The Middle East Respiratory Syndrome—How Worried Should We Be?

Perlman, Stanley

The number of MERS-CoV-infected individuals is low, the availability of clinical samples is limited, and no autopsies have been reported. It is therefore crucial to begin development of an animal model for MERS, but thus far, experimental infection has been reported only in rhesus macaques (18) . MERS-CoV-infected macaques develop a nonfatal mild pneumonia. The absence of severe respiratory disease and kidney disease in these nonhuman primates makes it imperative that additional animal models be developed. Thus far, there have been no reports of successful infection of mice or ferrets, but infection of these animals may be initiated or enhanced if the receptor for the virus, human DPP4, is expressed in lieu of the mouse protein. Notably, similar efforts to introduce the human receptor for SARS-CoV resulted in a transgenic mouse that developed an overwhelming neuronal infection (19, 20) . These mice were useful for studies of vaccines and antiviral therapies but not for studies of pathogenesis. As mice engineered to express human DPP4 are developed, it will be important to minimize the likelihood of brain infection by careful attention to tissue-specific expression.