[Antigenic specificity of Vibrio cholerae O139 nitrosoguanidine mutants]. / Antigennaia osobennost' nitrozoguanidinovykh mutantov Vibrio cholerae O139.

The action of nitrosoguanidine (NG) on the culture of V. cholerae O139 P-16064 resulted in the appearance of mutant 16064 NG6, not agglutinating with commercial diagnostic serum O139. Its incapacity of agglutination was due to the sorption of the specific serum with strains V. cholerae O22 and R-variant RCA-385, which caused the loss of antibodies to common determinants. Experiments with the sorption of immune sera made it possible to suggest that one of the determinants of LPS O139, phosphate-galactose, was absent in NG mutant.

[Aspects of Vibrio cholerae lipopolysaccharide]. / Osobennosti lipopolisakharida Vibrio cholerae.

In this review information on the chemical structure, biosynthesis, antigenic and biological properties of V. cholerae lipopolysaccharide (LPS) is presented. The specific structural feature of this LPS is a small size of the polysaccharide chain of O-antigen. In vibrios of serogroup O 139 it is oligosaccharide. The modification of the O-chain (methylation of individual sugars, shortened chain, etc.) plays an essential role in the antigenic specificity of V. cholerae LPS. All these factors affect of endotoxin function, the microbial resistance to external influences. V. cholerae LPS takes part in the formation of microcapsules and biofilms. The evolutional development of V. cholerae in this direction determines, to some extent, their increased resistance in the environment. In human body the heterogeneity of the LPS composition permits the preservation of vibrios and ensures, together with cholerogen, their pathogenetic action.

[A comparative study of the immunogenicity of a bacterial mass and of the cell membranes of Vibrio cholerae grown in vivo and in vitro]. / Sravnitel'noe izuchenie immunogennosti bakterial'noi massy i kletochnykh obolochek Vibrio cholerae, vyrashchennykh in vivo i in vitro.

The comparative study of the immunogenic and protective properties of V. cholerae, grown in vivo and in vitro, and cell walls and lysates obtained from these organisms. In the mouse protection test the efficacy of preparations obtained from vibrios grown in vivo did not exceed that of the preparations obtained from V. cholerae agar cultures.

[The isolation of capsule-free variants of Francisella tularensis]. / Poluchenie beskapsul'nykh variantov Francisella tularensis.

New methods (selection in medium T with 20% Tween-80, inducing mutations leading to the appearance of resistance to triphenyl tetrazolium chloride or indoxyl phosphate) helped create a collection of F. tularensis stable non-capsular variants from strains of different subspecies. The characteristic features of all F. tularensis cap- variants include inability to serologic tests with erythrocytic diagnosticum, the absence of capsular antigens, sensitivity to normal human serum.

[The glycolipid composition of Francisella tularensis strains with different degrees of attenuation]. / Glikolipidnyi sostav shtammov Francisella tularensis razlichnoi stepeni attenuatsii.

The glycolipid composition of F. tularensis strains was investigated by silica gel thin-layer chromatography. Vaccine strains in contrast to virulent ones lacked glycolipid 8, possessed new glycolipid 8-a and a higher level of glycolipid 7. Low immunogenic strains had a decreased content of glycolipids, while avirulent non-immunogenic strain (15-a) nearly completely lost them. Thus, the glycolipid composition is associated with the level of attenuation, virulence and immunogenicity of F. tularensis.

[The C antigen of Francisella tularensis]. / C-antigen tuliiaremiinogo mikroba.

A new envelope antigen C, specific for virulent strains of Francisella tularensis, was revealed by immunodiffusion analysis. In contrast to antigens A and P this antigen is common for Francisella and Brucella. C-antigenic lipid fraction was obtained by chloroform-ethanol (1:1) extraction of bacterial slime. This fraction contained carbohydrates (31.6%) without proteins and detected by TLC glycolipid, which proved glycolipid nature of C-antigen. Introduction of C-fraction or alive F. tularensis resulted in accumulation of C. precipitins in blood serum.

[The glycolipids of the causative agent of tularemia]. / Glikolipidy vozbuditelia tuliaremii.

Up to 10 glycolipids were detected in F. tularensis with the use of thin-layer chromatographic techniques. These glycolipids were slime antigens of F. tularensis membrane. Attenuated F. tularensis strains were found to have defects in their glycolipid composition: in the vaccine strain glycolipid 8 was replaced by more polar lipid 8-a; the avirulent strain had only two glycolipids, and one of them was not typical for virulent strains. Considering that glycolipids differed from entero-bacterial Vi-antigen in their physical-chemical and biological properties, the suggestion was made that the use of the symbol "Vi" to denote the surface substances of F. tularensis should be abolished.

[The dynamics of antibody formation to a vaccinal strain of Francisella tularensis in different immunization regimens]. / Dinamika obrazovaniia antitel k vaktsinnomu shtammu Francisella tularensis pri razlichnykh skhemakh immunizatsii.

The use of different schemes of albino mice immunization either by living or by killed preparations of the vaccine strain of Francisella tularensis when obtaining monoclonal antibodies to the tularemia microbe made it possible to reveal definite regularities in the dynamics of antibody formation. The highest titres of antibodies in sera of animals-donors of splenocytes were obtained during the daily (for 3 days) intraperitoneal immunization of mice with living vaccine or with its thrice administration to the spleen thrice with the interval of 10 days. Revaccination against a background of high titres of antibodies decreased their quantity in blood serum of mice, while that against a background of low titres increased them.