Patrick Arbuthnot
University of the Witwatersrand, South Africa
Title: Engineering sequence-specific transcriptional repressors to disable replication of hepatitis B virus
Biography
Biography: Patrick Arbuthnot
Abstract
Chronic infection with hepatitis B virus (HBV) remains and important global health problem. Carriers of the virus are at high risk for cirrhosis and liver cancer. Available treatment only has modest curative efficacy and improved therapy is a priority to prevent the life-threatening complications that accompany the infection. The viral replication intermediate comprising covalently closed circular DNA (cccDNA) exists as a stable minichromosome in infected hepatocytes. Licensed treatment has no effect on cccDNA and devising methods based on gene therapy to disable this replication intermediate has considerable potential. Previous work from our laboratory demonstrated effective inhibition of HBV replication and targeted disruption of cccDNA by Transcription Activator-Like Effector Nucleases (TALENs). Although this approach is promising, unintended mutagenesis may occur in chronic carriers as a result of TALEN activity at HBV sequences that are integrated into the host genome. To circumvent this problem, we have produced repressor TALEs (rTALEs) that were designed to induce transcriptional repression at essential HBV transcriptional regulatory elements: the basic core promoter/enhancer II and preS2 promoter sequences. KRAB-encoding sequences were fused to the N-terminal regions of TALEs contain sequence-specific DNA binding domains derived from the AvrBs4 N1 Xanthomas TALE. Each rTALE was expressed from the CMV promoter and engineered to interact with an HBV-specific 18 bp target. The repressors were incorporated into recombinant adeno-associated viral vectors which were used to deliver the antiviral