<p> <strong>Supplementary Video 1. Formation of aggregates and upregulation of virulence genes.</strong> Representative confocal microscopy video of 3 biological replicates of HeLa cells infected with Lm<em>-</em>dsRed<em>-PactA-</em>GFP MOI=20 for 2 hours. Video show the formation of bacterial aggregates and upregulation of virulence gene expression as shown by increased GFP expression. Scale bar 5 μm. </p>