KRT18 and infection: To generate an alternative lethal infection model, we engineered the hACE2 gene into the golden Syrian hamster genome via piggyBac-mediated transgenesis, whereby the expression of hACE2 is under the control of the human keratin 18 (K18) promoter and other regulatory sequences that are critical for epithelial specificity and produced multiple independent transgenic hACE2-hamster lines (Figure 1).