Figure 4

Distribution of avian (SAα2,3) and human (SAα2,6) influenza receptors in the nasal mucosa, trachea and lung of tree shrews. Both avian influenza virus receptor SAα2,3 Gal binding with MAA II and human influenza virus receptor SA α2,6 Gal binding with SNA are shown in brown. Stained with SNA (A,D,G), MAA II (B,E,H). SNA and MAA II lectins on sections previously treated with neuraminidase, where no faint binding was detected (C,F,I). A–C, Nasal mucosa. (A) In the nasal mucosa, stained SNA were detected on squamous epithelial cells (⬆) and vascular endothelial cells (B) Only a few of MAA staining was visible on squamous epithelial cells. D–F, Trachea (D) SNA staining was visible on almost all epithelial cells (E) a few stains of SA α2,3 Gal were found (⬆). G–I, lung (G) In the lung, non-ciliated cuboidal epithelium of the terminal bronchioles mainly expressed SAα2,6 Gal (⬆). (H) In the lung, alveolar epithelial cells mainly expressed SA α2,3 Gal and alveolar macrophages also expressed SA α2,3 Gal (⬆). Magnification ×400.