Figure 8
Suitability of the silica/DODAB/antigen system to induce IgG response. Humoral immune response to albumin and 18 kDa-hsp presented to the immune system via different systems. In A, absorbance at 492 nm as function of time (in days) after immunizing mice (n = 8/group) with 0.2 ml of 5 mM Tris/HCl (pH 7.4) solution containing: 10 μg of BSA or 0.02 mg silica or silica/DODAB (0.02 mg silica/0.01 mM DODAB) or silica/DODAB/BSA (0.02 mg silica/0.01 mM DODAB/10 μg of BSA) or DODAB/BSA (0.02 mM DODAB/10 μg of BSA). Animals were immunized on the abdomen at day zero, at two separate sites and bled through the opthalmic plexus at days 24 and 36. IgG antibodies quantification was performed by ELISA. Serum dilution was 1:50. (*), significant at P ≤ 0.05. In B, absorbance at 405 nm as function of time (in days) after immunizing mice (n = 5/group) with: 0.3 mL of 5 mM Tris/HCl (pH 7.4) solution containing 15 μg of 18 kDa-hsp M. leprae, or 0.03 mg silica or silica/DODAB (0.03 mg silica/0.015 mM DODAB BF), or silica/DODAB/18 kDa-hsp M. leprae (0.03 mg silica/0.015 mM DODAB/15 μg of 18 kDa-hsp M. leprae), or Al(OH)3/18 kDa-hsp M. leprae (0.03 mg Al(OH)3/15 μg of 18 kDa-hsp M. leprae); or immunized with: 0.3 mL of 1 mM NaCl (pH 6.3) solution containing 15 μg of 18 kDa-hsp M. leprae/0.03 mM DODAB BF. Animals were immunized on the abdomen at two separate sites at day zero, and an identical booster dose was given on day 15. Animals were bled through the opthalmic plexus at days 14, 28 and 84. IgG antibodies quantification was performed by ELISA. Serum dilution was 1:2. Naïve mice were considered to be those injected with buffer solutions.