Secretion of type III effectors is sufficient to create but not maintain YACs.

<p>(A) Peritoneal macrophages were infected with GFP-expressing wild-type (YPIII/pYV) or a type III translocation mutant (YPIII/pYV/Δ<i>yopB</i>) strain for 60 minutes prior to the addition of pHrodo and incubated for an additional 40 minutes of infection (= 100 mins total infection). See main text for explanation of the indicated arrows. (B) The percentage of the bacteria co-localizing with the pHrodo signal from 40 or 100 mins of infection are shown from counting >30 macrophages from a single representative experiment that was repeated multiple times. (C) Peritoneal macrophages were infected with the indicated strains for either 40 or 100 minutes and then stained with a membrane marker (CD11b) and analyzed by fluorescent microscopy. Individual bacteria were scored for being membrane bound or internalized by examining each individual Z-plane image and the percentage of internalized was plotted. The data shown is representative of multiple experiments done with similar results in which >40 macrophages in each experiment were analyzed. (D) Peritoneal macrophages were infected with the indicated strains for either 40 or 100 minutes. Prior to each sample point, gentamicin was added to some of the wells to kill extracellular (and/or surface-exposed) bacteria. The percentage of gentamicin sensitive bacteria was derived by comparing the number of colony forming units (CFU) recovered from three independent wells per condition. Shown is a representative data set of a single experiment repeated several times with similar outcomes. (* <i>P</i> < 0.05 using student <i>t</i>-test)