Bacterial aggregation in mouse pneumonia requires the T3SS translocon but does not require T3SS effectors.

<p>BALB/c mice were injected intranasally with PAK, PAKΔ<i>STY</i>, or PAKΔ<i>popB</i> and lungs were isolated, sectioned, and stained at 3 hours post-infection. (A) Widefield epifluorescent imaging showed PAK (red) bound to lung epithelium (green). Representative image from 67 images is shown. Scale bar, 100 µm. (B) The amount of aggregation by PAK and T3SS mutants was quantified and plotted against bacterial density (n≥60 images for each strain). Linear regression lines were applied to each bacterial strain. (C) Comparisons of linear regression lines showed no differences in slope but significant differences in the intercept of PAKΔ<i>popB</i> compared to PAK or PAKΔ<i>STY</i>. Statistics in Supplemental Statistical Analysis (<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004479#ppat.1004479.s010" target="_blank">Text S1</a>).