Kim et al. showed that histopathological features of pulmonary fibrosis were observed in MERS-CoV-infected hDPP4-transgenic (hDPP4-tg) mice, including alveolar septal thickening, inflammatory monocyte infiltration, macrophage polarization, acute pulmonary inflammatory response, as well as increased expression of pro-inflammatory factors and pro-fibrotic factors, such as TNF-α, IL-1β, TGF-β, type I collagen and type III collagen [63] (Table 2). This evidence concerns the gene TNF and pulmonary fibrosis.