<div><p>(A) Schematic representation of an inhibition test used to analyze the antigenic properties of mutant M22 proteins expressed on the surface of <i>S. pyogenes.</i> The test was based on the binding of mouse anti–M22-N to pure M22 protein immobilized in microtiter wells. This binding was inhibited with whole S. pyogenes bacteria expressing mutant M22 proteins.</p><p>(B) Ability of S. pyogenes strains expressing the M22 mutants E24A and E31A to cause inhibition. The positive control expressed the wild-type M22 protein and the negative control lacked M protein. As compared to the positive control, 50% inhibition (dashed line) required ~30-fold more bacteria expressing either of the mutant proteins. Results based on three separate experiments with duplicate samples, presented as means ± SD.</p></div
