FIG 3.

TcdA and TcdB increase C. difficile spore interaction with IECs. Caco-2 cells were differentiated and TcdA and TcdB intoxicated for 8 h or incubated with DMEM without serum as control and then were washed with PBS and infected for 3 h (Undifferentiated cells) or 1 h (differentiated cells) at an MOI of 10 with C. difficile spores. Unbound spores were rinsed off. Nonpermeabilized cells were stained for adhered spores. (A) Representative epifluorescence microscopy images of TcdA- and TcdB-intoxicated cells, cells incubated with heat inactivated TcdA/TcdB (or DMEM as control) for 8 h, which were then washed and infected with C. difficile spores. (B and C) C. difficile spore adherence relative in undifferentiated (B) and differentiated (C) cells. In bars, each dot represents one independent well from 2 independent experiments. Per well, a total of 5 fields were analyzed. Error bars indicate the mean ± SEM. Statistical analysis was performed by unpaired t test. ns, P > 0.05. Bars, 10 μm.