Zika virus is a single positive strand RNA virus with a genome that encodes three structural proteins and seven non-structural (NS) proteins: NS1, NS2A, NS2B, NS3, NS4A, NS4B and NS5. The flavivirus NS5 protein is the largest of the NS proteins and possesses enzymatic activities required for the synthesis of the 11 kb viral RNA genome, making it essential for replication and a prime target for drug candidates.

Recombinant Zika virus NS5 protein has an N-terminal His-tag and is expressed in insect cells.