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. 2004 Oct 11;101(42):15196–15200. doi: 10.1073/pnas.0405954101

Fig. 4.

Fig. 4.

Immunofluorescence examination of tissues from nonhuman primates infected with variola. (a) Staining for monocytes/macrophages (green) and viral antigen (red) indicated the presence of infected monocytes/macrophages (gold) in the lymphoid tissues (lymph node shown) and in circulation. (b) In addition to monocytes/macrophages, virus-infected endothelial cells (green) were readily observed. (c) Staining for monocytes/macrophages (green) and apoptosis (red) revealed the presence of numerous tingible body macrophages in lymphoid tissues. The majority of apoptotic cells were not monocytes/macrophages but instead were lymphocytes. A rare apoptotic monocyte/macrophage (arrow) is shown. (d) A monocyte/macrophage with a clearly stained nonapoptotic nucleus (blue) is shown engulfing two separate apototic bodies.