title: Identification and characterization of an excretory-secretory product from Giardia lamblia.
abstract: A 58 kDa excretory-secretory product (ESP) of Giardia lamblia has been characterized. The ESP was purified over 508-fold by a combination of ammonium sulphate precipitation and sequential chromatography on affinity matrix and a gel filtration column. The homogeneity of the purified protein was established by sodium dodecyl sulphate polyacrylamide gel electrophoresis (Mr, 58 kDa) and analytical isoelectrophoresis (pI 4.75). The purified protein was recognized by the pooled sera of G. lamblia-positive patients as well as an antiserum raised against crude Giardia extract, thus indicating it to be an immunodominant parasite product. The ESP was found to agglutinate rabbit erythrocytes. The haemagglutinating activity of this protein was inhibited strongly by thyroglobulin, fetuin, asialofetuin and monosialoganglioside but not by simple sugars. The purified protein was characterized immunochemically and was found to be heat stable as well as protease sensitive. Lectin-binding studies of the purified ESP and its sensitivity to periodic-acid silver staining as well as to metaperiodate treatment clearly indicated its glycoprotein nature. The major localization site of the ESP was found to be on the surface of the parasite as revealed by flow cytometric analysis. Further, this glycoprotein induced fluid accumulation in ligated rabbit ileal loops and revealed a positive skin permeability reaction in the rabbit.
authors.affiliation: Department of Experimental Medicine and Biotechnology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: H
authors.initials: H
authors.lastname: Kaur
authors.forename: S
authors.initials: S
authors.lastname: Ghosh
authors.forename: H
authors.initials: H
authors.lastname: Samra
authors.forename: V K
authors.initials: VK
authors.lastname: Vinayak
authors.forename: N K
authors.initials: NK
authors.lastname: Ganguly
mesh_terms: D000818:Animals; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D016829:Giardia lamblia / Q000276:immunology / Q000378:metabolism*; D005873:Giardiasis / Q000276:immunology / Q000469:parasitology*; D006384:Hemagglutination; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007120:Immunochemistry; D007525:Isoelectric Focusing; D008297:Male; D008565:Membrane Proteins / Q000032:analysis* / Q000302:isolation & purification / Q000378:metabolism; D008970:Molecular Weight; D015800:Protozoan Proteins / Q000032:analysis* / Q000302:isolation & purification / Q000378:metabolism; D011817:Rabbits
chemical_list: D008565:Membrane Proteins; D015800:Protozoan Proteins