Immuno-adjuvant emulsion
The invention relates to an oil-in-water adjuvant emulsion which comprises at least: squalene, an aqueous solvent, a polyoxyethylene alkyl ether nonionic surfactant, a hydrophobic nonionic surfactant, which emulsion is thermoreversible, and wherein 90% of the population by volume of the oil drops has a size less than 200 nm. The invention also relates to a process for preparing an immunogenic composition according to which at least one vaccine antigen is mixed with an oil-in-water emulsion, wherein the oil-in-water emulsion is obtained by means of a temperature-variation phase-inversion process.
1. An oil-in-water adjuvant emulsion which comprises:
i) squalene,
ii) an aqueous solvent,
iii) a polyoxyethylene alkyl ether hydrophilic nonionic surfactant, and
iv) a hydrophobic nonionic surfactant,
wherein the emulsion is thermoreversible and wherein 90% of the population by volume of the oil drops has a size less than 200 nm.
2. The emulsion of claim 1 wherein the polyoxyethylene alkyl ether is of formula CH 3 —(CH 2 ) x —(O—CH 2 —CH 2 ) n —OH, in which n is an integer from 10 to 60, and x is an integer from 11 to 17.
3. The emulsion as claimed in claim 1 , wherein 90% of the population by volume of the oil drops has a size less than 160 nm.
4. The emulsion as claimed in claim 3 , wherein 90% of the population by volume of the oil drops has a size less than 150 nm.
5. The emulsion as claimed in claim 1 , wherein 50% of the population by volume of the oil drops has a size less than 100 nm.
6. The emulsion as claimed in claim 5 , wherein 50% of the population by volume of the oil drops has a size less than 90 nm.
7. The emulsion according to claim 1 , which also comprises at least one alditol.
8. The emulsion as claimed in claim 1 , wherein the hydrophobic nonionic surfactant is a sorbitan ester or mannide ester surfactant.
9. The emulsion according to claim 1 , wherein the polyoxyethylene alkyl ether surfactant is polyoxyethylene(12) cetostearyl ether.
10. The emulsion according to claim 7 , wherein the alditol is chosen from glycerol, erythritol, xylitol, sorbitol and mannitol.
11. The emulsion according to claim 1 , wherein the hydrophobic nonionic surfactant is sorbitan monooleate.
12. The emulsion according to claim 1 , wherein the amount of squalene is between 5 and 45%.
13. The emulsion according to claim 1 , wherein the amount of polyoxyethylene alkyl ether surfactant is between 0.9 and 9%.
14. The emulsion according to claim 1 , wherein the amount of hydrophobic nonionic surfactant is between 0.7 and 7%.
15. The adjuvant emulsion according to claim 1 , which comprises:
i) 32.5% of squalene,
ii) 6.18% of polyoxyethylene(12) cetostearyl ether,
iii) 4.82% of sorbitan monooleate, and
iv) 6% of mannitol.
16. The emulsion according to claim 1 , which also comprises an alkylpolyglycoside.
17. The emulsion according to claim 1 , which also comprises a cryoprotective agent.
18. A process for preparing an immunogenic composition comprising at least one vaccine antigen and a squalene-containing oil-in-water emulsion, the process comprising making the squalene-containing oil-in-water emulsion according to claim 1 by a phase-inversion temperature process.
19. The process as claimed in claim 18 , wherein the oil-in-water emulsion is prepared by cooling a water-in-oil inverse emulsion which comprises:
i) squalene,
ii) an aqueous solvent,
iii) a polyoxyethylene alkyl ether hydrophilic nonionic surfactant, and
iv) a hydrophobic nonionic surfactant.
20. The process as claimed in claim 19 , wherein the water-in-oil inverse emulsion is prepared by mixing squalene, an aqueous solvent, a polyoxyethylene alkyl ether hydrophilic nonionic surfactant, and a hydrophobic nonionic surfactant to obtain a coarse oil-in-water emulsion, and then heating the emulsion to at least its phase inversion temperature in order to obtain an inverse emulsion.
21. The process as claimed in claim 19 , wherein the water-in-oil inverse emulsion is prepared by:
separately heating (a) the aqueous phase comprising the aqueous solvent and the polyoxyethylene alkyl ether nonionic surfactant and (b) the oily phase comprising the squalene and the hydrophobic surfactant, and
mixing the pre-heated aqueous and oily phases.
22. The process as claimed in claim 21 , wherein:
the aqueous and oily phases are heated, separately, to a temperature below the phase inversion temperature of the emulsion,
the two phases are mixed to obtain an oil-in-water emulsion,
the oil-in-water emulsion obtained is then heated to a temperature at least equal to the phase inversion temperature of the emulsion, in order to obtain a water-in-oil inverse emulsion.
23. The process as claimed in claim 18 , wherein the phase inversion temperature is between 45 and 80° C.
24. The process as claimed in claim 23 , wherein the phase inversion temperature is between 50 and 65° C.
25. The process as claimed in claim 18 , which also comprises at least one lyophilization step.
26. An immunogenic composition prepared according to the process of claim 18 .
27. An immunogenic composition comprising an antigen and an emulsion according to claim 1 .