Although HFFs are permissive for adenovirus replication in tissue culture, we wished to confirm the sensitivity to IFN of E1B 55 kDa null-mutants in normal human bronchial/tracheal epithelial cells (NHBECs), which better represent the host cell type encountered by serotype C adenoviruses in their natural site of infection, the upper respiratory tract [87]. The gene discussed is IFNA1; the disease is infection.