Hepatitis C Virus (HCV) infects more than 184 million individuals globally. In Pakistan, over 6% of the population lives with chronic hepatitis C, resulting in a significant disease burden. Despite ongoing efforts, an effective HCV vaccine remains to be developed. Over the last decade, several direct-acting antiviral agents (DAAs) have been developed that can successfully cure the infectious disease. However, the rapid viral replication and error-prone nature of the viral polymerase results in the emergence of drug resistant variants – Increasing resistance against every DAA has been reported. Therefore, a continues effort to discover new antiviral agents is essential. 

The HCV RNA dependent RNA polymerase (NS5b) plays an essential role in the viral replication and thus potentiates for an important target for antiviral drug discovery. This study aimed to identify new inhibitors of HCV NS5b genotype 3a, particularly against drug-resistant variant. We used in silico screening and a high-throughput biochemical assay for identify potential inhibitors of NS5b, which then validated in cell-based HCV replication assay. Through this strategy, we have identified two compounds, IOWH-032 and UF-RS271, as inhibitors of HCV NS5b. These compounds show potential to serve as candidate for the development into treatment regimens against HCV infection. Notably, UF-RS271 displayed 2-fold greater potency against the drug-resistant variant in the biochemical assay. 

Moreover, to gain insights into the structural characteristics of HCV NS5b of genotype 3a, we employed cryo-electron microscopy (Cryo-EM), and obtained the structural geometry at resolution of 6 A.. Overall, this comprehensive study offers valuable insights into HCV treatment and drug resistance, contributing to the ongoing efforts to combat this persistent health issue. 

Publications: 

1. Qadir, A., Riaz, M., Saeed, M., & Shahzad-ul-Hussan, S. (2018). Potential targets for therapeutic intervention and structure based vaccine design against Zika virus. European Journal of Medicinal Chemistry, 156, 444-460.  

2. Shahid, M., Qadir, A., Yang, J., Ahmad, I., Zahid, H., Mirza, S., ... & Shahzad-ul-Hussan, S. (2020). An engineered microvirin variant with identical structural domains potently inhibits human immunodeficiency virus and hepatitis C virus cellular entry. Viruses, 12(2), 199.  

3. Qadir, A., RSZ Saleem, & Shahzad-ul-Hussan, S. Identification of a novel selenium-based compound which inhibits Hepatitis C Virus (HCV) NS5b and its drug resistant variant (Manuscript in preparation).