Measurement of AHR
Mice were anesthetized by intraperitoneal injection of xylazine (12 mg/kg) and pentobarbital (70 mg/kg) at 3, 7, and 10 days post-infection. After anesthetization, mice were cannulated and connected to an animal ventilator (flexiVent®, SCIREQ, Montreal, QC, Canada). The mice inhaled aerosolized phosphate-buffered saline or 3, 6, 12, 24, or 48 mg/mL methacholine in phosphate-buffered saline. We measured the following parameters: resistance of the respiratory system (Rrs) and tissue damping (G); Rrs and G reflect the resistance of the central and peripheral airways, respectively15,16. These parameters were measured at frequent intervals of 10–15 seconds 12 times following activation of the nebulizer.