MUC5AC and infection: In IAV-exposed tracheobronchial ALI tissues, we observed viral antigen presence within multiple cell types at 24 h post-infection (hpi), with basal cells (KRT5+) being the dominant infected cell type, followed by ciliated cells (α-tubulin+) and goblet cells (MUC5AC+) (Fig. 2a, Supplementary Fig. 1).