KRT18 and infection: The mice with the high hACE2 expression level (Tg lines 1 and 2) succumbed from day 3 to 5 post-infection (p.i.), whereas in the Tg line 3 which showed a lower hACE2 expression died 5 to 7 days p.i. Viral replication was found in the lungs of both K18-hACE2 Tg and non-Tg mice; however, the viral titers were lower and clearance much faster in the non-Tg mice.