E. Coli-Epithelial Contact Is Key to Host Response Figure 1. Structure of pathogenic EPEC E69. WT strain (a); LPS rough (b) and smooth mutant strains (c); flagella mutants E69 DfliC (d) and fliC+ (e) as observed by negative staining TEM. Magnification range was between 8800- 66000x. [OMV - outer membrane vesicles; LPS - O-polysaccharide chains of LPS; * - fimbriae; + - flagella]. doi:10.1371/journal.pone.0027030.g001 no IL-8 protein was secreted into the apical compartment by control and E69 WT infected cells (Figure 3f). A modest amount of apical IL-8 secretion was seen with the flagella negative mutant. Minimal IL-8 was detected in the basolateral compartment of control cells. During infection with the WT strain, IL-8 secretion into the basolateral chamber was found to be below the levels Figure 2. Structure of pathogenic EAEC O42. WT strain (a) and O42 DfliC (b) mutant; O42 aggregative adherence fimbriae mutants O42 DAafB (c) and O42 DAAF/II (d) as observed by negative staining TEM. Magnification range was between 8800- 66000x. [OMV - outer membrane vesicles; LPS - O-polysaccharide chains of LPS; * - fimbriae; + - flagella; EPS - exopolysaccharide]. doi:10.1371/journal.pone.0027030.g002 PLoS ONE | www.plosone.org 4 October 2011 | Volume 6 | Issue 10 | e27030