To improve the gradual decrease in CFTR expression due to the transient episomal expression nature of AAV, and avoid the need for repeat dosing of the AAV vector, Cooney and colleagues designed a novel integrating AAV-based CFTR-expressing vector (termed piggyBac/AAV), which demonstrated efficient transduction and persistent expression in primary human CF airway cells in vitro and in mouse airways in vivo (Cooney et al., 2015). The gene discussed is CFTR; the disease is cystic fibrosis.