The design and synthesis of an α-Gal trisaccharide epitope that provides a highly specific anti-Gal immune response

Abstract

Carbohydrate antigens displaying Galα(1,3)Gal epitopes are recognized by naturally occurring antibodies in humans. These anti-Gal antibodies comprise up to 1% of serum IgG and has been viewed as detrimental as they are responsible for hyperacute organ rejections. In order to model this condition, α(1,3)galactosyltransferase-knockout mice are innoculated agaisnt the Galα(1,3)Gal epitope. In our study, two α-Gal trisaccharide epitopes composed of either Galα(1,3)Galβ(1,4)GlcNAc or Galα(1,3)Galβ(1,4)Glc linked to a squaric acid ester moiety were examined for their ability to elicit immune response in KO mice. Both target epitopes were synthesized using a two-component enzymatic system using modified dissacharide substrates containing a linker moiety for coupling. While both glycoconjugate vaccines induced the required high anti-Gal IgG antibody titers, it was found that this response had exquisite specificity for the Galα(1,3)Galβ(1,4)GlcNAc hapten used, with little cross reactivity with the Galα(1,3)Galβ(1,4)Glc hapten. Our findings indicate that while homogenous glycoconjugate vaccines provide high IgG titers, the carrier and adjuvanting factors can deviate the specificty to an antigenic determinant outside the purview of interest.

Methyl β-lactoside [methyl β-D-galactopyranosyl-(1→4)-β-D-glucopyranoside] monohydrate: a solvomorphism study

“…The crude syrup was dissolved in anhydrous CH 2 Cl 2 (20 ml), CCl 3 CN (2.43 ml, 2.42 mmol) and DBU (200 ml, 1.34 mmol) were added, and the resulting mixture was stirred at 293 K for 2 h. The reaction mixture was then concentrated at 303 K in vacuo and purified by flash chromatography on a silica-gel column (12 Â 2.5 cm; eluted with ethyl acetate/hexanes, 2:1 v/v) to afford (V) in 76% yield in two steps (1.81 g, 2.32 mmol). 1 H and 13 C{ 1 H} NMR spectra obtained for (V) were consistent with those reported previously (Anraku et al, 2017).…”

A bioconjugate leveraging xenoreactive antibodies to alleviate cocaine-induced behavior

“…28 All vaccinated groups responded similarly to treatment with 3 (Table 1). It was also found that the non-prevaccinated group had a detectable, albeit low, titer for 1 , but there was no detectable affinity for 1 by SPR (Table 1).…”

“…25–27 Thus, the GAL hapten ( 1 ) was produced in high quantity using a two-component chemoenzymatic process resulting in the GAL trissacharide with an azide handle appended. 28,29 This substrate can then undergo reduction to the amine, followed by coupling to a squaric acid moiety to produce the GAL hapten 1 . Hapten 1 is coupled to a T-cell epitope carrier, 2 , via incubation in borate buffer to react with free lysine residues (Scheme 1).…”

Purification and Characterization of Antibodies Directed against the α-Gal Epitope

“…It is considered a hapten due to its small size and can only develop its immunogenic effect in combination with bigger antigens. Synthetic α-Gal haptens are currently designed and used in animal models to investigate different types of immune responses [20].…”