Modified polysaccharide adjuvant-protein antigen conjugates, the preparation thereof and the use thereof

A polysaccharide adjuvant-antigen conjugate, comprising:

• (i) a polysaccharide having a minimum of seven glycosyl residues, said polysaccharide selected from the group consisting of a β-glucan;
• a mannan;
• a pectic polysaccharide;
• chitin;
• deacetylated chitin;
• glycol chitin;
• carboxymethyl chitin;
• hydrolyzed chitin;
• murein;
• a bacterial fructan;
• a xanthan;
• a bacterial heteropolysaccharide;
• fungal pullulan;
• and esters, sulfonates, sulfates, phosphates, ethers, and cross-linked derivatives thereof;
• (ii) one or more molecules selected from the group consisting of aromatic aldehydes, aromatic ketones, cycloalkyl aldehydes, cycloalkyl ketones, cycloalkenyl aldehydes, cycloalkenyl ketones, heterocyclic aldehydes, heterocyclic ketones, heteroaromatic ketones, heteroaromatic aldehydes, alkyl aldehydes, alkyl ketones, alkenyl aldehydes, alkenyl ketones, and mixtures thereof;
• (iii) a protein antigen capable of eliciting an immune response when covalently attached to said polysaccharide;
• wherein one or more molecules (ii) are attached to the polysaccharide (i) through a direct covalent bond or covalently via a bifunctional linker in a manner that keeps the carbonyl group of molecule (ii) intact;
• and
• wherein said protein antigen (iii) are attached to the polysaccharide (i) through a direct covalent bond or covalently via a bifunctional linker.