Extended Data Figure 7: Influenza receptor distribution on pig and human soft palate.
From: The soft palate is an important site of adaptation for transmissible influenza viruses
a–c, g–i, Pig (a–c) and human (g–i) soft palate tissues were stained with plant lectins SNA and MALII which are commonly used as markers for α2,6 and α2,3 sialic acids, respectively. d-f, j-l, Sialidase-A-treated control was run for each sample to ensure specificity of plant lectins and are displayed. Expression of α2,6 sialic acids (SNA staining) is found on the ciliated respiratory epithelium and goblet cells of the nasopharyngeal surface and in the submucosal glands of both the pig and human soft palate. Expression of α2,3-linked sialic acids is low in the pig soft palate and found primarily in goblet cells and submucosal glands. In the human soft palate, MALII (α2,3-linked sialic acids) staining sensitive to sialidase A treatment is found in the goblet cells and respiratory epithelium of the nasopharyngeal surface and in the basal cells of the oral surface. MALII staining in the submucosal glands was not sensitive to sialidase A treatment. Scale bars, 100 μm.
