ACE2 and infection: The protective efficacy of a sub-set of antibodies (258/407; 63%) was tested in a mouse model of infection using K18-hACE2 transgenic mice expressing human ACE-2 under the control of the epithelial cell cytokeratin (K18) promoter, with weight loss and survival as a metric for morbidity and mortality, respectively (Figure 4; Table S1).