Designing and Construction of a Multiepitope-Based DNA Vaccine to Induce Protective Immunity against Hepatitis C Virus

Background: Hypervariability of hepatitis C virus (HCV) proteins is an important obstacle to design an efficient vaccine for the infection. To construct a protective vaccine against HCV, a DNA vaccine containing conserved epitopes of the virus was designed. To enhance the induced immune responses, adjuvant activity of N-terminal domain of gp96 (NT(gp96)) was used. Materials and Methods: A multi-epitope (PT) DNA vaccine encoding four HCV immunodominant cytotoxic T lymphocyte epitopes (HLA-A2 and H2-D d ) from Core, E2, NS3 and NS5B antigens in addition to a T-helper CD4+ epitope from NS3 protein and a B-cell epitope from E2 protein was designed and constructed. Then, NT(gp96) was fused to the PT DNA (PT-NT(gp96)). The stimulated cellular and humoral immune responses of PT and PT-NT(gp96) were evaluated in mice model. Results: According to multicolor flow cytometry assay, the frequency of CD8+ T-cells producing IFNγ and TNFα in the splenocytes of immunized mice with PT-NT(gp96) (6.8%, 4%) was significantly higher than those of immunized with PT (0.9% , 0.8%), respectively. The same results have obtained in hepatic lymphocytes of the vaccinated mice. The level of IgG, IgG1 and IgG2a in the mice vaccinated with PT-NT (gp96) was significantly higher than the value obtained from the mice immunized with PT. Conclusion: The results showed that PT DNA vaccine induces immune responses in mice model. Fusion of NT (gp96) to PT DNA vaccine causes to enhance cellular and humoral immune responses against HCV compared to sole PT vaccine.