FIG 6.

Comparison of relative avidity indexes of anti-Pfs25 antibodies against recombinant alga-Pfs25 antigen from four vaccination groups. Avidity of the anti-Pfs25 IgG was measured by continued binding to alga-Pfs25 antigen in the presence of 8 M urea compared to no urea as a control. Serum samples from alga-Pfs25 antigens vaccinated in combination with AL007 (2 mg/ml alum), AL019 (0.5 mg/ml alum plus GLA), EM081 (squalene–oil-in-water emulsion), and EM082 (squalene–oil-in-water emulsion plus GLA). The avidity index was calculated as the ratio of average optical density at 450 nm (OD₄₅₀) for urea-treated samples to the average OD₄₅₀ for PBS-Tween 20-treated samples. Statistical analysis was carried out using Student's t test to compare various adjuvant groups, and the values mentioned for significant differences between groups (P value < 0.05) are marked with a horizontal line above them. Vaccination with EM082 (oil-in-water plus GLA) showed a significantly higher avidity index than vaccination with alum (AL007) and than vaccination with oil-in-water emulsion without GLA (EM081).