Patent
The invention relates to activated Streptococcus pneumoniae serotype 10A, 22F or 33F polysaccharides and processes for their preparation. The invention also relates to immunogenic conjugates comprising Streptococcus pneumoniae serotype 10A, 22F or 33F polysaccharides covalently linked to a carrier protein, processes for their preparation and immunogenic compositions and vaccines comprising them.
1. A process for the preparation of an immunogenic polysaccharide:carrier protein conjugate comprising Streptococcus pneumoniae serotype 10A, 22F or 33F polysaccharide covalently linked to a carrier protein, the process comprising the steps of:
(a) compounding an activated serotype 10A, 22F or 33F polysaccharide with a carrier protein, wherein said activated serotype 10A, 22F or 33F polysaccharide is obtained by a process comprising the steps of:
(i) reacting an isolated serotype 10A, 22F or 33F capsular polysaccharide with an oxidizing agent; and
(ii) quenching the oxidation reaction by addition of a quenching agent resulting in an activated Streptococcus pneumoniae serotype 10A, 22F or 33F polysaccharide; and,
(b) reacting the compounded, activated serotype 10A, 22F or 33F polysaccharide and carrier protein with a reducing agent to form a serotype 10A, 22F or 33F polysaccharide:carrier protein conjugate.
2. The process according to claim 1 , said process further comprising the step of:
(c) capping unreacted aldehydes in the serotype 10A, 22F or 33F polysaccharide:carrier protein conjugate.
3. The process according to claim 1 wherein the concentration of activated polysaccharide in step (b) is between 0.1 and 10 mg/mL, 0.5 and 5 mg/mL, or 0.5 and 2 mg/m L.
4. The process according to claim 2 , said process further comprising the step of:
(d) purifying the polysaccharide:carrier protein conjugate.
5. The process according to claim 1 wherein the activated polysaccharide is of serotype 10A.
6. The process according to claim 1 wherein the activated polysaccharide is of serotype 22F.
7. The process according to claim 1 wherein the activated polysaccharide is of serotype 33F.
8. The process according to claim 4 , wherein said process further comprising the step of:
(e) formulating the polysaccharide:carrier protein conjugate in a multivalent vaccine.
9. The process according to claim 1 , wherein step (a) and (b) are carried out in DMSO or in an aqueous solution.
10. The process according to claim 1 wherein said polysaccharide is reacted with 0.01 to 10, 0.05 to 5, 0.1 to 1, 0.5 to 1, 0.7 to 0.8, 0.01 to 0.2, 0.05 to 0.5, 0.05 to 0.2, 0.1 to 0.3 molar equivalents of oxidizing agent in step (a).
11. A process according to claim 10 wherein said polysaccharide is reacted with 0.05 to 0.3 molar equivalents of oxidizing agent in step (a).
12. The process according to claim 1 wherein the oxidizing agent is periodate.
13. The process according to claim 1 wherein the oxidizing agent is sodium metaperiodate.
14. The process according to claim 1 wherein the quenching agent is selected from glycerol, ethylene glycol, propan-1,2-diol, butan-1,2-diol or butan-2,3-diol.
15. The process according to claim 14 wherein the quenching agent is butan-2,3-diol.
16. The process according to claim 1 wherein the oxidation reaction is quenched by the addition of 0.1 to 10, 0.5 to 5, 0.5 to 3 or 0.5 to 2 molar equivalents of quenching agent.
17. The process according to claim 16 wherein the oxidation reaction is quenched by the addition of 0.5 to 2 molar equivalents of quenching agent.
18. The process according to claim 1 wherein the temperature of the reaction in step (i) and (ii) is maintained between 2 and 8° C.