Efficient Inhibition of Hepatitis B Virus ReplicationIn Vivo, Using Polyethylene Glycol-Modified Adenovirus Vectors

Abstract

Achieving safe delivery of anti-hepatitis B virus (HBV) RNA interference (RNAi) effectors is an important objective of this gene-silencing technology. Adenoviruses (Ads) have a natural tropism for the liver after systemic administration, and are useful for delivery of expressed anti-HBV RNAi sequences. However, a drawback of Ad vectors is diminished efficacy and toxicity that results from stimulation of innate and adaptive immunity. To attenuate these effects we used monomethoxy polyethylene glycol-succinimidyl propionate (mPEG-SPA) to modify first-generation vectors that express an anti-HBV RNAi effector. Efficient hepatocyte transduction and knockdown of HBV replication were achieved after intravenous administration of 5 x 10(9) PEGylated or native recombinant Ads to HBV transgenic mice. After the first injection, circulating HBV viral particle equivalents (VPEs) remained low for 3 weeks and began to increase after 5 weeks. A second dose of PEGylated anti-HBV Ad caused a less sustained decrease in circulating VPEs, but no silencing after a second dose was observed in animals treated with unmodified vector. Release of inflammatory cytokines, including monocyte chemoattractant protein-1 (MCP-1), interferon-gamma, interleukin-6, and tumor necrosis factor-alpha, was elevated in animals receiving unmodified vectors. However, only a modest increase in MCP-1 was observed in mice that received a second dose of PEG Ads. Also, polymer-conjugated vectors induced a weaker adaptive immune response and were less hepatotoxic than their unmodified counterparts. Collectively, these observations show that PEG modification of Ads expressing RNAi effectors improves their potential for therapeutic application against HBV infection.

Targeted DNA Mutagenesis for the Cure of Chronic Viral Infections

“…Upon intravenous delivery of a relatively moderate dose, Ad vectors can transduce 100% of hepatocytes with minimal toxicity (96). Consequently, Ad vectors have been used to deliver anti-HBV RNAi sequences to the livers of HBV transgenic mice with considerable success (40,147). AAV vectors are also able to efficiently transduce the liver after delivery of moderate vector doses that cause minimal toxicity (216).…”

Sustained inhibition of hepatitis B virus replication in vivo using RNAi-activating lentiviruses

“…Accomplishing stable delivery of expressed HBV gene silencers to hepatocytes with sustained, longterm expression of therapeutic effecters remains the greatest challenge impeding the clinical translation of RNAi-based anti-HBV gene therapy. Adenoviral [7][8][9] and adeno-associated viral (AAV) 10,11 vectors have been used to achieve efficient hepatic delivery and expression of RNAi effecters following systemic administration. However, complications of immunostimulation and expression that may not be sustained compromise the use of these vectors for HBV therapy.…”

Biodistribution of Small Interfering RNA at the Organ and Cellular Levels after Lipid Nanoparticle-mediated Delivery

“…) and viral vectors (Crowther et al 2008;Guibinga et al 2008;Manjunath et al 2009). Human clinical trials using synthetic siRNA started in 2004 (Soutschek et al 2004), and a list of ongoing clinical trials applying siRNA was summarized (Morin et al 2009).…”