NECTIN4 and infection: Here, we showed that, unlike MeV, which can infect ALI cultures from the basolateral side, CDV requires additional conditions to overcome the epithelial barrier of the airway epithelium, namely, (i) interruption of junctional complexes, which exposes nectin-4 and makes it accessible for infection by CDV during the paracellular route, (ii) immunocytes that carry CDV to facilitate cell-to-cell transmission; (and (iii) restricted interferon signaling that enhances virus release from the apical surface.