A quantitative image-based screen identified host factors that affect <i>L</i>. <i>monocytogenes</i> invasion and cell-to-cell spread.

<p><b>(A</b>) Illustration of hypothetical phenotypes that can be identified in the screen. (<b>B</b>) Quantitative comparison of measurements in images of infected cells may decipher specific phenotypes. Colors indicate the phenotypes represented in (A). (<b>C-F</b>) Rank-product plots for quantitative metrics of invasion and spread. Gray line represents the distribution of rank-product values for the siRNAs, ordered by value. Statistically significant hits that are increased (yellow dots) or decreased (blue dots), relative to the average rank-product, are indicated and their names are listed in the corresponding color. siRNAs for which representative images are shown in G-J are highlighted and colored by phenotype. (<b>G-J</b>) Sample images from the screen exhibiting distinct phenotypes. Bacteria are shown in black and HUVEC nuclei are shown in blue. Foci are outlined. Scale bars: 50μm. (<b>G</b>) siVASP appeared in the center of the distribution for most metrics, indicating no significant phenotype. (<b>H</b>) siRAC2 exhibited few foci of normal size, indicating an invasion-specific defect. (<b>I</b>) siITGB1 exhibited many foci, indicating enhanced invasion. (<b>J</b>) siACTR2 exhibited foci with many bacteria per cell, indicating a cell-to-cell spread defect.