Meningococcus serogroup X conjugate
The invention provides a conjugate of a Neisseria meningitidis serogroup X capsular polysaccharide and a carrier molecule. The conjugate is typically made by (a) oxidizing a primary hydroxyl group in the capsular polysaccharide, to give an oxidized polysaccharide with an aldehyde group; and (b) coupling the oxidized polysaccharide to a carrier molecule via the aldehyde group, thereby giving the conjugate. The conjugate may be part of an immunogenic composition. This composition may comprise one or more further antigens, particularly capsular polysaccharides from serogroups A, W135, C and Y and conjugated forms thereof. The composition may be in an aqueous formulation. The composition is useful as a vaccine, e.g. for raising an immune response in a mammal. The invention also provides processes for making the conjugate.
1. A composition comprising a conjugate of a Neisseria meningitidis serogroup X capsular polysaccharide and a carrier protein, wherein conjugation of the capsular polysaccharide to the carrier protein is direct, wherein the carrier protein is conjugated to oxidized primary hydroxyl group of 1-10% of the residues in the capsular polysaccharide, and wherein the conjugate comprises less than 50% free saccharide released from the conjugate after 28 days at 37° C.
2. The composition of claim 1 , wherein the conjugation is with a primary amine group on the carrier protein.
3. The composition of claim 1 , wherein a hydroxyl group in the polysaccharide is covalently linked to an amino group in the carrier protein.
4. The composition of claim 1 , wherein the carrier protein is a diphtheria toxoid, tetanus toxoid, CRM197 or Haemophilus influenzae protein D.
5. The composition of claim 1 , further comprising one or more additional antigens.
6. The composition of claim 1 , further comprising a Neisseria meningitidis serogroup A capsular polysaccharide.
7. The composition of claim 1 , wherein the composition is in an aqueous formulation.
8. A vaccine comprising the composition of claim 1 , wherein the conjugate is purified.
9. A method of raising an immune response to a Neisseria meningitidis serogroup X capsular polysaccharide in a mammal comprising administering to the mammal an immunologically effective amount of the composition of claim 1 .
10. A pharmaceutical composition comprising (a) the composition of claim 1 and (b) a pharmaceutically acceptable carrier, wherein the composition is in an aqueous formulation.
11. The pharmaceutical composition of claim 10 , further comprising one or more additional antigens.