Targeting the lung epithelium after intravenous delivery by directed evolution on underexplored sites of AAV capsid

The lung has not received the same tailored engineering as other major targets of debilitating genetic disorders. Here we engineered the surface-exposed residues AA452-458 of AAV9 viral proteins at the three-fold axis of symmetry and employed a Cre-transgenic-based screening platform to identify AAV capsids targeted to the lung after intravenous delivery in mice. We found that one engineered variant, AAV9.452sub.LUNG1, displays dramatically improved transgene expression in lung tissue after systemic delivery in mice. This improved transduction extends to alveolar epithelial type II cells, expanding the toolbox for gene therapy research for diseases specific to the lung.