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

Advances in adeno-associated virus (AAV) engineering have provided exciting new tools for research and potential solu-tions for gene therapy. However, the lung has not received the same tailored engineering as other major targets of debili-tating genetic disorders. To address this, here we engineered the surface-exposed residues AA452-458 of AAV9 capsid pro-teins 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. Using a custom image processing pipeline to quantify transgene expression across whole tissue images, we found that one engi-neered variant, AAV9.452sub.LUNG1, displays dramatically improved transgene expression in lung tissue after systemic de-livery 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.

Automated summary

Advances in AAV engineering have provided new tools for research and gene therapy. This study engineering the AAV9 capsid protein to target the lung in mice, resulting in improved transgene expression, including in alveolar epithelial type II cells.