text: The NS5A protein plays an important role in viral RNA replication, viral assembly, and complex interactions with cellular functions. The protein has been implicated in the modulation of host defenses, apoptosis, the cell cycle, and stress-responsive pathways. However, its function and complete structure have yet to be elucidated.
  NS5A seems to be key in triggering the formation of the membranous web in the absence of other similar nonstructural proteins. Many proteins within the host cell can be affected by NS5A, e.g. phosphatidylinositol 4-kinase IIIα (PI4KIIIα), a kinase required for the replication of HCV. This kinase takes part in the biosynthesis of phosphatidylinositol 4-phosphate (PI4P) by interacting with NS5A, which stimulates its activity and appears to improve the integrity of the membranous web.
  Recently, the central role of NS5A in viral proliferation has made it the target for drug development. As a result, new antiviral agents have been introduced for the treatment of HCV.