Fig 2.

Histopathology and immunohistochemical staining for avian influenza virus antigen in tissues of chickens infected with the Mexican H7N3 HPAI virus performed at 2 days postinoculation. Virus is stained red. (A) Nasal epithelium, showing severe necrotizing rhinitis with submucosal congestion and edema and glandular hyperplasia. (Inset) Demonstration of viral antigen in the epithelial cells and debris, vascular endothelial cells, and infiltrating mononuclear cells. (B) Trachea, showing congestion and lymphocyte, macrophage, and heterophil infiltration in the submucosa. (Inset) viral antigen staining present in the vascular endothelial cells (arrow) and infiltrating macrophages (inset). (C) Lung, showing severe lymphoplasmacytic interstitial pneumonia with necrosis (arrow). (Inset) Viral antigen staining in epithelium of air capillaries, mononuclear cells, and necrotic debris. (D) Cerebrum, showing mild neuronal necrosis and focal gliosis (arrow). (Inset) Viral antigen staining in neurons and necrotic debris. (E) Comb, showing severe congestion. (Inset) Viral antigen staining in vascular endothelial cells (arrow) and infiltrating mononuclear cells. (F) Eyelid, showing severe congestion. (Inset) Viral antigen staining in vascular endothelial cells (arrow) and infiltrating mononuclear cells. (G) Spleen, showing splenitis, moderate lymphocyte depletion, and cell death with heterophilic inflammation. (Inset) Viral antigen staining in mononuclear cells and necrotic debris. (H) Cecal tonsil, showing moderate lymphocyte depletion and cell death with heterophilic inflammation. (Inset) Viral antigen staining in mononuclear cells and necrotic debris. Magnifications, ×400.