Methods for producing vaccine adjuvants
An improved method for the manufacture of an oil-in-water emulsion involves three procedures: (i) preparation of a preliminary emulsion; (ii) microfluidization of the preliminary emulsion to reduce its droplet size; and (iii) filtration of the microfluidized emulsion through a hydrophilic membrane.
1. A method for the manufacture of a squalene-containing oil-in-water emulsion vaccine adjuvant, the method comprising the step of: (i) formation of a first emulsion having a first average oil droplet size using a mechanical homogenizer, wherein the first emulsion is formed by a type II circulation of transferring its the first emulsion components from a first container to a second container through a homogenizer, and then returning them from the second container to the first container through the same homogenizer, wherein substantially all of the emulsion components from the first container are passed through the homogenizer into the second container, and then substantially all of the emulsion components from the second container are passed through the homogenizer back into the first container; and (ii) microfluidizing the first emulsion to form a second emulsion having a second average oil droplet size which is less than the first average oil droplet size.
2. The method of claim 1 , wherein step (i) comprises two or more cycles of transferring the first emulsion's components from the first container to the second container and back again.
3. The method of claim 1 , wherein the homogenizer is a rotor-stator homogenizer and wherein the microfluidization occurs in an interaction chamber having no moving parts.
4. The method of claim 1 , wherein the homogenizer provides a shear rate of up to 1×10 6 s −1 , and wherein the microfluidization occurs an interaction chamber that provides a shear rate >2.5×10 6 s −1 .
5. The method of claim 1 , comprising: (iii) filtration of the second emulsion.
6. The method of claim 1 , wherein during step (ii), the second emulsion is formed by circulating the second emulsion components through a microfluidization device a plurality of times.
7. The method of claim 6 , wherein the circulation of the second emulsion components comprises transferring the second emulsion components between a first emulsion container and a microfluidization device; and (iii) microfluidizing the first emulsion to form a second emulsion having a second average oil droplet size which is less than the first average oil droplet size.
8. The method of claim 6 , wherein the circulation of the second emulsion components comprises transferring the second emulsion components from a first emulsion container, through a microfluidization device to a second emulsion container, and then again through the microfluidization device.
9. The method of claim 1 , wherein the first average oil droplet size is 5000 nm or less.
10. The method according to claim 1 , wherein the number of oil droplets having a size of >1.2 μm in the first emulsion is 5×10 11 /ml or less.
11. The method of claim 1 , wherein the second average oil droplet size is 500 nm or less.
12. The method of claim 1 , further comprising combining the emulsion with an antigen to produce a vaccine composition.
13. The method of claim 1 , further comprising packaging the emulsion into a kit as a kit component together with an antigen component.
14. The method of claim 1 , wherein the components of the first emulsion are combined in a mixing vessel before being introduced into the homogenizer.
15. The method of claim 14 , wherein the homogenizer is a rotor-stator homogenizer.
16. The method of claim 1 , wherein the first and second containers are held under an inert gas.
17. The method of claim 6 , wherein the second emulsion is formed by circulating the second emulsion components through a microfluidization device three times.
18. The method of claim 1 , wherein the first and second emulsion containers are held under an inert gas.
19. The method of claim 1, wherein the first emulsion is formed by circulation comprising (a) a type I circulation of transferring the first emulsion components between a first container and a homogenizer followed by (b) the type II circulation.