Modified saccharides, conjugates thereof, and their manufacture

1. A saccharide of the formula:

wherein:

T is of the formula (A) or (B):

n is integer from 1 to 100;

each Z group is independently selected from —OH, —OAc, —OC(O)N(R 1 )-L-M or —OC(O)N(R 1 )-L-C(O)H;

each Q group is independently selected from —OH, —OAc, —OC(O)N(R 1 )-L-M or —OC(O)N(R 1 )-L-C(O)H;

W is selected from —OH, —OAc, —OC(O)N(R 1 )-L-M or —OC(O)N(R 1 )-L-C(O)H;

V is —N(R 1 )-L-M or —N(R 1 )-L-C(O)H;

wherein R 1 is selected from H or C 1 -C 6 alkyl, L is a C 1 -C 12 alkylene group and M is a masked aldehyde group, and provided that the saccharide comprises at least one moiety of the formula —N(R 1 )-L-M, —N(R 1 )-L-C(O)H, —OC(O)N(R 1 )-L-M or —OC(O)N(R 1 )-L-C(O)H.

2. The saccharide of claim 1 wherein n is an integer from 15 to 25.

3. The saccharide of claim 1 wherein T is of the formula (A).

4. The saccharide of claim 1 wherein Q and Z are a mixture of OH and OAc groups in essentially the same relative proportions as in the native Neisseria meningitidis serogroup A saccharide, with the exception that one of the Q or Z groups is —OC(O)N(R 1 )-L-M or —OC(O)N(R 1 )-L-C(O)H.

5. The saccharide of claim 4 wherein one of the Q groups is —OC(O)N(R 1 )-L-M or —OC(O)N(R 1 )-L-C(O)H.

6. A process for modifying a capsular saccharide comprising the steps of:

(a) providing a capsular saccharide having a hydroxyl group;

(b) reacting the hydroxyl group with a bifunctional reagent in an organic solvent;

(c) reacting the product of step (b) with an amino compound of formula (III):

HN(R 1 )-L-M  (III)

wherein R 1 is selected from H or C 1 -C 6 alkyl, L is a C 1 -C 12 alkylene group and M is a masked aldehyde group.

7. The process of claim 6 wherein the capsular saccharide is Neisseria meningitidis serogroup A saccharide.

8. The process of claim 6 , wherein the organic solvent is an aprotic solvent.

9. The process of claim 8 wherein the aprotic solvent is selected from dimethylsulfoxide (DMSO), dimethylformamide (DMF), formamide, hexamethylphosphoramide (HMPA), hexamethylphosphorus triamide (HMPT), 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU) or dimethylacetamide (DMAC).

10. The process of claim 8 wherein the aprotic solvent is DMSO.

11. The process of claim 6 wherein the bifunctional reagent is selected from 1,1′-carbonyldiimidazole (CDI), carbonyl di-1,2,4-triazole (CDT), carbonyl di-1,2,3-benzotriazole (CDB), diphenylcarbonate, cyanogen bromide, phosgene or triphosgene.

12. The process of claim 11 wherein the bifunctional reagent is CDI.

13. The process of claim 6 wherein the amino compound in step (c) is H 2 N(CH 2 ) 3 CH(OH)CH 2 OH.

14. The process of claim 6 , further comprising the step of (d) unmasking the masked aldehyde group M, thereby providing an aldehyde compound.

15. The process of claim 14 wherein the masked aldehyde group M is —CH(OH)CH 2 OH and the unmasking step is a periodate cleavage.

16. The process of claim 14 , further comprising the step of (e) linking the aldehyde compound to a protein by a reductive amination reaction.

17. The process of claim 16 wherein the reducing agent in the reductive amination reaction is NaBH 3 CN.

18. A process for modifying a Neisseria meningitidis serogroup A saccharide comprising the steps of:

(a) providing a Neisseria meningitidis serogroup A saccharide;

(b) reacting a hydroxyl group on the saccharide with CDI in DMSO solvent;

(c) reacting the product of step (b) with H 2 N(CH 2 ) 3 CH(OH)CH 2 OH;

(d) cleaving the product of step (c) with periodate, thereby providing an aldehyde compound; and

(e) linking the aldehyde compound of step (d) to a protein by a reductive amination reaction using NaBH 3 CN.

19. A saccharide-protein conjugate wherein the saccharide and protein moieties are linked via a group of formula (IV):

A-N(R 1 )-L-NH—  (IV)

wherein A is a bond, —C(O)— or —OC(O)—; R 1 is selected from H or C 1 -C 6 alkyl; and L is a C 1 -C 12 alkylene group.

20. A saccharide-protein conjugate of claim 19 wherein R 1 is H, A is —OC(O)— and L is —(CH 2 ) 4 —.

21. The conjugate of claim 19 wherein the saccharide is a Neisseria meningitidis serogroup A saccharide.

22. The conjugate of claim 19 wherein the protein is a bacterial toxin or toxoid.

23. The conjugate of claim 22 wherein the bacterial toxin or toxoid is diphtheria toxin or toxoid.

24. The conjugate of claim 22 wherein the bacterial toxin or toxoid is CRM 197 .

25. A pharmaceutical composition comprising the saccharide-protein conjugate of claim 19 and a pharmaceutically acceptable carrier.

26. The composition of claim 25 , further comprising a vaccine adjuvant.

27. The composition of claim 26 , which is a vaccine against a disease caused by Neisseria meningitidis.

28. A method for raising an antibody response in a mammal, comprising administering the pharmaceutical composition of claim 25 to the mammal.

29. A method for immunising a mammal comprising administering to the mammal the pharmaceutical composition of claim 25 .