PASylated interferon α efficiently suppresses hepatitis B virus and induces anti-HBs seroconversion in HBV-transgenic mice

Interferon α (IFNα) so far is the only therapeutic option for chronic hepatitis B virus (HBV) infection that can lead to virus clearance. Unfortunately, its application is limited by side effects and response rates are low. The aim of this study was to generate a novel long-acting IFNα with the help of PASylation technology that adds a polypeptide comprising Proline, Alanine and Serine (PAS) to increase plasma half-life. Following evaluation of four selected recombinant murine IFNα (mIFNα) subtypes in cell culture, the most active subtype, mIFNα11, was fused with a 600 amino acid PAS chain. The activity of PAS-mIFNα was assessed by interferon bioassay and further evaluated for induction of interferon-stimulated genes (ISG) and antiviral efficacy in cell culture as well as in HBV-transgenic mice. PAS-mIFNα induced expression of ISG comparable to unmodified mIFNα and, likewise, evoked dose-dependent reduction of HBV replication in vitro. In vivo, PAS-mIFNα led to pronounced suppression of HBV replication without detectable liver damage whereas conventional mIFNα treatment only had a modest antiviral effect. Importantly, all PAS-mIFNα treated mice showed an anti-HBs antibody response, lost HBsAg and achieved seroconversion after three weeks. PASylated IFNα showed a profoundly increased antiviral effect in vivo compared to the non-modified version without toxicity, providing proof-of-concept that an improved IFNα can achieve higher rates of HBV antiviral and immune control.