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Review
. 2008 Jan;25(1):72-86.
doi: 10.1007/s11095-007-9504-0. Epub 2007 Dec 12.

RNAi for treating hepatitis B viral infection

Yong Chen  1 , Guofeng Cheng, Ram I Mahato
Affiliations
Review

RNAi for treating hepatitis B viral infection

Yong Chen et al. Pharm Res. 2008 Jan.

Abstract

Chronic hepatitis B virus (HBV) infection is one of the leading causes of liver cirrhosis and hepatocellular carcinoma (HCC). Current treatment strategies of HBV infection including the use of interferon (IFN)-alpha and nucleotide analogues such as lamivudine and adefovir have met with only partial success. Therefore, it is necessary to develop more effective antiviral therapies that can clear HBV infection with fewer side effects. RNA interference (RNAi), by which a small interfering RNA (siRNA) induces the gene silence at a post-transcriptional level, has the potential of treating HBV infection. The successful use of chemically synthesized siRNA, endogenous expression of small hairpin RNA (shRNA) or microRNA (miRNA) to silence the target gene make this technology towards a potentially rational therapeutics for HBV infection. However, several challenges including poor siRNA stability, inefficient cellular uptake, widespread biodistribution and non-specific effects need to be overcome. In this review, we discuss several strategies for improving the anti-HBV therapeutic efficacy of siRNAs, while avoiding their off-target effects and immunostimulation. There is an in-depth discussion on the (1) mechanisms of RNAi, (2) methods for siRNA/shRNA production, (3) barriers to RNAi-based therapies, and (4) delivery strategies of siRNA for treating HBV infection.

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Figures

Fig. 1
Fig. 1
Diagrammatic representation of hepatitis B virion. This virion is of spherical shape with a diameter of 42 nm, and consists of an outer envelope and an icosahedral nucleocapsid core. The outer envelope contains embedded proteins known as hepatitis B surface antigens (HBsAg). The HBV DNA genome is double-stranded and contains a long and short segment which overlap approximately 240 nt to form an open circle. The longer strand is 3020–3320 nucleotides long, and the shorter is 1700–2800 nucleotides long. The virus can be divided into four major serotypes (adr, adw, ayr, ayw) based on antigenic epitopes present on HBsAg, and into eight genotypes (A-H) according to overall nucleotide sequence variation of the genome.
Fig. 2
Fig. 2
A schematic diagram depicting the location of siRNAs in association with viral open reading frames and viral mRNAs within the HBV genome. Downward red arrows indicate the location of RNAi target sites within the four HBV transcripts, the siRNA4 targets to the common HBV polyadenylation signal region. The 3.5 kb transcript is the pregnomic RNA that serves as the template for HBV DNA replication and encodes the viral core and polymerase protein. 2.4 kb and 2.1 kb mRNA encode the viral envelope proteins. 0.7 kb mRNA encodes the viral X protein.
Fig. 3
Fig. 3
Mechanism of RNA interference (RNAi). Only core components of the RISC Loading Complex (RLC) and RISC are depicted. RLC contains a Dcr-2/R2D2 heterodimer which binds the siRNA containing dinucleotide 3’-overhangs. Core RISC component Ago2 displaces Dcr-2/R2D2. This schematic depicts transfer of duplex siRNA to Ago2 with either concurrent or immediate Ago2-mediated cleavage of the passenger strand. ATP hydrolysis is required for RISC maturation and has been postulated to accelerate release of the cleaved passenger strands as it does for cleaved mRNA. Mature RISC guides strand of the siRNA, and cleave mRNA targets. The pink arrows represent the pathway for a shRNA (A). The green arrows represent the pathway for a long dsRNA (B). The yellow arrows represent the pathway for a siRNA (C).
Fig. 4
Fig. 4
Design of DNA oligonucleotides for cloning the shRNA in vector. The green arrow illustrates the sense strand of a siRNA; the red arrow illustrates the antisense strand of a siRNA.
Fig. 5
Fig. 5
Scheme for improving siRNA stability, cellular uptake and gene silencing. Important features of siRNA structures include two base pair overhangs, seed region and mRNA cleavage site. A siRNA duplex with phosphorothioate (P=S) and 2’-base sugar modification (purple circle) confer resistance against exonuclease and endonuclease in comparison with a naked siRNA duplex. Bioconjugation with cholesterol or carrier molecules carrying targeting ligands increases cellular uptake and site-specificity.
Fig. 6
Fig. 6
HBV-specific siRNAs and their in vitro potency. (A) Chemical modifications of HBV-specific siRNAs. (B) Activity of chemical modified siRNAs incorporated with stable nucleic acid lipid particles (SNALP) against HBV in cell culture system. Secreted HBsAg levels were assayed by ELISA from HepG2 cells transfected with HBV expression vector and subsequently treated with HBV263M-SNALP, HBV1583M-SNALP, HBV263invM-SNALP, or an HCV irrelevant control (HCVirrM) at final concentrations of 0.5 to 25 nM. HBsAg levels were assayed 3 days after transfection, and expressed as OD 450 nm. Reproduced with permission from Morrissey et al. (2004).
Fig. 7
Fig. 7
Long hairpin RNA (lhRNA) sequences and HBV target sites. (A) Schematic illustration of lhRNA comprising 62 bp in the stem. G:U pairings are shown as well as a sequence of 2 U residues that are derived from the transcription termination signal. The antisense strand is perfectly complementary to its HBV target. (B) Organization of the HBV genome showing open reading frames (ORFs) and sites within the target vector, which are complementary to antisense components of lhRNA. Four arrows indicate the HBV transcripts, which have common 3′-ends, and include the lhRNA targets. (C) Hepatocyte concentrations of HBV mRNA from the core and surface regions expressed as a ratio to amount of GAPDH mRNA in vivo. Total RNA was isolated from liver cells at day 5 after hydrodynamic injection and subjected to quantitative real-time PCR. (D) HBsAg secretion from Huh7 cells cotransfected with indicated hairpin RNA-encoding plasmids together with HBV target plasmid. (E) Serum HBsAg concentrations were determined at day 5 after hydrodynamic injection of mice with pCH-9/3091 HBV target and indicated hairpin encoding sequences. Reproduced with permission from Weinberg et al. (2007).
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References

    1. {'text': '', 'ref_index': 1, 'ids': [{'type': 'PubMed', 'value': '9392700', 'is_inner': True, 'url': 'https://pubmed.ncbi.nlm.nih.gov/9392700/'}]}
    2. W. M. Lee. Hepatitis B virus infection. N. Engl. J. Med.337(24):1733–1745 (1997). - PubMed
    1. {'text': '', 'ref_index': 1, 'ids': [{'type': 'PubMed', 'value': '7901639', 'is_inner': True, 'url': 'https://pubmed.ncbi.nlm.nih.gov/7901639/'}]}
    2. J. Y. Lau and T. L. Wright. Molecular virology and pathogenesis of hepatitis B. Lancet342(8883):1335–1340 (1993). - PubMed
    1. {'text': '', 'ref_index': 1, 'ids': [{'type': 'PubMed', 'value': '1651454', 'is_inner': True, 'url': 'https://pubmed.ncbi.nlm.nih.gov/1651454/'}]}
    2. J. R. Wands and H. E. Blum. Primary hepatocellular carcinoma. N. Engl. J. Med.325(10):729–731 (1991). - PubMed
    1. {'text': '', 'ref_index': 1, 'ids': [{'type': 'PubMed', 'value': '9352870', 'is_inner': True, 'url': 'https://pubmed.ncbi.nlm.nih.gov/9352870/'}]}
    2. D. T. Lau, et al. Long-term follow-up of patients with chronic hepatitis B treated with interferon alpha. Gastroenterology113(5):1660–1667 (1997). - PubMed
    1. {'text': '', 'ref_index': 1, 'ids': [{'type': 'PubMed', 'value': '9011789', 'is_inner': True, 'url': 'https://pubmed.ncbi.nlm.nih.gov/9011789/'}]}
    2. J. H. Hoofnagle and A. M. di Bisceglie. The treatment of chronic viral hepatitis. N. Engl. J. Med.336(5):347–356 (1997). - PubMed

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