The BALB/c-hDPP4 (line 2) mouse is a humanized model constructed by gene editing technology to replace a partial region of the mouse Dpp4 gene with the human DPP4 gene CDS sequence. This model can be used to study the infection mechanisms of viruses such as MERS-CoV and COVID-19, as well as to develop related virus vaccines. Additionally, this model can be utilized to develop DPP4 inhibitor therapies. Similar models include the B6-hDPP4(line 1) mouse (Catalog ID: I001187), constructed on the C57BL/6NCya background strain, which replaces the sequence encoding aa.29~aa.760 of the mouse Dpp4 gene with the human DPP4 gene CDS sequence (aa.29-766), and the B6-hDPP4 (line 2) mouse (Catalog ID: I001188), constructed on the C57BL/6JCya background strain. These models meet the experimental needs of different strain backgrounds.