Purification of tetanus toxin

Abstract

The combination of multi-membrane electro-decantation and ammonium sulphate fractionation resulted in an effective purification of tetanus toxin. The most highly purified material obtained in this way contained as much as 4300–4800 Lf per mg protein nitrogen. This toxin is also pure as judged by electrophoretic and sedimentation analyses. The purified toxin yields a single, sharp band in the gel diffusion test and is therefore free of contaminating antigens as far as can be shown by this test. Consequently its use as a prophylactic should produce less side reaction. However, the antigenicity in mice, receiving a single immunising injection of formol toxoid, was shown to be only 35% of that of the crude toxoid. This fact need not detract from the value of the pure toxoid as a prophylactic, since it has other advantages which outweigh its lesser antigenicity under the conditions of these tests.