FIG. 1.

Time course of PA-specific IgG antibodies. Individual serum samples (15 CBA/J mice/group/time point) were analyzed for PA-specific IgG antibodies by ELISA at 0, 2, 4, and 6 weeks postimmunization. rPA-specific IgG endpoint titers are similar at 4 and 6 weeks for both TCI and i.m. immunized mice. Bars represent arithmetic mean endpoint titers, and symbols represent endpoint titers of individual mice. The endpoint titer is defined as the highest dilution that yielded an optical density reading greater than or equal to twice the background value. The titers were calculated after subtracting the mean absorbance of triplicate wells lacking antigen from wells containing antigen.