FIG 4.

Comparison of the immunogenicity of in vivo EP-assisted minicircle-gag, p2ΦC31-gag, and pVAX1-gag. Groups of 10 BALB/c mice were immunized with p2ΦC31-gag, minicircle-gag, or pVAX1-gag at the indicated doses two or three times at 3-week intervals i.m. with in vivo EP. The immunized mice were sacrificed at 5 weeks and 8 weeks after the prime administration. The humoral and cellular immune responses were evaluated by p24-specific ELISA (A), gag epitope peptide IFN-γ ELISPOT assays (B), and intracellular cytokine staining assays (C and D). P values of <0.05 were considered significant using one-way ANOVA followed by Tukey multiple-comparison tests.