MUC5AC and infection: As also shown in Figure 5a,b, the Bp-PT– mutant secreting the active CyaA toxin increased the amount of mucin accumulated in the tracheas to a similar extent as the infection by the parental Bp-WT strain, despite a reduced trachea colonization capacity (~9.6 × 104 vs. ~5.6 × 105 CFU on day 5 and ~4.1 × 102 vs. ~4.2 × 103 CFU on day 14; Figure 5c).