[Purification of a protective anthrax preparation].

An attempt was made to standardize conditions for obtaining a protective anthrax preparation. A technological scheme permitting to produce 80 mg of a purified lyophilized protective preparation with the activity of 32 immunizing units was applied. It was accepted that 1 IU was the minimal amount of the preparation which provided a survival with the mean time index of 3.0+/-0.5 of guinea pigs after a double immunization at an interval of 14 days. In vitro 1 IU also represented a minimal amount of the preparation which produced three precipitation lines (characteristic of the preparation) in immunoelectrophoretic analysis against the purified anthrax serum. Usually 1 IU in vivo and in vitro corresponded to 2.5 mg of this preparation.