[New principles for obtaining protective antigens from deep cutlures of enterobacteria]

A model of S. typhi submerged culture was used; application of the principle of sparing extraction of surface protective antigens by the action of sublethal concentrations of two damaging agents differing by the mechanism of inhibition of the processes of vital activity of the microorganisms was founded. The principle is based on regularities characteristic of cells of bacterial pupulations: a) nonhomogeneity of individual cells of the population by the resistance to the damaging agents, and b) independence of distribution in the population cells of resistance to different damaging agents. The following typhoid antigens were obtained by combined action of sublethal concentrations of hydrogen peroxide (0.25%) and formalin (0.1%): antigens with a full antigenic structure (inducing formation of O-, Vi- and H-antibodies), of low toxicity (V50 - 0.65+/-19 mg) and highly immunogenic (AU50- 0.45+/-0.25 mug) in experiments on mice.