Histological lesions and immunohistochemical detection of viral antigen in lungs, brain, and liver of chicken infected with A(H5N8) HPAI virus; viral antigen staining in red. Note: (a) erythrocytes in the parabronchial lumen and atria of the lung. Bar = 50 μm. (b) The same. Bar = 20 μm. (c) Viral antigen in the alveolar macrophages and alveolar cells. Bar = 20 μm. (d) Venous and capillary hyperemia of the brain. Bar = 100 μm. (e) Local area of brain infiltration. Bar = 20 μm. (f) Many AIV antigens are found in neurons (insert with magnification x1000) and glial cells. Bar = 20 μm. (g) The venous and capillary hyperemia in liver. Bar = 20 μm. (h) The dystrophic changes at a vast area of liver parenchyma; the predominance of active macrophages; and a large number of mast cells, basophils, and eosinophils. Bar = 100 μm. (i) Viral antigen in the Kupffer cell (insert with magnification x1000) and in hepatocytes (bar = 20 μm). Insert demonstrates viral antigen presence in hepatocyte. Magnification x1000. HE: hematoxylin-and-eosin staining; IHC: immunohistochemical staining.