Fig. 5.

Flagella-based motility is required for optimal invasion of epithelial cells. (a) Bacterial motility was assessed by fluorescence microscopy using S. Typhimurium constitutively expressing GFP. Shown are means±sd from three independent experiments. P<0.05, Student's t-test. (b) Comparison of the role of flagellar-based motility in invasion. HeLa cells were infected with aer-LL or μaer-ST S. Typhimurium either with (shaded bars) or without (filled bars) centrifugation. Intracellular bacteria (1 h p.i.) were enumerated by plating. Strains were WT S. Typhimurium (WT), fliC : : Tn10 fljB : : Mud-Cm mutant (fliC/fljB) and a ΔSPI1 : : kan mutant (SPI1). Means±sd from at least three independent experiments are shown. *P<0.05, Student's t-test (compared with WT without centrifugation).