KRT18 and COVID-19: K18-hACE2 transgenic mice, engineered to express the human version of the ACE2 receptor were previously shown to represent a valuable COVID-19 model, faithfully recapitulating the viral virulence and accordingly, broadly used for SARS-CoV-2 pathogenesis studies and anti-viral therapy efficacy assessment [27,36,37,38,39,40].