Histological immunohistochemical sections from H5N8 infected duck. a) Lung showing residence of viral expression in lining epithelium of air capillaries and in infiltrating inflammatory cells. b) Heart showing viral expression in cardiac myocytes. c) Large vessel showing expression of viral antigen in lining endothelium. d) Duodenum showing expression of viral antigen in epithelial lining crypts. e) Spleen showing residence of viral antigen in lymphocytes. f) Brain showing expression of viral antigen in neurons, Capillary endothelium and glia cells.