FIG. 2.

ScpC is responsible for IL-8 degradation. (A) IL-8 levels in supernatants of FaDu cells after infection with the S291 and the ScpC mutant (MOI of 50) for 1 h and 6 h as detected by ELISA. Two independent experiments were performed in duplicate. Data are expressed as means ± standard deviations of one representative experiment. (B) IL-8 detection by immunofluorescence after 6 h in uninfected cells (UN) or cells infected with S291 or the ScpC mutant (MOI of 50). The cells were fixed, blocked, and incubated for 1 h with a phycoerythrin-conjugated IL-8 monoclonal antibody (20 μg/ml; BD Biosciences) on ice. The bar represents 20 μM. (C) Western blot analysis of IL-8 cleavage. Bacterial suspensions (S291 or the ScpC mutant) were incubated with recombinant IL-8 (250 ng) for 6 h at 37°C. Samples were analyzed by Western blotting using a polyclonal goat anti-IL-8 antibody.