CFTR and cystic fibrosis: CF mice that lack the cystic fibrosis transmembrane conductance regulator (CFTR) protein (CFTR S489X-; FABP-hCFTR) were infected intratracheally with either 107, 106, or 105 Ax CFU and monitored daily for up to 4 d (96 h) for signs of distress and morbidity.