viruses Article Potent MERS-CoV Fusion Inhibitory Peptides Identified from HR2 Domain in Spike Protein of Bat Coronavirus HKU4 Shuai Xia 1 , Qiaoshuai Lan 1 , Jing Pu 1, Cong Wang 1, Zezhong Liu 1, Wei Xu 1, Qian Wang 1, Huan Liu 2,*, Shibo Jiang 1,3,* and Lu Lu 1,* 1 Key Laboratory of Medical Molecular Virology of MOE/MOH, School of Basic Medical Sciences and Shanghai Public Health Clinical Center, Fudan University, Shanghai 200032, China;