Naïve Atm-null mice have abnormal respiratory mechanics without lower inspiratory capacity. Naïve and HKx31-infected WT (black bars) and Atm-null (gray bars) mice were ventilated on a Flexivent small animal ventilator. Inspiratory capacity (IC), tissue damping (G), tissue elastance (H), static lung compliance (Cst), tissue hysteresivity (η), elastance (Ers), and area were analyzed on naïve mice and at 14 and 56 dpi. Values represent means ± standard error with individual values shown as dots. P values were determined by Student’s t test. *P ≤ 0.05, **P ≤ 0.01; n ≤ 3/time point/group. dpi, days postinfection; HKx31, Hong Kong/X31; WT, wildtype.