SFTPA2 and infection: Two general groups of hTG mice, SP-A1 (6A2, 6A4), SP-A2 (1A0, 1A3), and SP-A-KO male and female mice (~9–12 months aged) were studied: a) one group was infected with K. pneumoniae, and b) the other group was exposed to filtered air (FA) or ozone (O3) before infection.