Middle East respiratory syndrome (MERS) is a highly lethal respiratory disease caused by a novel betacoronavirus (MERS coronavirus, MERS-CoV). Since its first emergence in 2012, multiple transmission events of MERS-CoV (dromedary to human and human to human) have been reported, indicating that MERS-CoV has the potential to cause widespread outbreak. However, the epidemiology of MERS as well as immune responses against the virus in animal models and patients are still not well understood, hindering the vaccine and therapeutic developments. In this review, we summarize recent genetic and epidemic findings of MERS-CoV and the progress in animal model development, immune response studies in both animals and humans. At last, we discussed the breakthrough on vaccine and therapeutic development which are important against potential future MERS outbreak.