Figure 4

The modA2 locked ON variant was more sensitive to killing by human neutrophils. NTHI were incubated with human neutrophils that had been activated by addition of PMA without (A) or with (B) cytochalasin D pretreatment. After 30 minutes, the relative percent survival was calculated by comparison of viable (CFU) modA2 locked ON to modA2 locked OFF. (A) modA2 locked ON had significantly reduced survival in the presence of activated neutrophils compared to modA2 locked OFF, ***P < 0.001, unpaired t-test. (B) When cytochalasin D was used to prevent phagocytosis modA2 locked ON still had significantly reduced survival compared to modA2 locked OFF, **P < 0.005, unpaired t-test. The modA2 ON status provided less resistance to killing by neutrophils compared to the modA2 OFF status.