Conjugation process

1. A process for preparing an immunogenic composition comprising conjugating an antigen to a carrier protein wherein conjugating comprises

a) activating the antigen to form an activated antigen;

b) reacting the activated antigen and a carrier protein to form an imine group linking the activated antigen to the carrier protein;

c) reductive amination of the imine group in a solution consisting essentially of a reducing agent in dimethylsulphoxide (DMSO) or dimethylformamide (DMF), wherein the reducing agent consists of sodium triacetoxyborohydride, to form a conjugated antigen; and

c″) capping unreacted carbonyl groups using sodium borohydride in a solution consisting essentially of DMSO or DMF;

or

a) activating the antigen to form an activated antigen;

b′) reacting the activated antigen and a liner to form an imine group linking the activated antigen to the linker;

c′) reductive amination of the imine group in a solution consisting essentially of a reducing agent in dimethylsulphoxide (DMSO) or dimethylformamide (DMF), wherein the reducing agent consists of sodium triacetoxyborohydride, to form an antigen-linker;

c″) capping unreacted carbonyl groups using sodium borohydride in a solution consisting essentially of DMSO or DMF;

d) reacting the antigen-linker with a carrier protein to form a conjugated antigen; and

e) mixing the conjugated antigen with a pharmaceutically acceptable excipient to form the immunogenic composition,

wherein the antigen is a bacterial capsular saccharide from a Streptococcus pneumonia serotype selected from the group consisting of 1, 2, 3, 4, 5, 6A, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19A, 19F, 20, 22F, 23F, and 33F, wherein the average molecular weight of the bacterial saccharide is between 20 kDa and 2000 kDa, and wherein step a) comprising reacting the antigen with periodate.

2. A process for preparing an immunogenic composition conjugating an antigen to a carrier protein wherein conjugating comprises

a) activating the antigen to form an activated antigen;

a′) lyophilizing the activated antigen and a carrier protein followed by reconstitution in dimethylsulphoxide (DMSO) or dimethylformamide (DMF)

b) reacting the activated antigen and a carrier protein to form an imine group linking the activated antigen to the carrier protein;

c) reductive amination of the imine group in a solution consisting essentially of a reducing agent in dimethylsulphoxide (DMSO) or dimethylformamide (DMF), wherein the reducing agent consists of sodium triacetoxyborohydride, to form a conjugated antigen; and

c″) capping unreacted carbonyl groups using sodium borohydride in a solution consisting essentially of DMSO or DMF;

or

a) activating the antigen to form an activated antigen;

a′) lyophilizing the activated antigen and a linker followed by reconstitution in DMSO or DMF;

b′) reacting the activated antigen and a linker to form an imine group linking the activated antigen to the carrier protein; and

c′) reductive amination of the imine group in a solution consisting essentially of a reducing agent in dimethylsulphoxide (DMSO) or dimethylformamide (DMF), wherein the reducing agent consists of sodium triacetoxyborohydride, to form an antigen-linker;

c″) capping unreacted carbonyl groups using sodium borohydride in a solution consisting essentially of DMSO or DMF;

d) reacting the antigen-linker with a carrier protein to form a conjugated antigen; and

e) mixing the conjugated antigen with a pharmaceutically acceptable excipient to form the immunogenic composition,

wherein the antigen is a bacterial capsular saccharide from a S. pneumonia serotype selected from the group consisting of 1, 2, 3, 4, 5, 6A, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19A, 19F, 20, 22F and 33F, wherein the average molecular weight of the bacterial saccharide is between 20 kDa and 2000 kDa, and wherein step a) comprises reacting the antigen with periodate.

3. The process of claim 1 wherein the bacterial saccharide is Haemophilus influenzae b (Hib) polysaccharide or oligosaccharide.

4. The process of claim 1 wherein the carrier protein is a protein selected from the group consisting of tetanus toxoid (TT), fragment C of TT, diphtheria toxoid, CRM197, pneumolysin, Protein D, PhtD, and PhtDE.

5. The process of claim 1 wherein the antigen and the carrier protein are lyophilised after step a).

6. The process of claim 5 wherein the antigen and the carrier protein are lyophilised in the presence of a non-reducing sugar.

7. The process of claim 1 wherein step a) comprises reacting the antigen with 0.0001-0.7 molar equivalents of periodate.

8. The process of claim 1 comprising a further step f) of mixing the conjugated antigen with further antigens.

9. The process of claim 8 wherein the further antigens comprise at least 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 S. pneumoniae saccharides.

10. The process of claim 1 wherein the conjugated antigen is mixed with an adjuvant optionally wherein the adjuvant is an aluminium salt.

11. The process of claim 1 wherein the bacterial capsular saccharide is S. pneumonia capsular saccharide 23F.

12. The process of claim 1 wherein the bacterial capsular saccharide is S. pneumonia capsular saccharide 6B.