Inhibition of hepatitis C virus RNA replicons by peptide aptamers

Background/aims: Hepatitis C virus infection is a major worldwide health problem, causing chronic hepatitis, cirrhosis and primary liver cancer. In addition to its role in the viral polyprotein-processing, the viral NS3 serine protease has been implicated in interactions with various cell constituents resulting in phenotypic changes including malignant transformation. NS3 is currently regarded a prime target for anti-viral drugs thus specific inhibitors of its activities should be important. With the aim of inhibiting NS3 protease activity as a means to inhibit HCV replication we used a novel bacterial genetic screen to isolate NS3-inhibiting peptide aptamers. Methods: We have isolated and characterized seven NS3-inhibiting peptide aptamers. We investigated the phenotypic changes that SEAP-secreting subgenomic RNA replicons undergo upon intracellular expression of these peptide aptamers, assayed by real-time RT-PCR and inhibition of SEAP secretion by transfected replicon cells. Results and conclusions: The peptide aptamers inhibited NS3 protease activity in vitro with an IC₅₀ in the low micromolar range. Upon transfection, aptamers inhibited the replication of SEAP-secreting genotype 1b subgenomic RNA replicons. Aptamer-based intracellular immunization may emerge as a promising antiviral approach to interfere with the life cycle and pathogenicity of HCV.