FIG. 3.

Splenocyte gp120-specific proliferative responses and serum anti-gp120 antibody titers elicited by DNA vaccination with or without delayed plasmid IL-12 administration. (A) Groups of BALB/c mice were immunized with 50 μg of sham PMV plasmid, 50 μg of PMV-gp120 alone, or 50 μg of PMV-gp120 plus 200 μg of PMV-IL-12 on day (d.) 10 following vaccine administration. Spleen cells from individual mice were harvested on day 18 postimmunization for functional analysis. Total splenocytes or splenocytes depleted of CD4⁺ or CD8⁺ T cells were stimulated with the indicated concentrations of recombinant HIV-1 IIIB gp120 protein, and proliferation responses were measured by [³H]thymidine incorporation. Results are presented as the mean SI ± SEM of four mice per group. (B) Groups of BALB/c mice were immunized with 50 μg of sham PMV plasmid, 50 μg of PMV-gp120 alone, or 50 μg of PMV-gp120 plus 200 μg of PMV-IL-12 given on the indicated days. On day 28 postimmunization, serum was collected from individual mice and the titer of gp120-specific antibody was determined by ELISA. Data are presented as the geometric mean titer ± SEM of eight mice per group.