ANTIGEN PURIFICATION

1,261,673. Antigen purification. FARBENFABRIKEN BAYER A.G. 11 March, 1970 [15 March, 1969], No. 11679/70. Heading A5B. Foot and mouth disease (FMD) virus antigen purified from undesirable proteins is prepared by precipitating the FMD virus antigen from an aqueous solution containing FMD virus antigen and the undesirable proteins by the addition of polyethylene glycol, and separating the precipitated FMD virus antigen from the supernatant solution. Preferably a polyethylene glycol of molecular weight from 600 to 20,000 is added in the form of an aqueous solution containing from 10 to 70% by weight of polyethylene glycol. The precipitation may be carried out at a pH of 7 to 9 and at a temperature of from 0‹C to 24‹C. The mixture of virus solution and polyethylene glycol preferably contains from 15 to 35% by weight of polyethylene glycol, and may be allowed to stand for 12 to 60 hours after the addition of polyethylene glycol before the precipitated virus antigen is removed from the supernatant solution. The purified FMD virus antigen may be obtained in solid form by crystallisation or lyophilization. The purified FMD virus antigen obtained by the above process usually contains from 0.5 to 5% by weight of the polyethylene glycol. Vaccine compositions consist of or comprise the purified FMD virus antigen in admixture with a solid or liquid diluent or carrier such as an aqueous suspension of aluminium hydroxide or an isotonic buffered solution suitable for parenteral injection.