In an ahead-of-print article in Virology Journal , Cui and associates report the results of a study of the molecular evolution of DPP4, a cell-surface receptor, across the mammalian phylogeny. Their analyses showed that the dN/dS value on the bat lineage (0.96) was four times greater than the mammalian average leading to the conclusion that Middle East respiratory syndrome coronavirus (MERS-CoV) ultimately has a bat-origin.
From the article –
Our analysis therefore suggests that the evolutionary lineage leading to current MERS-CoV co-evolved with bat hosts for an extended time period, eventually jumping species boundaries to infect humans and perhaps through an intermediate host. As such, the emergence of MERS-CoV may parallel that of the related SARS-CoV. Although one bat species, Taphozous erforatus, in Saudi Arabia has been found to harbour a small RdRp (RNA-Dependent RNA Polymerase) fragment of MERS-CoV, a larger viral sampling of bats and other animals with close exposure to humans, including dromedary camels . . . are clearly needed to better understand the viral transmission route. . . .
While bats may ultimately be the host reservoir for this coronavirus, the distribution of human infections throughout the Arabian Peninsula, among individuals of both genders, and various ages and occupations, indicates that there is some other intermediate host infecting the index cases and other sporadic cases in the region. The sooner the intermediate host is identified, the more likely that these outbreaks of MERS-CoV can be contained.
 Adaptive evolution of bat dipeptidyl peptidase 4 (dpp4): implications for the origin and emergence of Middle East respiratory syndrome coronavirus