FIGURE 4.

Role of PfbB in adherence to A549 cells, as evidenced by microscopic analysis. Cells grown on coverslips were incubated with S. pneumoniae strain DP1004 (A) and its isogenic ΔpfbB mutant strain FP228 (B). Bacteria were labeled green using mouse anti-pneumococcal antibodies followed by fluorescein isothiocyanate-goat anti-mouse IgG. A549 cells were labeled with TRITC-phalloidin for cytosolic F-actin staining and by 4′,6-diamidino-2-phenylindole for nuclear staining. C, adherence to A549 cells of strain DP1004 and its isogenic ΔpfbB mutant strain FP228, as determined by microscopic counts. Data show means ± S.D. of three independent experiments conducted in duplicate. Statistical analysis was performed using Student's t test.