Objective: To demonstrate the utility of DNA vaccines for the tailored methods, the efficacy of enhanced immune responses, and the types of increased immune responses.
Methods: Four recombinant plasmids constructed included the coding regions for the core protein (pC) and for the core, E1 and E2 together (pCE1E2), IL-12 p35 and p40. These plasmids were transfected into mammalian cells to test their protein expression and were injected into the quadriceps muscles of BALB/C mice for measurement of specific antibodies and cytotoxic T-lymphocyte (CTL) responses.
Results: All the recombinant plasmids were shown to express specific antigens stably in mammalian cells. Codelivery of pIL-12 expression cassettes with pC and pCE1E2 in mice resulted in the enhancement of Ag-dependent CTL responses and the reduction of specific Ab response. The CTL activity was: pC=18.65%±5.71%, pCE1E2=20.07%±11.11%, pC+pIL-12=60.11%±17.37%, pCE1E2+pIL-12=67.48%±15.57%, respectively. The average A values of anti-HCV were pC=0.415±0.127, pCE1E2=0.358±0.096, pC+pIL-12=0.210±0.086, pCE1E2+pIL-12=0.258±0.125.
Conclusion: Codelivery of pIL-12 with plasmid DNA can enhance the efficacy of immune responses and shift the type of immune responses.