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The preparations of pilopolysaccharides (LPS) of virulent and avirulent Y. pestis strains, which have a different composition, were cultivated at different temperatures. Despite the cultivation temperature of parental cells, all LPS preparation inhibited the passive hemagglutination reaction (PHR) of the red blood cells sensitized by LPS isolated from the cultures grown at 26 degrees C by using homologous antisera. In contrast, the homologous system consisting of the red blood cells sensitized by LPS from the EV NIIEG, cultured at 37 degrees C, and the antiserum to these cells proved to be more specific and it was inhibited only by the homologous LPS isolated from the strain EV NIIEG. The similar reaction of the interaction of the red blood cells sensitized by high temperature LPS agents from plasmid-free strains with the same serum was inhibited by all plague LPS preparations. The LPS preparations from the strains Y. pestis 1146 and Y. pseudotuberculosis 9532 obtained when cultivated at 37 degrees C. RHR of the red blood cells sensitized by these preparations was inhibited by homologous LPS irrespective of the temperature of cell cultivation. In all cases, the reaction was specific for Yersinia strains and it was inhibited by LPS from Ra-Rd2 cultures, variants of Salmonella and E. coli.

Bacterial sensitivity to different various phages was examined by electro-orientation spectroscopy, fluorometry, and electron microscopy. The strains of Pseudomonas aeruginosa, Staphylococcus aureus, Yersinia pestis, Mycobacterium smegmatis, and Xanthomonas campestris were used. The fluorescence intensity of a membranotropic agent in the ANS-cell-phage system was shown to depend on the interaction of a bacterial virus and a microorganism. Fluorometric data correlated with electro-orientation spectroscopic findings. An analysis of the low-frequency site makes it possible to determine phage adsorption on the bacterial surface. The changes in electro-orientation effects at high frequencies suggest that there are barrier dysfunctions in the external membranes and that there is cellular phage reproductions. Whether fluorometry and electro-orientation spectroscopy can be further used for rapid identification of microorganisms by using phages is discussed.

The review deals with the world history and the current status of typhoid fever vaccination. It analyzes parenteral and oral killed cellular, oral live attenuated, molecular vaccines are analyzed. The results of field trials of parenteral and oral vaccines in the areas showing different epidemiology and incidence are analyzed. The problems in the designing of molecular typhi vaccines are considered. The results of designing the new generation vaccines S. typhi strains attenuated by means of site-specific mutagenesis and Vi-polysaccharide-protein conjugates are presented.

The study was undertaken to study the specific features of transformation of E. coli strains having different R-chemotypes, Y. pestis, S. minnesota R595, and S. typhi Ty21a by plasmids carrying Yersinia pestis Fra-operon which controls the formation of a plague microbe capsular F1 antigen in this microorganism. Calcium transformation was shown to be rather effective for the plasmids constructed on the basis of a cosmid vector (pFS1), rather than those designed by using the Y. pestis plasmid pPst I (pFSK3, pP3). The level of plasmid stability varied and failed to correlate with taxonomy fitting and the chemotype of a recipient strain. The cells of all recombinant strains produced F1 antigen, secreted it into the environment; the synthesis was temperature-regulated. F1 was identified both in the diffuse precipitation and serological tests. The levels of F1 antigen synthesis decreased whereas nutritious requirements for the maintenance of protein synthesis increased for bacterial strains with higher levels of LPS reduction.

Electrokinetic potentials (EKP) of the cells of R mutants of Escherichia coli and Salmonella minnesota and cells of Yersinia pestis strains EV (line NIIEG), 358/12 P-, TWJ, Java, and 231 (708) were determined, as well as EKP of lipopolysaccharide (LPS) preparations isolated from these bacteria. The electric characteristics of the cell surfaces of the strains under investigation were demonstrated to correlate with the LPS charge and the reduction extent of their molecules. Acidic hydrolysis of LPS on the cell surface resulted in the leveling of the distinctions in EKP values (their reduction to the same level). EKP values and the size of LPS micelles of the studied Y. pestis strains corresponded to those of the deep R mutants of enterobacteria, while the aggregation extent of the molecules was higher for Y. pestis.

The immunochemical study of the expression of different serovariants of Y. pestis capsular antigen in Escherichia coli HB 101, Salmonella minnesota R595 and Y. pestis EV recipient strains with different degrees of LPS reduction was made. Plasmids pFS1, pFBK7 and pFBK10 coding initial and serologically atypical variants of the capsular antigen were introduced into microbiol cells. Altered LPS structures were shown to have no influence on the serological specificity of the capsular antigen. Immunochemical activity was determined in the diffuse precipitation test, the passive hemagglutination test and the antibody neutralization test. Changes in the structure of LPS were shown to produce no effect on the serological activity of the capsular antigen coded by intact fra operon (plasmid pFS1). The transfer of hybrid plasmids pFBK7 and pFBK10 to recipient microorganisms led to the synthesis of serovariant Fl1 in recombinant strains with O-LPS, which was immunochemically different from serovariant Fl2 synthesized in strains with R-LPS.

The main protective antigen of the causative agent of plague is capsular antigen F1. The preparations of this antigen isolated from Y.pestis strain EV are characterized by a high content of polysaccharide chains of endotoxins. This can be avoided by using R-variants of bacteria as producers. In this work the comparative study of the preparations of antigen F1 obtained from Y.pestis strain EV, Escherichia coli producer strain HB101 pFS1 with the complete structure of LPS and Salmonella minnesota producer strain Re595 pFS1 with maximally reduced LPS has been made. As revealed in this study, the physico-chemical properties of these preparations (the isoelectric point, electrophoretic mobility, the molecular weight of subunits) are identical. The preparation of antigen F1 obtained from S.minnesota has been found to give the highest yield and to have the lowest content of polysaccharide admixtures. This preparation has proved to possess the maximal protective potency, which may be linked with the adjuvant and immunogenic activity of microadmixtures of glycolipid Re, contained in F1.

Protective properties of the recombinant strain Salmonella minnesota R595/GSA in experimental murine plague were studied. The recombinant vaccine ReFI possesses a high protective activity against plague with the level of survival, the LD50, indexes of immunity and the mean periods of animal death not inferior to those of the commercial vaccine. The protective properties of the live and killed recombinant ReFI vaccines in experimental murine plague are practically identical. The experimental recombinant vaccine is efficient at infecting doses up to 10(5) CFU. The live and killed vaccines are nontoxic for mice at doses up to 10(10) CFU.

The immunosorption method was shown to be suitable for the isolation of antigen pH 6, thus making it possible to obtain a highly active preparation. As eluent, 3.0 M KSCN was used. According to the data of gel filtration, the molecular weight of purified antigen pH 6 exceeds 1 x 10(6) daltons. In SDS disk electrophoresis antigen pH 6 is segregated into subunits of approximately 130,000 daltons. The preparation induces inflammatory reaction if introduced intradermally and possesses hemagglutinating and cytotoxic activity.

To improve the technological process of the preparation of vaccines from Y. pestis, the influence of different cultivation conditions on the antigenic composition of bacterial cells was studied. The study of the influence of pH (6.8-7.2), the volume of the culture medium in a flask (25-100 ml), the concentration of amino nitrogen (100-200 mg%) on the growth and phenotypic expression of Y. pestis EV [symbol: see test] antigens at 37 degrees C was studied according to the plan of a complete factor experiment. The data obtained in this study demonstrated the nonlinear dependence of the yield of viable cells on the factors chosen for the process. The presence of F1 and Pst was detected in all tested cultures. The use of the correlation field method made it possible to reveal that the production of antigen pH6 depended on the increased aeration and decreased viability index of the culture. For the production of Pst reverse dependence was revealed.

For the first time the study of the indicator system consisting of sensitized liposomes with NaF incorporated as a marker and a fluorine-selective electrode has been made and, as a result, the possibility of the potentiometric determination of the immune lysis of liposomes in the presence of complement and specific antibodies has been demonstrated. The dissolution of the lipid components (Re-chemotype glycolipid and lipid A) in the bilayer matrix obviates the necessity for converting lipid antigens into the water-soluble state in the process of serological tests. As compared with other methods, the liposomal potentiometric method for the determination of Re-chemotype glycolipid and lipid A is highly sensitive (20-40 ng/ml), rapid, technically easy to perform, cheap and does not require large volumes of samples. The disadvantages of this analytical system are the instability of liposomes and the diffusion of fluorine ions from the internal aqueous phase of vesicules. For this reason the immunoassay can be made only within 12 hours after the preparation of sensitized liposomes incorporating the marker.

The comparative study of heated corpuscular vaccines prepared from S. minnesota mutant R 595 with defective lipopolysaccharide (LPS), chemotype Re, derived from S. minnesota strain SF 1111 with unchanged LPS, and from P. aeruginosa strain PA 103, was carried out. In contrast to the vaccine from S. minnesota strain SF 1111, the vaccine prepared from the mutant with chemotype Re induced the development of cell-mediated and humoral immunity to P. aeruginosa, and its immunogenicity was close to that of the vaccine from P. aeruginosa strain PA 103.