immunogenic Diffi cult to produce in large lung cell types including progenitor cells in both Inherently replication defi cient quantities normal lungs and following naphthalene-induced AAV-5 and AAV-6 lung epithelial ALI [20] tropism [10, 11] Transduce nondividing cells Long-lived gene expression Used in clinical trials for CF [12, 13] Lentivirus vectors Transduce nondividing cells [25] Oncogenesis risk due to Lentiviral transfer of shRNA to silence CD36 gene (RNA genome)