Figure 5.

Representative photomicrographs of histopathology examination and immunohistochemical staining of necropsied lung tissues of MERS-CoV-infected common marmosets. Severe acute bronchointerstitial pneumonia centered on terminal bronchioles, with thickened alveolar interstitium and alveoli being filled with large amount of inflammatory cell infiltrate, edema, and hemorrhage in hematoxylin and eosin (H&E)–stained necropsied lung tissue of untreated (A) and MMF-treated (C) animals collected at 36 hpi (magnification, 100×). Abundant expression of MERS-CoV nucleocapsid protein was detected by mouse anti-MERS-CoV nucleocapsid protein (1:200) antibody (green) overlaid with counterstaining by propidium iodide (red) in the necropsied lung tissues of the untreated (B) and MMF-treated (D) animals (magnification, 100×). These pathological changes were seen extensively in multiple lobes of the necropsied lungs of the untreated and MMF-treated animals. Mild acute bronchointerstitial pneumonia with small amount of inflammatory cell infiltrate and preserved histological architecture in H&E-stained necropsied lung tissue of lopinavir/ritonavir-treated (E) animals collected at 72 hpi (magnification, 100×). Mild to moderate acute bronchointerstitial pneumonia with moderate amount of inflammatory cell infiltrate and hemorrhage in H&E-stained necropsied lung tissue of interferon-β1b-treated (G) animals collected at 72 hpi (magnification, 100×). Small amount of MERS-CoV nucleocapsid protein expression was detected in the necropsied lung tissues of the lopinavir/ritonavir-treated (F) and interferon-β1b-treated (H) animals (magnification, 100×). These pathological changes were only seen in lesions which were confined to 1–2 lobes of the necropsied lungs of the lopinavir/ritonavir-treated and interferon-β1b-treated animals. H&E-stained necropsied lung tissue (I) (magnification, 100×) without MERS-CoV nucleocapsid protein expression (J) of an uninfected control animal. Abbreviations: hpi; hours postinoculation; MERS-CoV, Middle East respiratory syndrome coronavirus; MMF, mycophenolate mofetil.