IFNAR1 and infection: One week later, mock transduced and hACE2 transduced mice received an intrapulmonary challenge with SARS-CoV-2 (105 CCID50 per mouse), and lungs were collected at 2, 4 and 6 days post infection for C57BL/6J and IFNAR-/- mice and day 2 for IL-28RA-/- mice (Fig 2A).