Enhanced Immune Responses of a Hepatitis C Virus core DNA Vaccine by co-Inoculating Interleukin-12 Expressing Vector in Mice

Hepatitis C (HCV) is a worldwide problem without an effective vaccine with more than 170 million chronically infected people worldwide. DNA vaccines expressing antigenic portions of the virus with adjutants have recently been developed as a novel vaccination technology. In the present study, a DNA vaccine expressing HCV core protein was developed with IL12 as a genetic adjuvant and different aspects of cell immune responses due to this vaccine were evaluated in an animal model of the infection. HCV core gene was inserted into pcDNA3. 1(-) eukaryotic expression vector and the recombinant plasmid was transformed into DH5α competent cells and a large scale DNA vaccine was prepared. The expression of the vector was verified in CHO cell line. Female C57BL/6 mice were immunized 3 times with 90 ng doses of the DNA vaccine on days 0, 14 and 28. Two weeks after the last immunization, the immune responses against HCV core antigen were assessed by lymphocyte proliferation, CTL cytotoxicity and cytokines secretion assays. The results showed that the co-administration of IL12, as a genetic adjuvant, increased the ability of HCV core DNA vaccine to enhance cytolytic T lymphocyte activity, lymphocyte proliferation and shifting of the immune response toward a T helper (Th1) pattern and altogether improved the protective immunity. This study demonstrated that intramuscular injection of HCV core DNA vaccine with a genetic adjuvant induced significant cellular immune responses in C57BL/6 mice.