The Serological Relationship between Purified Preparations of Factors I and II of the Anthrax Toxin Produced In vivo and In vitro

Abstract

SUMMARY: A serological comparison on gel-diffusion plates of purified preparations of factors I and II of the anthrax toxin obtained in vitro and in vivo indicated that all but one (factor I from in vitro sources) of these preparations contained at least two major serological components. At least three serological components were involved in the total system: A (associated with factor I activity); B (associated with factor II activity); C (not associated with toxic activity). These results indicated that no preparation of factor II of the anthrax toxin so far examined was immunologically homogeneous and that the serological connexion between factor I of the anthrax toxin (produced in vivo) and the protective factor produced in vitro (Smith, 1958) was due to a common component not associated with factor I activity. There was some evidence that the method of measuring immunogenicity in certain culture filtrates of Bacillus anthracis by serological precipitation (Thorne & Belton, 1957) is not generally applicable to all products of this organism.