Electron Microscopically Revealed Structural Elements of Bacterium Tularense and Their in Vitro and in Vivo Role in Immunologic Reactions

Abstract

The antigenic role of structural elements of Bacterium tularense was investigated. Organisms were broken up by treatment with ether or by mechanical agitation with the Mickle apparatus. The products of disruption were fractionated by centrifugation according to schemes which allowed their characterization from a structural standpoint as observed electron microscopically. The fractions were then tested as vaccines against the experimental disease in mice and as precipitating antigens against constant amounts of serum prepared by injecting washed organisms into rabbits. It was found that the vaccine potency was increased when the organisms were broken whether by ether or by mechanical agitation. Vaccine efficacy and precipitation titer of such preparations were correlated with the amount of cell wall material as observed by electron microscopy. Preparations of cell walls themselves were good vaccines.