Potential use of synthetic α-galactosyl-containing glycotopes of the parasite Trypanosoma cruzi as diagnostic antigens for Chagas disease

Abstract

A synthetic glycoarray containing non-reducing α-galactopyranosyl moieties related to mucin O-glycans of the parasite Trypanosoma cruzi was evaluated by a chemiluminescent enzyme-linked immunosorbent assay with sera from patients with chronic Chagas disease. Our data revealed the disaccharide Galα(1,3)Galβ as the immunodominant glycotope, which may eventually be employed as a diagnostic antigen for Chagas disease.

Enhancing glycan isomer separations with metal ions and positive and negative polarity ion mobility spectrometry-mass spectrometry analyses

“…Understanding these O -glycan structures is of importance for the identification of potential T. cruzi α-Gal-containing biomarkers for the diagnosis of Chagas disease, follow-up of chemotherapy, and the development of preventative and therapeutic vaccines for Chagas disease. The synthetic glycans analyzed were mercaptopropyl glycosides, where mercaptopropyl groups were installed to allow conjugation of these glycans to maleimide-activated bovine serum albumin needed for the generation of a glycan array [36, 37]. …”

“…The O -glycans α- d -Gal-(1 → 3)-β- d -Gal-(1 → 4)-β- d -Glc-(CH 2 ) 3 SH (1)[36], α- d -Gal-(1 → 6)-[α- d -Gal-(1 → 2)]-β- d -Gal-(CH 2 ) 3 SH (2) [36], α- d -Gal-(1 → 3)-[α- d -Gal-(1 → 2)]-β- d -Gal-(CH 2 ) 3 SH (3) [Schocker, N.S., Almeida, I.C., Michael, K., unpublished data], β- d -Gal f -(1 → 4)- [β- d -Gal-(1 →6)]-α- d -GlcNAc-(CH 2 ) 3 SH (4) [Schocker, N.S., 2016, Ph.D. Dissertation, University of Texas at El Paso], α- d -Gal-(1 → 3)-β- d -Gal-(1 → 4)-α- d -GlcNAc-(CH 2 ) 3 SH (5)[37], α- l -Rha-(1 → 2)-α- l -Fuc-(CH 2 ) 3 SH (6), and α- l -Rha-(1 → 3)-α- l -Fuc-(CH 2 ) 3 SH (7) [Khamsi, J., Michael, K., unpublished data] were synthesized in the Michael lab. The glycans were dissolved in a MeOH/H 2 O/formic acid solution (49.45:49.45:0.1, v / v / v ) to a final concentration of ∼5 μM or lower.…”

“…Here we use an IMS-QTOF-MS platform to characterize standard glycans in both positive and negative polarities and also explore the effects of metal ions on enhancing glycan isomer separations. We next applied the optimized IMS-MS method to study synthetic α-Gal-containing O -glycans, some of which contain an immunodominant T. cruzi glycotope that is a potential biomarker for the diagnosis of Chagas disease [12, 36, 37]. …”

Development of Peptide-Based Lineage-Specific Serology for Chronic Chagas Disease: Geographical and Clinical Distribution of Epitope Recognition

“…One possibility is that the TSSA-I protein, if expressed at all in chagasic patients, is not sufficiently immunogenic to generate an antibody response, possibly due to post-translational glycosylation of the core peptide sequence. Identification of the disaccharide Galα(1,3)Galβ as the immunodominant glycotope present in the O-linked mucins, i.e., those glycosylated on serine or threonine residues of the peptide chain, has been reported recently [44], [45], and both serine and threonine are represented by one additional residue in TSSApep-I as compared with the TSSA-II epitope. However, equally likely, the TSSA I epitope may be conformational, with a structure that is not represented by the linear peptide.…”

Purification of Glycosylphosphatidylinositol-Anchored Mucins from Trypanosoma cruzi Trypomastigotes and Synthesis of α-Gal-Containing Neoglycoproteins: Application as Biomarkers for Reliable Diagnosis and Early Assessment of Chemotherapeutic Outcomes of Chagas Disease

“…In this chapter, we show two approaches toward the development of specific BMKs for the accurate diagnosis of ChD and early assessment of chemotherapeutic outcomes, based on a chemiluminescent enzyme-linked immunosorbent assay (CL-ELISA), using purified α-Gal-containing tGPI-mucins [25,27–29,24] or synthetic neoglycoproteins (NGPs) [30–32]. The NGPs are based on terminal, nonreducing α-galactosyl (α-Gal) residues known to be expressed in linear and branched O -glycans of the tGPI-mucins [19] (Fig.…”