The B6-hDPP4 (line 1) 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. Additionally, Cyagen Biosciences has developed B6-hDPP4(line 2) mice (Catalog ID: I001188) on the C57BL/6JCya background strain and BALB/c-hDPP4 (line 2) mice (Catalog ID: I001189) on the BALB/cAnCya background strain. These two models replace the mouse Dpp4 gene p.S29 to part of intron 2 with the Human DPP4 CDS (aa.29-766)-rBG pA expression cassette, meeting the experimental needs for different strain backgrounds.