Prior studies have demonstrated that Ad-mediated delivery of a functional viral entry receptor into mice, such as the human dipeptidyl peptidase 4 (hDPP4) receptor for Middle Eastern Respiratory Syndrome coronavirus (MERS-CoV), can render them permissive to infection with human viruses, which are otherwise unable to support viral entry using the murine receptor homolog [26, 34]. The gene discussed is DPP4; the disease is infection.