DPP4 and infection: Given that DPP4 functions as the cell surface receptor facilitating MERS-CoV entry into cells [26], and considering that adaptive evolution of MERS-CoV is linked to its capacity for human infection [18,19], this study undertook sequencing and comparative analysis of DPP4 alleles from a cohort comprising 30 Egyptians, 36 Sudanese, and 34 Saudi Arabians.