Vaccine compositions
The present invention relates to the use of an excipient which is a compound of formula (I) or a physiologically acceptable salt or ester thereof: wherein: R 1 represents C 1-6 alkyl; R 2 represents hydrogen or C 1-6 alkyl; and R 3 represents C 1-6 alkyl, for increasing the immunogenicity of an influenza antigen, which use comprises (a) freezing, (b) heat-treating, and/or (c) freeze-drying an aqueous composition comprising the influenza antigen and the excipient.
1. A method for increasing the immunogenicity of an influenza antigen, said method comprising heat-treating an aqueous composition at 35° C. to 80° C. for 1 hour or more, the aqueous solution comprising the influenza antigen and an excipient which is a compound of formula (I) or a physiologically acceptable salt or ester thereof:
wherein:
R 1 represents hydrogen or C 1-6 alkyl;
R 2 represents C 1-6 alkyl; and
R 3 represents C 1-6 alkyl; wherein the immunogenicity of the influenza antigen is increased during the heat-treating.
2. The method according to claim 1 , in which the compound of formula (I) is dimethylglycine or trimethylglycine.
3. The method according to claim 2 , in which the compound of formula (I) is dimethylglycine.
4. The method according to claim 1 , in which the aqueous composition further comprises one or more sugars.
5. The method according to claim 4 , in which the one or more sugars are sucrose and raffinose.
6. The method according to claim 1 , in which the aqueous composition further comprises an adjuvant.
7. The method according to claim 6 , in which the adjuvant is an aluminium salt adjuvant.