Methods for providing a homogenous solution of lyophilized mutant diptheria toxin in dimethylsulfoxide
A method is described for reconstituting lyophilized mutant diphtheria toxin in dimethyl sulfoxide for use in producing pneumococcal capsular polysaccharide mutant diphtheria toxin conjugates.
1. A method for making a homogeneous solution of mutant diphtheria toxin (mDT) in anhydrous dimethyl sulfoxide (DMSO), the method comprising:
(a) providing a dried composition of mDT; and
(b) reconstituting the dried composition to a final concentration of 10 mg/mL or less in anhydrous DMSO by adding the anhydrous DMSO to the dried composition over a time period of two minutes or less and mixing for at least 10 seconds to provide a homogenous solution comprising the mDT.
2. The method of claim 1 , wherein the dried composition is prepared by sublimative drying of an aqueous solution comprising the mDT wherein the sublimative drying is selected from lyophilization and radiant energy vacuum (REV) dehydration.
3. The method of claim 2 , wherein the sublimative drying comprises freezing the aqueous solution in the form of cakes or lyosphere beads.
4. The method of claim 2 , wherein the sublimative drying process comprises bulk drying performed in a container selected from the group consisting of metal tray, plastic tray, plastic bag, and class I tubing vials.
5. The method of claim 1 , wherein the dried composition is prepared by sublimative drying of an aqueous solution comprising mDT to produce the dried composition, wherein the aqueous solution further comprises about 0.5% (w/v) or more sucrose and a buffer, and the sublimative drying is selected from lyophilization and radiant energy vacuum (REV) dehydration.
6. The method of claim 5 , wherein the buffer is a Histidine, Succinate, MES, MOPS, HEPES, or Acetate buffer in a pH range of 5.0-7.0.
7. The method of claim 5 , wherein the buffer is a Phosphate or a Citrate buffer in a pH range of 5.0-7.0.
8. The method of claim 1 , wherein the dried composition has a moisture content of less than 6%.
9. The method of claim 1 , wherein the mixing in step (b) is performed in 120 minutes or less.
10. The method of claim 1 , wherein the homogenous solution comprising the mDT is conjugated to activated polysaccharides six hours or less following the reconstituting.
11. The method of claim 1 , wherein the homogenous solution comprising the mDT has no detectable aggregation.
12. The method of claim 1 , wherein the homogenous solution comprising the mDT has no detectable beta-sheet mediated aggregation.
13. The method of claim 1 , wherein the homogenous solution comprising the mDT has no detectable beta-sheet mediated aggregation as determined by Fourier-transform infrared spectroscopy or dynamic light scattering.