Figure 1. HCV antigen plasmid constructs and expression in human muscle RD cells.(A) Schematic representing the HCV genome illustrating the non-structural (NS) genes used as antigens in experiments (white blocks). (B) Schematic representing the HCV antigenic plasmids. Plasmids were constructed using pVAX backbone (empty vector), with expression driven by the CMV promoter and N-terminal IgE leader sequence (ILS). Four plasmids used for immunizations contained synthetic human codon-optimized HCV genotype 1a/1b consensus antigens: NS3/4A, NS4B, NS5A, NS5B. Identical plasmids with an additional C-terminal hemagglutinin (HA) tag were used for simplified staining in expression experiments. (C) Expression of HCV antigens by immunofluorescence staining of RD cells. Cells were stained with an anti-HA mAB 24 h after transfection with HA-tagged constructs.