Figure 4

a, Quantitative measurement of MERS-CoV RNA in the lungs of MERS-CoV-inoculated common marmosets. Samples were divided into three categories (1.9 × 10⁵ ± 9.9 × 10⁴; 1.6 × 10⁶ ± 5.2 × 10⁵; 2.6 × 10⁶ ± 1.7 × 10⁶) based on the viral load (top). The relative expression levels of Smad7 (middle) and FGF2 (bottom) are indicated. All values were normalized to GAPDH. Statistical significance was evaluated by Student's t-tests and P values are indicated. Error bars represent the mean ± s.d. of three selected tissue samples. b, Co-immunohistochemical staining of MERS-CoV NP, caspase-3, Smad7 and FGF2 in kidneys of MERS-CoV-inoculated common marmosets. All co-immunohistochemical staining was performed on the same slide, except Smad7 and MERS-CoV NP, which were stained on separate slides, and the overlay view was generated using two neighbouring slides. The specificity of anti-MERS-CoV antibodies was confirmed by overnight pre-incubation with a fivefold more concentrated MERS-CoV NP peptide before their application to the kidney sections. The central image in the bottom panel represents the background signal detected after inoculation of rabbit secondary antibodies. Nuclei counterstained by DAPI are shown in blue. c, Haematoxylin and eosin staining of kidney sections of MERS-CoV-inoculated common marmosets. Interstitial infiltration was observed in the infected kidneys (arrow heads). Characteristic histological features of acute kidney injury, including flattened epithelial cells (arrows) and peritubular capillary congestion (white arrows), were detected in the kidney sections of MERS-CoV-inoculated common marmosets. Images shown in b and c are representatives of the four common marmosets' kidneys in which the MERS-CoV RNAs were detected (Supplementary Fig. 8a). D, dilated renal tubules; PC, protein cast.