Conjugation of Streptococcal Capsular Saccharides
AssigneeGlaxosmithkline Biologicals SA
InventorFrancesco Berti
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Abstract
Three conjugation methods for use with the capsular saccharide of Streptococcus agalactiae. In the first method, reductive amination of oxidized sialic acid residue side chains is used, but the aldehyde groups are first aminated, and then the amine is coupled to a carrier via a linker. In the second method, sialic acid residues and/or N-acetyl-glucosamine residues are de-N-acetylated to give amine groups, and the amine groups are coupled to a carrier protein via a linker. In the third method, linkage is via galactose residues in the capsular saccharide rather than sialic acid residues, which can conveniently be achieved using galactose oxidase.
Claims20
A process for preparing a conjugate of a Streptococcus agalactiae capsular saccharide and a carrier molecule, comprising the steps of:
- (a) oxidising a S. agalactiae capsular saccharide in order to introduce an aldehyde group into at least one terminal sialic acid residue in the saccharide;
- (b) subjecting the aldehyde group to reductive amination with ammonia or a primary amine, to give a —CH2-linked amine;
- (c) reacting the —CH2-linked amine with a bifunctional linker, to give an activated saccharide;
- and (d) reacting the activated saccharide with a carrier molecule, thereby giving the conjugate.
A conjugate comprising a Streptococcus agalactiae capsular saccharide moiety joined to a carrier molecule via a linker moiety, wherein the linker moiety is attached to a sialic acid residue in the capsular saccharide moiety.
The process of claim 17, wherein reductive amination involves an ammonium salt in combination with a reducing agent.
The process of claim 20, where the reactions with both the saccharide and the carrier involve amines, and wherein the linker has formula X-L-X, where:
- the two X groups are the same as each other and can react with the amines;
- and L is a linking moiety in the linker.
The process of claim 21, wherein X is N-oxysuccinimide.
The process of claim 22, wherein the linker is adipic acid N-hydroxysuccinimide diester.
A process for preparing a conjugate of a Streptococcus agalactiae capsular saccharide and a carrier molecule, comprising the steps of:
- (a) de-N-acetylating the capsular saccharide, to give a de-N-acetylated saccharide;
- (b) reacting the de-N-acetylated saccharide with a bifunctional linker, to give an activated saccharide;
- and (c) reacting the activated saccharide with a carrier molecule, thereby giving the conjugate.
A process for preparing a conjugate of a capsular saccharide and a carrier molecule, comprising the steps of:
- (a) oxidising a capsular saccharide in order to introduce an aldehyde group into at least one galactose residue in the saccharide, to give a modified galactose residue;
- and (b) coupling the modified galactose residue to a carrier molecule.
Dependencies are inferred from the claim text.