In order to focus on the disease process in the lung and to minimize the risk of mice becoming moribund before the end of the 5 day infection cycle, a separate cohort of CFTR–/– and WT-mice were infected with mucoid serotype 3 strain CHB 1126, which produces 122% more capsule than WU2 (Table 1), but we used a lower infectious dose of 1x105. This evidence concerns the gene CFTR and infection.