O-Antigen Extraction, Purification, and Chemical Conjugation to a Carrier Protein

A variety of bacterial infections have been tackled by glycoconjugates over the recent years, and more vaccines are either under development at preclinical level or in clinical trials. So far, licensed glycoconjugate vaccines have made use of capsular polysaccharides or derived fragments. Today, many glycoconjugates are making use of other classes of sugars, in particular, the O-antigen portion of lipopolysaccharide molecules. Here, we report a simplified method for O-antigen extraction and purification that avoids the step of lipopolysaccharide isolation. Also, a selective chemistry for terminal linkage of O-antigen chains to a carrier protein is described, together with analytical methods for intermediates and final conjugate characterization.