FIG 1.

TNA titers of mice immunized with wild-type and six-Asp mutant rPA purified proteins without Alhydrogel adjuvant. Two groups of 20 mice each were immunized with either wild-type or six-Asp mutant rPA purified proteins without adjuvant (15 μg of rPA/mouse). At 28 days postimmunization, mice were bled, and serum samples were analyzed using the TNA assay. The graph shows TNA titers (expressed as ED₅₀s) for each mouse. The horizontal lines represent the medians for the groups. A nonparametric Mann-Whitney test was performed to calculate the statistical significance using GraphPad Prism software. The P value is indicated. The median titer value for the wild-type rPA group was 234 and that for the six-Asp mutant rPA was 39. This figure is a representative of three independent immunization studies.