Specific Recognition of β-Galactofuranose-Containing Glycans of Synthetic Neoglycoproteins by Sera of Chronic Chagas Disease Patients.
Chagas disease (CD) can be accurately diagnosed by detecting in patients' blood using polymerase chain reaction (PCR). However, parasite-derived biomarkers are of great interest for the serological diagnosis and early evaluation of chemotherapeutic efficacy when PCR may fail, owing to a blood parasite load below the method's limit of detection. Previously, we focused on the detection of specific anti-α-galactopyranosyl (α-Gal) antibodies in chronic CD (CCD) patients elicited by α-Gal glycotopes copiously expressed on insect-derived and mammal-dwelling infective parasite stages. Nevertheless, these stages also abundantly express cell surface glycosylphosphatidylinositol (GPI)-anchored glycoproteins and glycoinositolphospholipids (GIPLs) bearing nonreducing terminal β-galactofuranosyl (β-Gal) residues, which are equally foreign to humans and, therefore, highly immunogenic. Here we report that CCD patients' sera react specifically with synthetic β-Gal-containing glycans. We took a reversed immunoglycomics approach that entailed: (a) Synthesis of GIPL-derived Galβ1,3Manα-(CH)SH (glycan ) and Galβ1,3Manα1,2-[Galβ1,3]Manα-(CH)SH (glycan ); and (b) preparation of neoglycoproteins and , and their evaluation in a chemiluminescent immunoassay. Receiver-operating characteristic analysis revealed that can distinguish CCD sera from sera of healthy individuals with 85.3% sensitivity and 100% specificity. This suggests that Galβ1,3Manα1,2-[Galβ1,3]Manα is an immunodominant glycotope and that could potentially be used as a novel CCD biomarker.