Opisthorchis viverrini: ultrastructure and cytochemistry of the glycocalyx of the tegument

Abstract

The ultrastructure and cytochemistry of the glycocalyx of the tegument of Opisthorchis viverrini during maturation from newly excysted juvenile to adult stages were investigated using colloidal iron, ruthenium red and lectin stainings. The results showed that the glycocalyx was intensely stained by the first two dyes, thus indicating the presence of relatively high amounts of negative charges. However, the thickness and intensity of the staining decreased during the fluke's maturation. Binding studies using lectin probes on the surface of adult parasites showed that binding sites for Canavalia ensiformis (Con A), Triticum vulgaris (WGA) and Ricinus communis I (RCA I) were present in relative large amounts on the glycocalyx of the adult tegument, whereas those for Dolichos biflorus (DBA) were relatively fewer in number, and those for Ulex europaeus I (UEA I) were absent. The binding patterns of Con A, WGA, RCA I and DBA were generally similar, and the reaction product was uniformly distributed over the dorsal and ventral surfaces of the parasite's body. These bindings, therefore, indicate the presence of D-mannose/D-glucose, N-acetyl-Dglucosamine/sialic acid, D-galactose and N-acetyl-D-galactosamine residues on the glycocalyx of the adult tegument.

Effect of niclosamide on the tegumental surface of Haplorchis taichui using scanning electron microscopy

“…The dorsal surface showed a similar disruption to the ventral surface and the posterior region was more severely disrupted than the anterior part. The findings are similar to the effects of praziquantel (Apinhasmit & Sobhon, 1996), albendazole sulphoxide (Buchanan et al , 2003), and 5-chloro-2-methylthio-6-(1-naphthyloxy)-1-H-benzimidazole (Rivera et al , 2004, 2005). The regional differences in damage may be due to tegumental structure, route of drug uptake and drug metabolism (McKinstry et al , 2003).…”

“…membrane. Similar observations were made for other anthelmintic drugs (Lee et al, 1987;Stitt & Fairweather, 1993;Apinhasmit & Sobhon, 1996;Meaney et al, 2002Meaney et al, , 2003Buchanan et al, 2003). Blebbing and swelling are early changes leading to loss of the tegument.…”

Parasitic helminths: a pharmacopeia of anti-inflammatory molecules

“…The ligation of Siglec 8 on eosinophils (and Siglec 9 on neutrophils; von Gunten et al 2005) induces apoptosis (Nutku et al 2003), and the ability of helminths to trigger such a response would be to their benefit. The published literature on parasitic helminths possessing sialic acid-based glycoproteins is conflicting, with many studies suggesting that helminths do not synthesize them, and there is an equally convincing body of evidence demonstrating that sialic acid reactivity can be detected in worm extracts or ES products from many helminth species (McDiarmid and Podesta, 1984; Apinhasmit et al 2000; Elayoubi and Craig, 2004; Johnston, unpublished observations). We feel that this issue is deserving of clarity that will only come with additional well-controlled experimentation.…”

Stage-specific expression and antigenicity of glycoprotein glycans isolated from the human liver fluke, Opisthorchis viverrini

“…In O. viverrini infection, secreted and cell surface tegumental components of the parasite are detected along the host biliary epithelium and activate immune/inflammatory responses (Sripa et al, 2000). A few studies of O. viverrini glycoconjugates have been reported, but glycan characterization was limited to detection by antibody or lectin staining (Akai et al, 1992; Apinhasmit et al, 2000). To gain a better understanding of parasite biology and host-parasite interactions, the glycans found on O. viverrini glycoconjugates need greater characterization.…”