Conjugation of staphylococcus aureus type 8 capsular polysaccharides

2:

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

3:

• The process according to claim 1, wherein the depolymerising is carried out by acid hydrolysis using acetic acid.

4:

• The process according to claim 1, wherein the average molecular mass of the fragment is between 5 and 100 kDa.

5:

• The process according to claim 1, wherein the degree of O-acetylation of the fragment is 10-90%.

6:

• The process of claim 1, wherein step (a) comprises depolymerising the capsular polysaccharide to give a polysaccharide fragment having an α-D-FucNAc-(1→moiety at is non-reducing terminus.

7:

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

8:

• The process of claim 6, wherein step (b) comprises oxidising a S. aureus type 8 capsular polysaccharide having an α-FucNAc-(1→moiety at is non-reducing terminus to convert two vicinal hydroxyl groups in the α-D-FucNAc-(1→moiety into two aldehyde groups.

9:

• 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.

10:

• The process of claim 8, further comprising (c) coupling the oxidised fragment to a carrier molecule via one of the aldehyde groups, thereby giving the conjugate.

11:

• The process of claim 1, wherein the coupling is direct coupling by reacting the aldehyde group with an amine group in the carrier by reductive amination.

12:

• The process of claim 1, wherein the coupling is via a linker by reacting the aldehyde group with an amine group in the linker by reductive amination.

13:

• The process of claim 12, wherein the linker is attached to the carrier molecule.

14:

• The process of claim 1, wherein the coupling results in a polysaccharide:protein ratio (w/w) of between 1:5 and 1:2.

15:

• A conjugate obtained by the process of claim 1.

16:

• An immunogenic composition comprising the conjugate of claim 15.