Non-invasive administration of AAV to target lung parenchymal cells and develop SARS-CoV-2-susceptible mice

Adeno-associated virus (AAV)-mediated gene delivery holds great promise for gene therapy. However, the non-invasive delivery of AAV for lung tissues has not been adequately es-tablished. Here, we revealed that the intratracheal adminis-tration of an appropriate amount of AAV2/8 predominantly targets lung tissue. AAV-mediated gene delivery that we used in this study induced the expression of the desired pro-tein in lung parenchymal cells, including alveolar type II cells. We harnessed the technique to develop severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-suscepti-ble mice. Three kinds of immune function-relevant gene knockout (KO) mice were transduced with AAV encoding human angiotensin-converting enzyme 2 (hACE2) and then injected with SARS-CoV-2. Among these mice, type I inter-feron receptor (IFNAR) KO mice showed increased viral titer in the lungs compared to that in the other KO mice. Moreover, nucleocapsid protein of SARS-CoV-2 and multi-ple lesions in the trachea and lung were observed in AAV-hACE2-transduced, SARS-CoV-2-infected IFNAR KO mice, indicating the involvement of type I interferon signaling in the protection of SARS-CoV-2. In this study, we demon-strate the ease and rapidness of the intratracheal administra-tion of AAV for targeting lung tissue in mice, and this can be used to study diverse pulmonary diseases.