Synthesis and Immunogenicity of a Methyl Rhamnan Pentasaccharide Conjugate from A-Band Polysaccharide.

was added to the World Health Organization's priority pathogen list for research and development of new antibiotics in 2017. Alongside the development of new antibiotics to fight antimicrobial-resistant , vaccines would be an appealing addition to the toolbox health professionals have against this bacteria, which causes life-threatening respiratory infections. Recently, the structure of a novel immunogenic terminal carbohydrate moiety on the cell surface of was elucidated, consisting of a 3--methyl (1→4)-α-d-rhamnan pentasaccharide. As isolating this oligosaccharide from in sufficient amounts for producing a conjugate vaccine is challenging, herein we describe the synthesis of 3-methyl d-rhamnose oligosaccharide. We also report the conjugation of the synthetic pentasaccharide to human serum albumin and its resulting immunogenicity.