A patient diagnosed with chronic Hepatitis C virus (HCV) infection is being considered for antiviral therapy. Which of the following drug classes directly targets the HCV RNA-dependent RNA polymerase, inhibiting viral replication?

Explanation

Hepatitis C virus (HCV) is an RNA virus. Its replication relies on several non-structural (NS) proteins. NS5B is the HCV RNA-dependent RNA polymerase, which is crucial for replicating the viral RNA genome. NS5B polymerase inhibitors (e.g., sofosbuvir) directly target this enzyme, thereby blocking viral RNA synthesis. NS3/4A protease inhibitors (e.g., simeprevir, grazoprevir) inhibit the viral protease responsible for processing the viral polyprotein. NS5A replication complex inhibitors (e.g., ledipasvir, velpatasvir) target the NS5A protein, which is involved in viral RNA replication and assembly. NRTIs are primarily used in HIV and Hepatitis B treatment, targeting reverse transcriptase.