Liu et al. analyzed rhesus macaques and found ACE2 were also expressed in epithelial cells lining on minor salivary gland ducts,30 which could be found in sinonasal cavity, oral cavity, pharynx, larynx, trachea, and lungs, amounting to 800–1000 individuals in total and contributing nearly 1% of saliva a day.31 This group also set up animal models by inoculating functional pseudovirus intranasally, and found that ACE2+ epithelial cells of minor salivary gland ducts are targeted host cells as early as 48 h after infection.30 The gene discussed is ACE2; the disease is infection.