Proteolytic processing, deubiquitinase and interferon antagonist activities of Middle East respiratory syndrome coronavirus papain-like protease Xingxing Yang,1,23 Xiaojuan Chen,13 Guangxing Bian,3 Jian Tu,4 Yaling Xing,1 Yayun Wang1 and Zhongbin Chen1,2 Correspondence Zhongbin Chen