Abstract: The invention is based on the use of a basic reagent under basic conditions to separate conjugated saccharide from unconjugated components in a sample, e.g. a vaccine, by precipitation of the conjugated saccharide. The invention allows rapid and quantitative separation of conjugated and conjugated components, which may be exploited in analytical methods for quantifying unconjugated saccharide or carrier. Therefore, the separation of conjugated and unconjugated components using the invention may be advantageously combined with a quantitative saccharide or carrier analysis to provide improved quality control for conjugate vaccines.

Abstract: Capsular saccharides are typically anionic. In the invention, however, cationic groups are introduced, such that the modified saccharide has a repeating unit which includes both cationic and anionic groups. These cationic and anionic groups can be balanced to give a zwitterionic repeating unit. These modifications can convert a saccharide that is normally a T-independent antigen into one that can activate T cells without requiring conjugation to a carrier. Typically, the invention modifies an anionic bacterial capsular saccharide antigen by converting a neutral group in the saccharide into a cationic group e.g. to change —NHAc to —NH3+.

Abstract: Three conjugation methods for use with the capsular saccharide of Streptococcus agalactiae. In the first method, reductive animation of oxidised sialic acid residue side chains is used, but the aldehyde groups are first aminated, and then the amine is coupled to a carrier via a linker. In the second method, sialic acid residues and/or N-acetyl-glucosamine residues are de-N-acetylated to give amine groups, and the amine groups are coupled to a carrier protein via a linker. In the third method, linkage is via galactose residues in the capsular saccharide rather than sialic acid residues, which can conveniently be achieved using galactose oxidase.