MMZ ablation of the OE or genetic loss of hACE2 in OE and neurons prevents brain infection and lethal SARS-CoV-2 infection.

(A) HE staining of the indicated mouse tissues was performed 24 hours after intraperitoneal injection of 100 mg/kg MMZ or vehicle control. Scale bars 100 μm for the OE, OB, and 50 μm for the lung. Representative of N = 3 per condition. (B, C) Weight loss and survival of hACE2fl/y mice treated with MMZ or vehicle prior to infection with 105 PFU of SARS-CoV-2 virus. Asterisks indicate significant differences in weight between vehicle and MMZ treated hACE2fl/y animals. N = 14 (Vehicle) and 15 (MMZ). (D, E) Immunohistochemistry of WT, vehicle-treated hACE2fl/y, and MMZ-treated hACE2fl/y mouse cerebral cortex and lung 5–6 days after infection with 105 PFU of SARS-CoV-2 virus using antibodies that recognize viral nucleocapsid, the neuronal marker NeuN, the glial cell marker GFAP, the alveolar type II cell marker DC-LAMP, the AT1 cell marker PDPN, and the nuclear stain DAPI. Arrows indicate nucleocapsid staining colocalized with NeuN+ neurons (brain) or PDPN+ AT1 cells (lung). Representative of N = 4 per condition. (F, G) Immunohistochemistry of WT and MMZ-treated hACE2fl/y mouse cerebral cortex and lung 14 days after infection with 105 PFU of SARS-CoV-2 virus was performed as described in D and E. Note: Day 5 hACE2fl/y samples (middle panel) were included on the same tissue slide as a positive control. Arrows indicate nucleocapsid staining colocalized with neurons and AT1 cells in vehicle-treated hACE2fl/y mice. Representative of N = 4 per condition. Scale bars D-G 50 μm. (H) The Foxg1Cre/+ allele drives Cre expression in the OE and neurons of the brain (shown in red). (I, J) Weight loss and survival of hACE2fl/y and Foxg1Cre/+; hACE2fl/y mice after infection with 105 viral titer per mouse. n = 4 and 3 mice, respectively. (K) Pulse oximetry measured in WT, hACE2fl/y, and Foxg1Cre/+; hACE2fl/y mice 5–6 and 12 days after exposure to SARS-CoV-2 virus, respectively. *p p p t test, one-way ANOVA with Holm–Sidak correction for multiple comparisons, or log-rank Mantel Cox test. Numerical data in corresponding S1 Metadata tab. hACE2, human ACE2; HE, hematoxylin–eosin; MMZ, methimazole; OB, olfactory bulb; OE, olfactory epithelium; PDPN, Podoplanin; PFU, plaque-forming unit; SARS-CoV-2, Severe Acute Respiratory Syndrome Coronavirus 2; WT, wild-type.