Deciphering minimal antigenic epitopes associated with Burkholderia pseudomallei and Burkholderia mallei lipopolysaccharide O-antigens

Marielle Tamigney Kenfack,Teerapat Nualnoi,Alba Silipo,Charles Gauthier,Jérôme Marrot,Narisara Chantratita,David P Aucoin,Teresa L Shaffer,Abba Ngassimou,Roberta Marchetti,Mary N Burtnick,Paul J Brett,Yves Blériot,Antonio Molinaro,Kitisak Sintiprungrat,Marcelina Mazur

doi:10.1038/s41467-017-00173-8

Abstract

Burkholderia pseudomallei (Bp) and Burkholderia mallei (Bm), the etiologic agents of melioidosis and glanders, respectively, cause severe disease in both humans and animals. Studies have highlighted the importance of Bp and Bm lipopolysaccharides (LPS) as vaccine candidates. Here we describe the synthesis of seven oligosaccharides as the minimal structures featuring all of the reported acetylation/methylation patterns associated with Bp and Bm LPS O-antigens (OAgs). Our approach is based on the conversion of an l-rhamnose into a 6-deoxy-l-talose residue at a late stage of the synthetic sequence. Using biochemical and biophysical methods, we demonstrate the binding of several Bp and Bm LPS-specific monoclonal antibodies with terminal OAg residues. Mice immunized with terminal disaccharide–CRM197 constructs produced high-titer antibody responses that crossreacted with Bm-like OAgs. Collectively, these studies serve as foundation for the development of novel therapeutics, diagnostics, and vaccine candidates to combat diseases caused by Bp and Bm.

Highlights

Burkholderia pseudomallei (Bp) and Burkholderia mallei (Bm), the etiologic agents of melioidosis and glanders, respectively, cause severe disease in both humans and animals
If the coupling proves unsuccessful with thioglycoside 14, the latter would be readily convertible into other donors, such as anomeric fluorides and imidates
In agreement with the results obtained by enzyme-linked immunosorbent assay (ELISA), the surface plasmon resonance (SPR)-binding results indicate that monoclonal antibodies (mAbs) 4C7 tightly interacts with the terminal methylated talose residue found at the non-reducing end of Bm-like LPS OAg

Summary

Introduction

Burkholderia pseudomallei (Bp) and Burkholderia mallei (Bm), the etiologic agents of melioidosis and glanders, respectively, cause severe disease in both humans and animals. Disaccharide 6, which presented the highest recognition toward mAb 4C7 in the ELISA assay, was evaluated by SPR as well as disaccharide 7, and trisaccharide 2, which features the major intrachain epitope of Bp/Bm OAg. oligosaccharides 2, 6, and 7 were biotinylated using NHS ester chemistry and the resulting constructs (BIO-2, BIO-6, and BIO-7, respectively, Fig. 6a) were immobilized on the surface of a streptavidin (SA)-coated sensor chip

Results

Conclusion