RAG1 and severe combined immunodeficiency: Using various strains of commercially available knockout mice, the investigators demonstrated that innate (Ad5-hDPP4-transduced IFNAR−/−, MAVS−/−, and MyD88−/− mice), antibody (Ad5-hDPP4-transduced recombination activating gene 1−/− (RAG1−/−) severe combined immunodeficiency (SCID) mice), and T-cell (Ad5-hDPP4-transduced T-cell receptor α−/− (TCRα−/−) mice) mediated responses are important for protection against MERS-CoV.