There are many viruses which may cause respiratory infections in the normal and immunocompromised host. This study looks at the cystic fibrosis patient to determine the incidence of respiratory viral disease in this group, and, more specifically, to examine CF patients undergoing or about to undergo gene therapy to determine if there are respiratory viruses present which might interfere with using a replication-deficient adenovirus vector as the gene therapy modality. Bronchial lavages and brushings and nasal brushings will be collected and cultured by the shell vial assay for the detection of herpes simplex virus, cytomegalovirus, varicella-zoster virus, respiratory syncytial virus, influenza virus, parainfluenza virus, and adenovirus.