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Reviewed the paper are the composition and functions of Vibrio cholerae chitinolytic complex which play an important role in the maintaining and creating new forms of vibrios in the environ- ment, it is better adapted to survive in environmental.

Y. pestis adhesion pili (AP) in the native form and in the subunit form, used for immunization in one or two injections in a dose of 12-100 mu g on aluminum hydroxide, did not protect white mice and guinea pigs from experimental Y. pestis infection. The study revealed that AP produced a pronounced cytotoxic effect on macrophages and practically no influence on leukocytes. This result was confirmed in the study of luminol-dependent chemiluminescence and in the analysis of 5'-nucleotidase activity of phagocytes. These data make it possible to regard AP as Y. pestis antimacrophagal pathogenicity factor.

Primers for the detection of F.tularensis in the polymerase chain reaction (PCR) have been obtained. The method of PCR permits the identification of up to 10 F.tularensis cells in the analysis of pure and mixed cultures, as well as suspensions prepared from the organs of laboratory animals. The possibility of the simultaneous analysis of several samples makes this system for the detection of F.tularensis useful for epidemiological investigations.

With a large collection of the strains of F. tularensis isolated it has been recently shown that cultures belonging to holarctica and mediaasiatica circulate in the endemic foci of the USSR. By their biological and genetic properties the natural strains of F. tularensis were homogeneous and represented type cultures of F. tularensis. Various ecological conditions in the natural environment did not change within the last 20 years the sensitivity of the tularemia microbe to the antibacterial drugs.

The study of hemolysin activity, hemolysin-destructive factor (HDF) activity and cholerogenicity in 143 Vibrio eltor strains has revealed the existance of close relationship between cholerogenicity and hemolysin production, as well as between cholerogenicity and HDF activity. The negative character of conjugation between the HDF activity and the hemolytic activity of the strains under study has been established, which allows one to suggest the possibility of the regulating action of hemolysin on the synthesis of HDF (enterotoxin).