Direct-acting antivirals and viral RNA targeting for hepatitis B cure

Effect of Hepatocyte Targeting Nanopreparation Syringopicroside on Duck Hepatitis B Virus and Evaluation of Its Safety

Syringopicroside is a kind of iridoid monomer compound isolated from Syringa oblata exhibiting a potent effect against hepatitis B virus (HBV). The therapeutic effect and safety of syringopicroside-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (SYR-NP) were studied on the model of HBV-infected ducklings and on cultured HepG2.2.15 cells. HBV DNA in ducklings was assessed by fluorescence quantitative PCR. In HepG2.2.15 cells, the content of HBsAg and HBeAg were assayed. Acute toxicity of SYR-NP was studied in ICR mice in 12 h and 7 days after SYR-NP administration. The serum levels of HBV DNA in ducklings treated with SYR-NP in a high dose was significantly lower than in the control. In HepG2.2.15 cells treated with different doses of SYR-NP, the concentrations of HBsAg and HBeAg were significantly below the control. Acute toxicity test showed high safety of SYR-NP. Thus, SYR-NP can inhibit replication of HBV DNA and protect the liver tissue.

HBV-Integration Studies in the Clinic: Role in the Natural History of Infection

Hepatitis B virus (HBV) infection is a major global health problem causing acute and chronic liver disease that can lead to liver cirrhosis and hepatocellular carcinoma (HCC). HBV covalently closed circular DNA (cccDNA) is essential for viral replication and the establishment of a persistent infection. Integrated HBV DNA represents another stable form of viral DNA regularly observed in the livers of infected patients. HBV DNA integration into the host genome occurs early after HBV infection. It is a common occurrence during the HBV life cycle, and it has been detected in all the phases of chronic infection. HBV DNA integration has long been considered to be the main contributor to liver tumorigenesis. The recent development of highly sensitive detection methods and research models has led to the clarification of some molecular and pathogenic aspects of HBV integration. Though HBV integration does not lead to replication-competent transcripts, it can act as a stable source of viral RNA and proteins, which may contribute in determining HBV-specific T-cell exhaustion and favoring virus persistence. The relationship between HBV DNA integration and the immune response in the liver microenvironment might be closely related to the development and progression of HBV-related diseases. While many new antiviral agents aimed at cccDNA elimination or silencing have been developed, integrated HBV DNA remains a difficult therapeutic challenge.

Understanding the antiviral effects of RNAi-based therapy in HBeAg-positive chronic hepatitis B infection

The RNA interference (RNAi) drug ARC-520 was shown to be effective in reducing serum hepatitis B virus (HBV) DNA, hepatitis B e antigen (HBeAg) and hepatitis B surface antigen (HBsAg) in HBeAg-positive patients treated with a single dose of ARC-520 and daily nucleosidic analogue (entecavir). To provide insights into HBV dynamics under ARC-520 treatment and its efficacy in blocking HBV DNA, HBsAg, and HBeAg production we developed a multi-compartmental pharmacokinetic-pharamacodynamic model and calibrated it with frequent measured HBV kinetic data. We showed that the time-dependent single dose ARC-520 efficacies in blocking HBsAg and HBeAg are more than 96% effective around day 1, and slowly wane to 50% in 1-4 months. The combined single dose ARC-520 and entecavir effect on HBV DNA was constant over time, with efficacy of more than 99.8%. The observed continuous HBV DNA decline is entecavir mediated, the strong but transient HBsAg and HBeAg decays are ARC-520 mediated. The modeling framework may help assess ongoing RNAi drug development for hepatitis B virus infection.