Comparative Analysis of the Antiviral Effects Mediated by Type I and III Interferons in Hepatitis B Virus-Infected Hepatocytes.

BACKGROUND: Type III interferons (IFNs) (λ1-3) activate similar signaling cascades as type I IFNs (α and ß) via different receptors. Since IFN-α and lymphotoxin-ß activate cytosine deamination and subsequent purging of nuclear hepatitis B virus (HBV) DNA, we investigated whether IFN-ß and -λ may also induce these antiviral effects in differentiated HBV-infected hepatocytes. METHODS: After determining the biological activity of IFN-α2, -ß1, -λ1, and -λ2 in differentiated hepatocytes, their antiviral effects were analyzed in HBV-infected primary human hepatocytes and HepaRG cells. RESULTS: Type I and III IFNs reduced nuclear open-circle DNA and covalently closed circular DNA (cccDNA) levels in HBV-infected cells. IFN-ß and -λ were at least as efficient as IFN-α. Differential DNA-denaturing polymerase chain reaction and sequencing analysis revealed G-to-A sequence alterations of HBV cccDNA in IFN-α, -ß, and -λ-treated liver cells indicating deamination. All IFNs induced apolipoprotein B messenger RNA-editing enzyme-catalytic polypeptide-like (APOBEC) deaminases 3A and 3G within 24 hours of treatment, but IFN-ß and -λ induced longer-lasting expression of APOBEC deaminases in comparison to IFN-α. CONCLUSIONS: IFN-ß, IFN-λ1, and IFN-λ2 induce cccDNA deamination and degradation at least as efficiently as IFN-α, indicating that these antiviral cytokines are interesting candidates for the design of new therapeutic strategies aiming at cccDNA reduction and HBV cure.