Potent Inhibition of Hepatitis E Virus Release by a Cyclic Peptide Inhibitor of the Interaction between Viral Open Reading Frame 3 Protein and Host Tumor Susceptibility Gene 101.

Hepatitis E virus (HEV) generally causes self-limiting acute viral hepatitis in normal individuals. It causes a more severe disease in immunocompromised persons and pregnant women. Due to the lack of an efficient cell culture system or animal model, the life cycle of the virus is understudied, few antiviral targets are known, and very few antiviral candidates against HEV infection have been identified. Inhibition of virus release is one possible antiviral development strategy, which limits the spread of the virus. Previous studies have demonstrated the essential role of the interaction between the PSAP motif of the viral open reading frame 3 protein (ORF3-PSAP) and the UEV domain of the host tumor susceptibility gene 101 (TSG101) protein (UEV-TSG101) in mediating the release of genotype 3 HEV. Cyclic peptide (CP) inhibitors of the interaction between the human immunodeficiency virus (HIV) gag-PTAP motif and UEV-TSG101 are known to block the release of HIV. Using a molecular dynamic simulation, we observed that both gag-PTAP and ORF3-PSAP motifs bind to the same site in UEV-TSG101 by hydrogen bonding. HIV-released inhibitory CPs also displayed binding to the same site in UEV-TSG101, indicating that they may compete with ORF3-PSAP or gag-PTAP for binding to UEV-TSG101. Two independent assays confirmed the ability of a cyclic peptide (CP11) to inhibit the ORF3-TSG101 interaction. CP11 treatment also reduced the release of both genotype 1 and genotype 3 HEV by approximately 90%, with a 50% inhibitory concentration (IC) of 2 μM. Thus, CP11 appears to be an attractive candidate for further validation of its anti-HEV properties. There is no specific therapy against hepatitis E virus (HEV)-induced hepatic and nonhepatic health problems. Prevention of the release of the progeny viruses from infected cells is an attractive strategy to limit the spread of the virus. Interactions between the viral open reading frame 3 and the host tumor susceptibility gene 101 proteins have been shown to be essential for the release of genotype 3 HEV from infected cells. In this study, we have identified a cyclic peptide inhibitor of the above-mentioned interaction and demonstrate the efficiency of the inhibitor in preventing virus release from infected cells. Thus, our findings uncover the possibility of developing a specific antiviral agent against HEV by blocking its release from infected cells.