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Inhibition of replication of hepatitis B virus using transcriptional repressors that target the viral DNA.

ABSTRACT: BACKGROUND:Chronic infection with hepatitis B virus (HBV) is a serious global health problem. Persistence of the virus occurs as a result of stability of the replication intermediate comprising covalently closed circular DNA (cccDNA). Development of drugs that are capable of disabling this cccDNA is vital. METHODS:To investigate an epigenetic approach to inactivating viral DNA, we engineered transcriptional repressors that comprise an HBV DNA-binding domain of transcription activator like effectors (TALEs) and a fused Krüppel Associated Box (KRAB). These repressor TALEs (rTALEs) targeted the viral surface open reading frame and were placed under transcription control of constitutively active or liver-specific promoters. RESULTS:Evaluation in cultured cells and following hydrodynamic injection of mice revealed that the rTALEs significantly inhibited production of markers of HBV replication without evidence of hepatotoxicity. Increased methylation of HBV DNA at CpG island II showed that the rTALEs caused intended epigenetic modification. CONCLUSIONS:Epigenetic modification of HBV DNA is a new and effective means of inactivating the virus in vivo. The approach has therapeutic potential and avoids potentially problematic unintended mutagenesis of gene editing.

SUBMITTER: Bloom K

PROVIDER: S-EPMC6739920 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Inhibition of replication of hepatitis B virus using transcriptional repressors that target the viral DNA.

Bloom Kristie K Kaldine Haajira H Cathomen Toni T Mussolino Claudio C Ely Abdullah A Arbuthnot Patrick P

BMC infectious diseases 20190912 1

<h4>Background</h4>Chronic infection with hepatitis B virus (HBV) is a serious global health problem. Persistence of the virus occurs as a result of stability of the replication intermediate comprising covalently closed circular DNA (cccDNA). Development of drugs that are capable of disabling this cccDNA is vital.<h4>Methods</h4>To investigate an epigenetic approach to inactivating viral DNA, we engineered transcriptional repressors that comprise an HBV DNA-binding domain of transcription activa ...[more]

PMID: 31510934

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Project description:MicroRNAs (miRNAs) are a class of small, single-stranded, noncoding, functional RNAs. Hepatitis B virus (HBV) is an enveloped DNA virus with virions and subviral forms of particles that lack a core. It was not known whether HBV encodes miRNAs. Here, we identified an HBV-encoded miRNA (called HBV-miR-3) by deep sequencing and Northern blotting. HBV-miR-3 is located at nucleotides (nt) 373 to 393 of the HBV genome and was generated from 3.5-kb, 2.4-kb, and 2.1-kb HBV in a classic miRNA biogenesis (Drosha-Dicer-dependent) manner. HBV-miR-3 was highly expressed in hepatoma cell lines with an integrated HBV genome and HBV+ hepatoma tumors. In patients with HBV infection, HBV-miR-3 was released into the circulation by exosomes and HBV virions, and HBV-miR-3 expression had a positive correlation with HBV titers in the sera of patients in the acute phase of HBV infection. More interestingly, we found that HBV-miR-3 represses HBsAg, HBeAg, and replication of HBV. HBV-miR-3 targets the unique site of the HBV 3.5-kb transcript to specifically reduce HBc protein expression, levels of pregenomic RNA (pgRNA), and HBV replication intermediate (HBV-RI) generation but does not affect the HBV DNA polymerase level, thus suppressing HBV virion production (replication). This may explain the low levels of HBV virion generation with abundant subviral particles lacking core during HBV replication, which may contribute to the development of persistent infection in patients. Taken together, our findings shed light on novel mechanisms by which HBV-encoded miRNA controls the process of self-replication by regulating HBV transcript during infection.IMPORTANCE Hepatitis B is a liver infection caused by the hepatitis B virus (HBV) that can become a long-term, chronic infection and lead to cirrhosis or liver cancer. HBV is a small DNA virus that belongs to the hepadnavirus family, with virions and subviral forms of particles that lack a core. MicroRNA (miRNA), a small (?22-nt) noncoding RNA, was recently found to be an important regulator of gene expression. We found that HBV encodes miRNA (HBV-miR-3). More importantly, we revealed that HBV-miR-3 targets its transcripts to attenuate HBV replication. This may contribute to explaining how HBV infection leads to mild damage in liver cells and the subsequent establishment/maintenance of persistent infection. Our findings highlight a mechanism by which HBV-encoded miRNA controls the process of self-replication by regulating the virus itself during infection and might provide new biomarkers for diagnosis and treatment of hepatitis B.

Dataset Information

Inhibition of replication of hepatitis B virus using transcriptional repressors that target the viral DNA.

Publications

Inhibition of replication of hepatitis B virus using transcriptional repressors that target the viral DNA.

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