Figure 1.

The role of continuous IL-12 and LP in mediating long-term control of infection after primary immunization with LP plus rIL-12. BALB/c mice (n = 6–8 per group) were initially vaccinated in the footpad and were boosted 2 weeks later (primary immunization) with LACK DNA (100 μg), control DNA (100 μg), LP (50 μg) with IL-12 or control DNA (100 μg), or LP plus rIL-12 (1 μg). Mice were then challenged with 1 × 10⁵ L. major (WHOM/IR/-/173) metacyclic promastigotes in their hind footpads 2 weeks (A) or 12 weeks (B) later, and weekly foot pad measurements were recorded by using a metric caliper. In addition, some of the mice (n = 6–8 per group) that were initially vaccinated and boosted with LP plus rIL-12 (primary immunization) were given supplemental treatment every 2 weeks in the same foot pad with either LP (50 μg), rIL-12 (1 μg), or LP plus rIL-12 (1 μg) for a total of four supplemental treatments. Infectious challenge was done 12 weeks after the primary immunization (4 weeks after the last supplementary treatment). Weekly footpad measurements were recorded by using a metric caliper. These data are representative of three independent experiments.