The pattern of expression of airway surface liquid (ASL) homeostasis-associated genes (CFTR, BPIFA1, MUC1, MUC5AC, MUC5B) in the PCLS varied greatly between the three strains, and only infection with strain T15 induced statistically significant changes in this group of genes (Figure S3B–D). This evidence concerns the gene MUC5AC and infection.