Fig. 1.

Induction of HCV-specific humoral response by protein immunization with CpG adjuvant or GpC control adjuvant. The effect of protein and adjuvant dose is evaluated as well as the inhibitory effect of E1E2 on response to HCV core protein. Twelve protein immunization regimes were applied to mice in twelve groups (n = 5). Protein immunization consisted of 10 µg each of HCV core, E1E2, NS3 and NS5b. Eight weeks after protein immunization, mice were bled and sera were kept at −70 °C before assay. Anti-HCV IgG was assayed by ELISA. The recombinant HCV core (A), E1E2 (B), NS3 (C) or NS5b (D) protein were coated at 3 µg/ml in 96-well plates. The tested sera were serially diluted and applied to the plates. ELISA assay for anti-HCV IgG was performed as described in detail in Section 2. Absorbance was read at 450 nm. The IgG titre was determined by end-point dilution. The results were expressed as geometric means (GM). Comparison of ELISA results between two groups was conducted by using Mann–Whitney U test. Significant P values between groups vaccinated with different regimes are indicated. *P < 0.05 vs. 40 µg prot + 50 µg CpG; **P < 0.01 vs. 40 µg prot + 50 µg CpG. Data not shown for groups immunized with 10 µg CpG and 50 µg CpG, respectively.