Lectin Histochemical Investigations of the Distal Gut of Chicks with Special Emphasis on the Follicle‐associated Epithelium

Abstract

Carbohydrates on epithelial cell surfaces play an important role as attachment sites for different microorganisms like bacteria, viruses and protozoa. To obtain more information about the distribution of carbohydrates on the luminal surface along the intestine, lectin histochemical studies on different gut segments of chicks of different age groups were carried out using a panel of 13 lectins with specificities for Man, Glc, Gal, GalNAc, GlcNAc or GlcNAc oligosaccharides and Sia. Furthermore, we tried to find out whether previously reported specificities of certain lectins for M cells (membranous or multifold cells) in the bursa of Fabricius (BF) can be observed also on M cells of the intestine. As a result we were able to demonstrate binding of all lectins employed in these studies in all investigated gut segments. In some cases, the application of the same lectin led to varying staining intensities of the same histological structures in different age-groups (e.g. staining of the brush border with WGA, LEA, MAA or Conarva) or different gut segments (e.g. staining of goblet cells with CMA II, LEA and MPA). Hence, terminal carbohydrate residues of glycoconjugates on the intestinal epithelium vary depending on age and organ site. As glycoconjugates can act as attachment sites for microorganisms, these differences in the distribution of sugar residues may be one explanation for the site-specificity of certain pathogens. Furthermore, the binding of lectins to the follicle-associated epithelium (FAE) of the BF differs from that to the FAE of the intestine again stressing the site specificity of lectin binding. Thus, up to now no universal M-cell marker along the chicken intestine exists.

Binding of Avian Coronavirus Spike Proteins to Host Factors Reflects Virus Tropism and Pathogenicity

“…In particular, all binding S1 proteins used ␣2,3-sialylated substrates, as evidenced by the fact that attachment could be inhibited by pretreating the slides with VCNA or by preincubating them with MAA lectins, which preferentially bind to ␣2,3-sialidated oligosaccharides. ␣2,3-Sialic acids are present in the chicken trachea (26,52), the lower respiratory tract (1), the intestine (52), and the kidney (this study); however, interpretation of lectin histochemistry data is difficult due to differences in the binding of MAA isoforms and lectins from differ-ent suppliers (49; our data). Thus, although lectin histochemistry is widely used to gain insight into virus-host interactions, it appears limited in determining fine glycan specificity.…”

Infection of the tracheal epithelium by infectious bronchitis virus is sialic acid dependent

“…Such differences may also contribute to a different course of infection. Expression of a2,3-linked sialic acid on epithelial cells in chickens has been analyzed for the trachea and the intestine [20,21]. As far as other target organs of IBVare concerned, e.g.…”

CD 57 expression on lymphocytes present in the caecum and caecal tonsils in broilers infected with Eimeria tenella

“…They are the most effective cells regard to antigen transport, and by pinocytosis and phagocytosis take up the antigens from the intestinal lumen and transfer them inside the follicles. There is a marked cooperation between the nodular units of the caecal tonsils (Pohlmeyer et al, 2005). In broilers the number of intraepithelial lymphocytes within the gut reaches its highest value at 6 weeks of age.…”