Conjugation of staphylococcus aureus type 5 and type 8 capsular polysaccharides

A process for treating a S. aureus type 5 capsular polysaccharide comprising the step of depolymerising the capsular polysaccharide, to give a polysaccharide fragment having a β-D-FucNAc-(1→moiety at its non-reducing terminus.

A process for treating a S. aureus type 8 capsular polysaccharide comprising the step of depolymerising the capsular polysaccharide, to give a polysaccharide fragment having an α-D-FucNAc-(1→moiety at its non-reducing terminus.

A process for providing a S. aureus type 5 capsular polysaccharide derivative comprising the step of oxidising a S. aureus type 5 capsular polysaccharide having a β-D-FucNAc-(1→moiety at its non-reducing terminus to convert two vicinal hydroxyl groups in the β-D-FucNAc-(1→moiety into two aldehyde groups.

A process for providing a S. aureus type 8 capsular polysaccharide derivative comprising the step of oxidising a S. aureus type 8 capsular polysaccharide having an α-FucNAc-(1→moiety at its non-reducing terminus to convert two vicinal hydroxyl groups in the α-D-FucNAc-(1→moiety into two aldehyde groups.

A process for providing a coupled S. aureus type 5 capsular polysaccharide comprising the step of coupling to a carrier molecule a S. aureus type 5 capsular polysaccharide having a β-D-FucNAc-1→moiety at its non-reducing terminus that has been oxidised to convert two vicinal hydroxyl groups into two aldehyde groups, wherein the coupling is via one of the aldehyde groups.

A provides a process for providing a coupled S. aureus type 8 capsular polysaccharide comprising the step of coupling to a carrier molecule a S. aureus type 8 capsular polysaccharide having an α-D-FucNAc-(1→moiety at its non-reducing terminus that has been oxidised to convert two vicinal hydroxyl groups into two aldehyde groups, wherein the coupling is via one of the aldehyde groups.

A conjugate of a S. aureus type 5 or type 8 capsular polysaccharide and a carrier molecule obtained by a process comprising the steps of:

• (a) depolymerising the capsular polysaccharide, to give a polysaccharide fragment;
• (b) oxidising the fragment in order to introduce an aldehyde group into at least one saccharide residue in the fragment, to give an oxidised saccharide residue;
• and (c) coupling the oxidised saccharide residue to a carrier molecule via the aldehyde group, thereby giving the conjugate.