Fig. 2. S. typhimurium mediates microtubule remodelling. (A) HeLa cells were transfected with a vector expressing FcRIIA, exposed to IgG-opsonized latex beads, then fixed 10 hours later and immunolabelled for ß–tubulin. Arrow indicates position of a latex bead. Scale bar corresponds to 10 µm. (B) Bacterial protein synthesis was blocked by adding tetracycline (Tet) at 7 hours p.i. Cells were fixed at 12 hours p.i, and examined for tubulin distribution. Results in left panel show the means ± s.d. of three independent experiments in which at least 70 S. typhimurium microcolonies were examined. Confocal images in right panel show tubulin distribution (red) around an S. typhimurium microcolony (green) in untreated and tetracycline-treated HeLa cells. (C) Representative confocal micrographs showing tubulin distribution in cells infected with S. typhimurium mutant strains. HeLa cells were infected for 8 hours with a sifA mutant or 10 hours for SPI-2 (ssaV^–), SPI-1 (prgH^–) or SPI-1/SPI-2 (prgH^–, ssaV^–) null mutant strains (green in merged images). Tubulin distribution (red in merged images) was examined by confocal microscopy. More than 50 S. typhimurium microcolonies containing at least three bacteria were examined for each strain. Scale bar: 5 µm. Dotted lines indicate cell perimeters.