Figure 2. Viral pneumonia in macaques infected with H5N1 highly pathogenic avian influenza virus.

One macaque, VN1 (A, D, G, J), was inoculated with VN3040. Two macaques, Ho2 (B, E, H, K) and Ho3 (C, F, I, L), were inoculated with HOK1. VN1 and Ho2 were autopsied 7 days after virus inoculation. The dead macaque Ho3 was autopsied 5 days after virus infection. (A–F) Lung tissue sections were stained with H & E. A–C: low magnification (bars: 200 µm), D–F: high magnification (bars: 50 µm). (G–I) Viral antigen was stained with FITC-conjugated anti-influenza A virus antibody (green) in combination with eFluor615-conjugated cytokeratin (red) and DAPI for staining of nuclei (blue). (J–L) The distribution of viral antigen in lungs stained with FITC-conjugated anti-influenza A virus antibody (bright green). The images were analyzed under a sobel edge detection filter.