Our study on ACE2 provides a systematic road map to redesigning an entry receptor as a therapeutic, and we believe the same strategy could be applied to other entry receptors such as DPP4 for treating MERS and aminopeptidase N (ANPEP) for treating upper respiratory tract infections by HCoV-229E (42, 51). The gene discussed is ANPEP; the disease is Recurrent upper respiratory tract infections.