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

Pseudomonas aeruginosa 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 P. aeruginosa, 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 P. aeruginosa was elucidated, consisting of a 3-O-methyl (1-*4)-alpha-D-rhamnan pentasaccharide. As isolating this oligosaccharide from P. aeruginosa in sufficient amounts for producing a conjugate vaccine is challenging, herein we describe the synthesis of 3-O-methyl Drhamnose oligosaccharide. We also report the conjugation of the synthetic pentasaccharide to human serum albumin and its resulting immunogenicity.