Evaluating novel adjuvant systems for the induction of humeral and cellular immune responses in hepatitis C virus capsid protein immunization

As a worldwide problem, hepatitis C Virus (HCV) infection similar to HIV and vaccine studies on HCV is among the hottest research topics in the field. Such a vaccine should elicit strong humeral and cellular responses against HCV antigens (Ags). The major aim of the present study was to compare and optimize the responses against HCV core protein (HCVcp) immunization formulated in novel human compatible adjuvants. BALB/c mice were immunized by HCVcp, purified in native conditions and in different adjuvant formulation in separate following groups: Ag+CpG, Ag+M720 (Montanide ISA 720), Ag+F127 (Pluronic acid) and cocktails of Ag+F127+CpG and Ag+M720+CpG. ELISA-based assays were used to analyze IgG, cytokine and CTL responses. The M720 (+CpG) immunized mice developed the highest HCVcp-specific titrations of total IgG,IgG1, 2a, 2b, and that of IFN-γ and IL-4 cytokines. HCVcp-specific-CTLs against relevant MHC class I peptides were detected only for Ag+M720+CpG, Ag+M720, and Ag+CpG groups, could be blocked by antimouse-CD8 antibodies and were stable for one year post-immunization. The M720 formulation of HCVcp (with a synergistic effect by inclusion of CpG) induces equally strong Th1/Th2 responses and stable CTLs.