FIG 5.

FliD protein adheres to the Caco-2 cell surface. Cell monolayers were treated with the recombinant FliD protein, anti-FliD antibodies, and/or FITC-conjugated anti-mouse IgG (green). Actin and nuclear DNA were labeled with TRITC-phalloidin (red) and 6-diamino-2-phenylindole (blue), respectively. Cells not treated with anti-FliD antibodies (A) or FliD protein (C) showed no labeling. Note the presence of FliD in clusters (green) on the Caco-2 cell surface (arrows) (B). SEM of Caco-2 cells treated with purified FliD, anti-FliD serum, and protein A labeled with gold particles (10 nm). Note the aggregation of gold particles at the tips of microvilli (white arrows) only after the cells were treated with FliD and anti-FliD serum (D). Note the absence of labeling in cell monolayers treated only with FliD (E) or anti-FliD serum (F). DAPI, 4′,6-diamidino-2-phenylindole.