FIG. 1.

Analysis of immune sera in a competitive ELISA using PA83 as the competitor. Diluted rabbit anti-rPA serum (NR-3839) (▴), NHP anti-rPA serum (NR-9329) (•), and human anti-AVA serum (AVR801) (▪) were mixed with soluble PA83 at the indicated concentrations prior to addition to a PA83-coated ELISA plate and analyzed as described in Materials and Methods. Nonlinear-fit curves were generated for OD₄₀₅ readings, and readings were normalized to the OD upper asymptote as 100% as described in Materials and Methods. Rabbit and NHP curves were fit to a 4PL model, while the human serum curve was fit to a two-site competition model. Shown are graphs generated from duplicate plates with the mean ± standard error of the mean (SEM) shown for each point. The figure is representative of three independent experiments.