DNA immunization with fusion genes encoding different regions of hepatitis C virus E2 fused to the gene for hepatitis B surface antigen elicits immune responses to both HCV and HBV

Figure 2 Comparison of the expression and secretion level of fusion proteins in COS cells. pcDNA3SE2-A, pcDNA3SE2-B, pcDNA3SE2-C, pcDNA3SE2-D, pcDNA3SE2-E are the plasmids expressing HBsAg fused with different HCV E2 fragments. The HBsAg in the culture medium (gray) and cell lysates (black) was measured by a commercial ELISA kit (Sino-American Co., Shanghai, China). Results were presented as means of three independent experiments (see Materials and Methods). The amount of HBsAg expressed by pcDNA3SE2-D in cell lysates was arbitrarily taken as 1.0.