Inhibition of Autophagy Suppresses SARS-CoV-2 Replication and Ameliorates Pneumonia in hACE2 Transgenic Mice and Xenografted Human Lung Tissues

Autophagy is thought to be involved in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, how SARS-CoV-2 interferes with the autophagic pathway and whether autophagy contributes to virus infection in vivo is unclear. In this study, we identified SARS-CoV-2-triggered autophagy in animal models, including the long-tailed or crab-eating macaque (Macaw fascicularis), human angiotensin-converting enzyme 2 (hACE2) transgenic mice, and xenografted human lung tissues. In Vero E6 and Huh-7 cells, SARS-CoV-2 induces autophagosome formation, accompanied by consistent autophagic events, including inhibition of the Akt-mTOR pathway and activation of the ULK-1-Atg13 and VPS34-VPS15-Beclin1 complexes, but it blocks autophagosome-lysosome fusion. Modulation of autophagic elements, including the VPS34 complex and Atg14, but not AtgS, inhibits SARS-CoV-2 replication. Moreover, this study represents the first to demonstrate that the mouse bearing xenografted human lung tissue is a suitable model for SARS-CoV-2 infection and that autophagy inhibition suppresses SARS-CoV-2 replication and ameliorates virus-associated pneumonia in human lung tissues. We also observed a critical role of autophagy in SARS-CoV-2 infection in an hACE2 transgenic mouse model. This study, therefore, gives insights into the mechanisms by which SARS-CoV-2 manipulates autophagosome formation, and we suggest that autophagy-inhibiting agents might be useful as therapeutic agents against SARS-CoV-2 infection. IMPORTANCE Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a global pandemic with limited therapeutics. Insights into the virus-host interactions contribute substantially to the development of anti-SARS-CoV-2 therapeutics. The novelty of this study is the use of a new animal model: mice xenografted with human lung tissues. Using a combination of in vitro and in vivo studies, we have obtained experimental evidence that induction of autophagy contributes to SARS-CoV-2 infection and improves our understanding of potential therapeutic targets for SARS-CoV-2.