Fig. 4.

Adhesion of E. coli AAEC185 expressing novel chaperone/usher systems or Psa to HEp-2 (a), THP-1 (b) and RAW264.7 macrophage (c) cells. Strains were cultured overnight at 28 °C on LB agar plates supplemented with 10 μg chloramphenicol ml⁻¹ and 100 μM IPTG. Bacteria were added to tissue culture cells at an m.o.i. of 1–3. Phagocytosis of THP-1 and RAW264.7 cells was inhibited with 5 μg cytochalasin-D ml⁻¹ prior to addition of E. coli. Adhesion was determined by comparing the number of cell-associated c.f.u. with the total number of c.f.u. in the whole tissue culture well. Values are the means±sd of three independent experiments with duplicate assays from each experiment. *P<0.05; **P<0.0005.