K18-hACE2 mice were pretreated intranasally with 400 μg of naked ASO4 or a control ASO (scrambled) daily for 4 d before infection with 2,500 plaque forming units (PFU) of ancestral SARS-CoV-2 and monitored for 14 d (Fig. 5D). Here, KRT18 is linked to infection.