Figure 3

Viral antigen in rgHPAIV infected tissues. Influenzavirus A nucleoprotein antigen (brown) detected by immunohistochemistry in various tissues. Vascular endothelium of capillaries and larger blood vessels is the dominant cell type supporting viral antigen in all tissues (arrowheads). (A) Brain, showing antigen in capillary endothelium and also in a focus of neurons and astrocytes (*). (B) Spleen, showing antigen in endothelium of arterioles and also associated with non-lymphocytic cells of the splenic parenchyma. (C) Lung, showing antigen in vascular endothelium; the main antigen staining is in the rich capillary network of the interstitium. (D) Heart, showing antigen in endothelium and in cardiomyocytes, where it is seen as a brown hue within the muscle fibres (+). (E) Kidney: antigen is mainly in the interstitial capillaries, but also in occasional tubular epithelial cells (arrow). (F) Jejunum, where antigen is present in capillaries within the laminar propria.