FIG 2.

SBA and OPKA levels in serum correlate with reduced illness after Shigella infection. SBA and OPKA titers were measured in serum samples from U.S. adult volunteers immunized with Shigella vaccine EcSf2a-2 (n = 15) and nonvaccinated controls (n = 13) prior to challenge with virulent S. flexneri 2a. SBA and OPKA titers were compared with disease outcomes postchallenge: dysenteric stools (A and E), loose stools (B and F), stool volume (C and G), and temperature (D and H). Plots show Spearman's correlations (r value coefficient). For all analyses, a P value of ≤0.05 was considered significant.