FIG. 2.

Effects of PDI inhibitors on HN protein activities. (A) Effects of overnight incubation in DTNB (7.5 mM), bacitracin (BACI) (7.5 mM), or anti-PDI antibody (6 μl/ml) on the attachment activity of cell surface HN protein were analyzed by binding of RBCs. Cells were incubated with RBCs for 30 min at 4°C, bound RBCs were lysed, and released hemoglobin was quantified as described in Materials and Methods. RBC binding to inhibitor-treated cells is expressed as percentages of the binding obtained using untreated cells (No Tt). The results are averages of three independent experiments, and the error bars indicate standard deviations. (B) Effects of overnight incubation in DTNB (7.5 mM), bacitracin (BACI) (7.5 mM), or anti-PDI antibody (6 μl/ml) on the neuraminidase activity of cell surface HN protein were analyzed as described in Materials and Methods. The results are expressed as percentages of values obtained for untreated cells (No Tt) and are averages of three independent experiments.