KRT18 and infection: To demonstrate the therapeutic activity of 17T2 mAb we used a similar experimental model of infection: K18-hACE2 mice were challenged with a BA.1.1 isolate and 24 h later, either the 17T2 mAb or an isotype control antibody (IgGb12) were administered intraperitoneally (30 mg/kg) (Fig. 3a).