Daclatasvir and NS5A protein complex. Computer illustration showing the structure of a molecule of the hepatitis C drug daclatasvir (ball and stick model, bottom) in complex with an NS5A dimer (ribbons). Daclatasvir inhibits nonstructural protein 5A (NS5A), which is found in the membrane of the hepatitis C virus (HCV) and plays a key role in the replication of the virus, producing RNA from DNA (deoxyribonucleic acid). Recent research suggests that daclatasvir targets two steps of the viral replication process, enabling rapid decline of HCV RNA.