This report describes the design and construction of three between MCMV and MLP was HCMV which was able to recombinant adenoviruses of serotype 5 (Ad5) expressing induce significant amounts of elafin, particularly in human elafin (EL), also called elastase-specific inhibitor. Three A549 cells. When compared in vivo in rat lungs, results promoters were chosen to drive the synthesis of elafin: the were similar; MCMV was the only promoter which induced small (380 bp) human cytomegalovirus promoter (HCMV), significant amounts of elafin as assessed by Northern blot the Ad2 major late promoter (MLP) and the mouse cytoanalysis and ELISA, even with a low dose of virus megalovirus (MCMV) promoter. Human alveolar epithelial (3 x 10 8 p.f.u.). Our data indicate that the MCMV promoter cells (A549), as well as rat and human primary pulmonary is the promoter of choice for the strong induction of fibroblasts were infected with Ad5-HCMV-EL, Ad5-MLPadenovirus-mediated transgenes in the lung, and suggest EL, Ad5-MCMV-EL and with the control Ad5-dl70/3. The its suitability both in rodent experimental models and in MCMV promoter was the most efficient promoter in all cells humans for investigative and therapeutic purposes. studied. MLP was the least efficient promoter. Intermediate