[Brucellosis protective antigen, its chemical and immunobiological characteristics].

The data on brucella nontoxic protective antigen without any sensitizing properties isolated from the cell wall of brucella are presented. The antigen had a marked protective effect against the experimental infection for 3-4 months after a single immunization of guinea pigs.Molecular heterogeneity of the antigen, which is mainly a protein-polysaccharide complex, is given. High- and low-molecular fractions detected by gel filtration technique differed according to the chemical and immunobiological characteristics. The high-molecular fraction of the antigen was found to be highly immunogenic and serologically active.