The present invention relates to methods of manufacture of immunogenic glycoconjugates, in particular for use in pharmaceutical compositions for inducing a therapeutic immune response in a subject. The immunogenic glycoconjugates of the invention comprise one or more oligosaccharides or polysaccharides that are conjugated to one or more carrier proteins via an active aldehyde group. Accordingly, the invention provides methods of making (i) unsaturated microbial N-acyl derivative oligosaccharides or polysaccharides (ii) novel conjugates of unsaturated N-acyl derivatives and (iii) glycoconjugate compositions comprising conjugate molecules of fragments of microbial unsaturated N-acyl derivatives that serve as a covalent linker to one or more proteins. The invention further encompasses the use of the immunogenic glycoconjugates pharmaceutical compositions for the prevention or treatment of an infectious disease.
