SFTPA2 and infection: Since the 6 h time point resulted in significant differences in AM gene expression and also based on previous findings (52, 71), we focused our subsequent study for the other SP-A variants i.e., SP-A1 (6A2, 6A4), SP-A2 (1A3) and KO on the 6 h time point in order to identify early-stage gene expression changes after infection.