Figure 1
Lesion and viral detection in immature and mature feathers of naturally H5N8-infected ducks and geese. Hematoxylin and Eosin (HE) and anti-nucleoprotein A Immunohistochemistry (IHC). (A) Lesion and viral detection in immature and mature feathers, duck infected with H5N8 clade 2.3.4.4b, HE. (A1) Immature feather with extensive acute necrosis of feather and follicular epidermis (arrow). The feather pulp is infiltrated by leukocytes, mainly lymphocytes and plasma cells (asterisk). (A2) Mature feather with calamus (thin arrow) within normal limits. (A3) Abundant viral antigen is present within necrotic debris and outer layers of feather and follicular epidermis. (A4) Viral antigen is present in association with follicular epidermis of mature feather, under the calamus (arrowhead). (B) Growing and differentiating feather epidermis, duck infected with H5N8 clade 2.3.4.4b. (B1) At early stage of differentiation, feather epidermis is stratified. Necrosis is visible at the outer (corneal) layer (arrow) with viral antigen colocalization. (B2) At the stage of early differentiation, necrosis and single-cell necrosis/apoptosis can be seen within marginal plates and barb ridges (arrowhead) and with viral antigen colocalization. (B3) At the stage of cornication, keratinized barbs and barbules are disrupted and intermixed with necrotic cells and debris (asterisk) with viral antigen colocalization.
