Nonstructural protein 3 (NS3) has three enzymatic functions: serine
protease, NTPase, and RNA helicase. NS3, along with cofactor
nonstructural protein 2B, catalyzes its own autocleavage and
cleaves the viral polyprotein. NS3 also functions in viral genome
replication as an RNA helicase, unwinding dsRNA in the 3' to 5'
direction. Likely, NS3 is involved in viral assembly, potentially
interacting with other nonstructural proteins, such as
nonstructural protein 2A.