The host proteases such as furin (Millet and Whittaker, 2014), cathepsins (Bertram et al., 2013), human airway trypsin-like protease (Berman et al., 2000; Bertram et al., 2011), and transmembrane protease serine protease-2 (TMPRSS-2) (Gierer et al., 2013) are widely expressed in many important organs, which is a critical reason for the systematic infection, serious pathogenicity, and high mortality of the CoVs. This evidence concerns the gene TMPRSS2 and infection.