title: Synthesis of Galα(1,3)Galβ(1,4)GlcNAcα-, Galβ(1,4)GlcNAcα- and GlcNAc-containing neoglycoproteins and their immunological evaluation in the context of Chagas disease.
abstract: The protozoan parasite, Trypanosoma cruzi, the etiologic agent of Chagas disease (ChD), has a cell surface covered by immunogenic glycoconjugates. One of the immunodominant glycotopes, the trisaccharide Galα(1,3)Galβ(1,4)GlcNAcα, is expressed on glycosylphosphatidylinositol-anchored mucins of the infective trypomastigote stage of T. cruzi and triggers high levels of protective anti-α-Gal antibodies (Abs) in infected individuals. Here, we have efficiently synthesized the mercaptopropyl glycoside of that glycotope and conjugated it to maleimide-derivatized bovine serum albumin (BSA). Chemiluminescent-enzyme-linked immunosorbent assay revealed that Galα(1,3)Galβ(1,4)GlcNAcα-BSA is recognized by purified anti-α-Gal Abs from chronic ChD patients ∼230-fold more strongly than by anti-α-Gal Abs from sera of healthy individuals (NHS anti-α-Gal). Similarly, the pooled sera of chronic Chagas disease patients (ChHSP) recognized Galα(1,3)Galβ(1,4)GlcNAcα ∼20-fold more strongly than pooled NHS. In contrast, the underlying disaccharide Galβ(1,4)GlcNAcα and the monosaccharide GlcNAcα or GlcNAcβ conjugated to BSA are poorly or not recognized by purified anti-α-Gal Abs or sera from Chagasic patients or healthy individuals. Our results highlight the importance of the terminal Galα moiety for recognition by Ch anti-α-Gal Abs and the lack of Abs against nonself Galβ(1,4)GlcNAcα and GlcNAcα glycotopes. The substantial difference in binding of Ch vs. NHS anti-α-Gal Abs to Galα(1,3)Galβ(1,4)GlcNAcα-BSA suggests that this neoglycoprotein (NGP) might be suitable for experimental vaccination. To this end, the Galα(1,3)Galβ(1,4)GlcNAcα-BSA NGP was then used to immunize α1,3-galactosyltransferase-knockout mice, which produced antibody titers 40-fold higher as compared with pre-immunization titers. Taken together, our results indicate that the synthetic Galα(1,3)Galβ(1,4)GlcNAcα glycotope coupled to a carrier protein could be a potential diagnostic and vaccine candidate for ChD.
authors.affiliation: Department of Chemistry.
authors.forename: Nathaniel S
authors.initials: NS
authors.lastname: Schocker
authors.affiliation: Department of Biological Sciences, Border Biomedical Research Center, University of Texas at El Paso, 500 W. University Ave., El Paso, TX 79968, USA.
authors.forename: Susana
authors.initials: S
authors.lastname: Portillo
authors.affiliation: Department of Biological Sciences, Border Biomedical Research Center, University of Texas at El Paso, 500 W. University Ave., El Paso, TX 79968, USA Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brazil.
authors.forename: Carlos R N
authors.initials: CR
authors.lastname: Brito
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brazil.
authors.forename: Alexandre F
authors.initials: AF
authors.lastname: Marques
authors.affiliation: Department of Biological Sciences, Border Biomedical Research Center, University of Texas at El Paso, 500 W. University Ave., El Paso, TX 79968, USA.
authors.forename: Igor C
authors.initials: IC
authors.lastname: Almeida
authors.affiliation: Department of Chemistry kmichael@utep.edu.
authors.forename: Katja
authors.initials: K
authors.lastname: Michael
mesh_terms: D000913:Antibodies, Protozoan / Q000276:immunology; D014355:Chagas Disease / Q000276:immunology*; D000939:Epitopes / Q000276:immunology; D006023:Glycoproteins / Q000276:immunology*; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000276:immunology; D015800:Protozoan Proteins / Q000276:immunology*; D016052:Protozoan Vaccines / Q000138:chemical synthesis / Q000276:immunology*; D014349:Trypanosoma cruzi / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D000939:Epitopes; D006023:Glycoproteins; D009844:Oligosaccharides; D015800:Protozoan Proteins; D016052:Protozoan Vaccines
keywords: Chagas disease; biomarkers; carbohydrates; immunization; neoglycoprotein