Synthesis of Gal?(1,3)Gal?(1,4)GlcNAc?-, Gal?(1,4)GlcNAc?- 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 Gal?(1,3)Gal?(1,4)GlcNAc?, is expressed on glycosylphosphatidylinositol-anchored mucins of the infective trypomastigote stage of T. cruzi and triggers high levels of protective anti-?-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 Gal?(1,3)Gal?(1,4)GlcNAc?-BSA is recognized by purified anti-?-Gal Abs from chronic ChD patients ?230-fold more strongly than by anti-?-Gal Abs from sera of healthy individuals (NHS anti-?-Gal). Similarly, the pooled sera of chronic Chagas disease patients (ChHSP) recognized Gal?(1,3)Gal?(1,4)GlcNAc? ?20-fold more strongly than pooled NHS. In contrast, the underlying disaccharide Gal?(1,4)GlcNAc? and the monosaccharide GlcNAc? or GlcNAc? conjugated to BSA are poorly or not recognized by purified anti-?-Gal Abs or sera from Chagasic patients or healthy individuals. Our results highlight the importance of the terminal Gal? moiety for recognition by Ch anti-?-Gal Abs and the lack of Abs against nonself Gal?(1,4)GlcNAc? and GlcNAc? glycotopes. The substantial difference in binding of Ch vs. NHS anti-?-Gal Abs to Gal?(1,3)Gal?(1,4)GlcNAc?-BSA suggests that this neoglycoprotein (NGP) might be suitable for experimental vaccination. To this end, the Gal?(1,3)Gal?(1,4)GlcNAc?-BSA NGP was then used to immunize ?1,3-galactosyltransferase-knockout mice, which produced antibody titers 40-fold higher as compared with pre-immunization titers. Taken together, our results indicate that the synthetic Gal?(1,3)Gal?(1,4)GlcNAc? glycotope coupled to a carrier protein could be a potential diagnostic and vaccine candidate for ChD.

SUBMITTER: Schocker NS 

PROVIDER: S-EPMC4672149 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature