapy; D005822:Genetic Vectors; D056945:Hep G2 Cells; D006509:Hepatitis B / Q000473:pathology / Q000628:therapy; D006515:Hepatitis B virus / Q000235:genetics* / Q000502:physiology*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016296:Mutagenesis; D015202:Protein Engineering; D014162:Transfection; D014779:Virus Replication
chemical_list: D004270:DNA, Circular; D004279:DNA, Viral; D003851:Deoxyribonucleases