Figure 2.

Immunohistochemical staining for H5N1 viral antigens (nucleoprotein, haemagglutinin)

Positive signals seen with diaminobenzidine (brown; Zymed Laboratories, San Francisco, CA, USA) or 3-amino-9-ethylcarbazole (red-brown; Sigma, St Louis, MO, USA). Slides counterstained with haematoxylin. (A) Positive staining (with nucleoprotein antibody) in nuclei and cytoplasm of pneumocytes (arrows). (B) Positive signals (with nucleoprotein antibody) in nuclei of mononuclear cells (arrows) with morphological features of macrophages in core of chorionic villus. Immunostaining in adjacent sections indicate cells to be Hofbauer cells (webfigure 4). (C) Positive signals (with nucleoprotein antibody) in nuclei of epithelial cells of trachea (arrows). (D) Positive staining (with nucleoprotein antibody) in cytoplasm and nuclei of neurons (arrows) from hippocampus. (E) Positive staining (with haemagglutinin antibody) in mononuclear cell in lymph node (arrow). (F) Positive staining (with haemagglutin antibody) in cytoplasm of pneumocytes (arrows) in fetal lung tissue.