[Ultrastructural immunochemical study of pathogenic Burkholderia capsule].

The capsular structures of Burkholderia pseudomallei, B. mallei, B. cepacia and their avirulent noncapsular mutants were studied with the use of electron ahd immunocytochemical techniques. For this purpose, antimelio-idosis monoclonal antibodies (McAb) G11 and 1 G2, epitope-aimed at capsular glycopyotein of 200 kD and outer-membrane proteins of 42 and 39 kD, were used. As revealed in this study, the typical causative agents of melioidosis and glanders formed the capsule and exhibited high virulence due to the antiphagocytic activity of 200 kD glycoprotein, whose epitopes were found to be incorporated into the capsule, in contrast to avirulent variants and B. cepacia, found to have no such structure. The recognition of the membrane determinants of McAb 1 G2 on the outer-membrane surface of the non-capsular variants of microbes known to be the causative agents of melioidosis and glanders was indicative of absence of the capsule in these microbial cells. These data concerning the role of 200 kD antigen in virulence, its structural and functional characteristics may be efffectively used in the study of the pathogenetic mechanisms of melioidosis and glanders, as well as in the construction of preparations for their immunodiagnostics and prophylaxis.

[Immune response in experimental animals immunized with Burkholderia pseudomallei surface antigens]. / Immunnyi otvet éksperimental'nykh zhivotnykh pri immunizatsii poverkhnostnymi antigenami Burkholderia pseudomallei.

The influence of the chromatographic fractions of B. pseudomallei surface antigenic complex (C, C1, D, H) on immune response in white rats and white mice was under study. These antigenic complexes were noted to produce perceptible stimulating effect on the immune system of white rats, in contrast to that of white mice. The immunization of the mice the above-mentioned fractions suppressed the phagocytic activity of peritoneal macrophages (PM) and slightly enhanced cell-mediated immunity. In experiments on white rats, fraction C induced the growth of specific antibody titers and stimulated the phagocytic activity of PM, as well as the indices of delayed hypersensitivity (DH). Fraction D showed a lower level of the induction of the phagocytic activity of PM and was inactive in the manifestation of cell-mediated immunity, but induced a high level of humoral immunity. Antigenic complexes C1 and H increased the phagocytic activity of PM and DH characteristics with a low level of antibody production. The studied fractions of the causative agent of melioidosis decreased the content of bactericidal cationic proteins (BCP) in rat blood neutrophils, and in mice a decreased content of BCP in phagocytes was registered. The fractions increased the activity of myeloperoxidase in blood neutrophils in mice and rats. As revealed with the use of immunoelectrophoresis, SDS PAAG electrophoresis and immunoblotting, the surface antigenic complex contained proteins of 18, 22, 39 kD and glycoproteins 42, 55, 90 kD. The latter glycoprotein was found in all the fractions under study, having protective properties.

[Immunobiological properties of Burkholderia pseudomallei and Burkholderia mallei capsular substances]. / Immunobiologicheskie svoistva kapsul'nogo veshchestva Burkholderia pseudomallei i Burkholderia mallei.

The biopolymer composition, immunotropic and immunogenic properties of the fractions of B. pseudomallei and B. mallei were under study. The first two capsular fractions of these agents were found to be similar in their biopolymer composition that was indicative of their close relations. At the same time the causative agents of glanders proved to have decreased content of high molecular glycoproteids and LPS fragments. In the causative agents of melioidosis, capsular fractions K3 and K4 were characterized by the domination of proteins with a molecular weight of 42-25 kD. Fraction K4 in B. pseudomallei and fraction K1 in B. mallei had pronounced immunosuppressing properties ensuring the protection of encapsulated microbial cells in the body. The biopolymers forming fractions K1, K2, K3 in B. pseudomallei and fraction K2 in B. mallei were characterized by immunomodulating properties.

[Immunotropic and immunogenic properties of Burkholderia pseudomallei surface and membrane antigens]. / Immunotropnye i immunogennye svoistva poverkhnostnykh i membrannykh antigenov Burkholderia pseudomallei.

The immunotropic and immunogenic properties of some chromatographic fractions of B. pseudomallei surface antigenic complex, as well as the preparations of B. pseudomallei outer and cytoplasmic membranes, were studied. The difference between the biopolymers under study in cytotoxicity, humoral and cell-mediated immunity characteristics, phagocytic activity were established. Some antigenic fractions (B, C, C1, H) showed perceptible protective activity (25-60%) in experiments on mice infected with B. pseudomallei virulent strain. One of the preparations of cytoplasmic membrane (CM-1) was also found to have protective properties (30%). Complex immunization with the antigenic complexes under study, introduced in combination with the immunomodulating agent Bromantan, was shown to enhance the protective effect.

[The role of capsule formation in Burkholderia mallei for its persistence in vivo]. / Rol' kapsuloobrazovaniia u Burkholderia mallei dlia ego persistentsii in vivo.

When studied in vivo (in guinea pigs) with the use of electron microscopy, B. mallei (strains C-5, 10230) were found to form a capsule. In the subacute course of infection, the encapsulated forms of B. mallei parasitized mainly in the cells of the system of mononuclear phagocytes in the liver, the spleen and the lungs. The capsule formed by B. mallei was shown to be one of the factors facilitating its persistence in the body.

[The characteristics of the interaction of Bacillus anthracis with host phagocytes in relation to the plasmid spectrum of the causative agent]. / Osobennosti vzaimodeistviia Bacillus anthracis s fagotsitami khoziaina v zavisimosti ot plazmidnogo spektra vozbuditelia.

The study revealed that after the intraperitoneal inoculation of spores of B. anthracis strains with different plasmid composition into guinea pigs the active germination of the spores both outside and inside the cells of the host occurred as early as on hour 2 of their interaction with the macroorganism. The further fate of the infective agent and the character of its interaction with peritoneal exudate cells depended on the plasmid composition of the bacilli. Thus, the presence of toxin-formation plasmid PXO1 and capsule-formation plasmid PXO2 in B. anthracis permitted the successful adaptation of these bacilli to the conditions of the macroorganism, while the absence of such plasmids made them nonviable in this environment. The presence of plasmid PXO1 in B. anthracis permitted the manifestation of their cytopathic effort on the cells and the presence of plasmid PXO2 only gave the bacilli incomplete protection from phagocytosis.

[Pseudomonas pseudomallei and Pseudomonas mallei--capsule-forming bacteria]. / Pseudomonas pseudomallei i Pseudomonas mallei--kapsuloobrazuiushchie bakterii.

The specific features of the submicroscopic structure of the causative agents of melioidosis and glanders, grown in culture media and at the initial stages of experimental infection in guinea pigs and golden hamsters, were studied with the use of electronic cytochemistry and immunocytochemistry. P. pseudomallei and P. mallei were found to be capsule-forming bacteria. According to the data obtained with the use of electronic cytochemistry, the basis of the capsular substance P. pseudomallei and P. mallei is formed by polysaccharide biopolymers protecting these bacteria from phagocytosis.

[The effect of the acid exopolysaccharide produced by the causative agent of melioidosis on macrophage function]. / Vliianie kislogo ékzopolisakharida, produtsiruemogo vozbuditelem melioidoza, na funktsional'nuiu aktivnost' makrofagov.

Acid exopolysaccharide of the melioidosis agent, isolated from the slime of alysogenic strain of Pseudomonas pseudomallei SVBDO-141 inhibits the capture of sheep erythrocytes--55Fe by mouse peritoneal macrophages. Administration of the sheep erythrocytes--55Fe, sensibilized by acid exopolysaccharide was proved not to have an antiphagocytic effect. Inhibition of phagocytic macrophagal activity depends on the conditions of isolation of acid exopolysaccharide.

[The interaction of the causative agent of melioidosis with the host's alveolar macrophages]. / Vzaimodeistvie vozbuditelia melioidoza s al'veoliarnymi makrofagami khoziaina.

Studies were carried out on guinea pigs and albino rats, intranasally infected with P. pseudomallei C-141. The cells of bronchovesicular exudate were obtained from animals 1, 4 and 24 hours after infection. Electron microscopy was applied to study the process of interaction of the agent and alveolar macrophages. Bacteria were shown to form a capsule which permitted avoiding phagocytosis, when entering the host respiratory system. Microbes that failed to form a capsule were absorbed by macrophages and enclosed in a phagosome. Then some bacteria were destroyed by the lysosomal enzymes, the other synthesized a capsule, which protected them against the effect of phagolysosome content. There were also such microbes which escaped from a phagosome prior to fusion with lysosomes and parasitized in phagocytic cytoplasma forming a capsule there. By the end of the first 24 hours of observation the intact encapsulated microbe species were found to prevail in the host cells.

[The parasitism characteristics of the causative agent of melioidosis in the host cells]. / Osobennosti parazitirovaniia vozbuditelia melioidoza v kletkakh khoziaina.

The electron microscopic study of the damaged areas of the lungs, liver, spleen and lymph nodes of guinea pigs infected with two P. pseudomallei virulent strains C-141 and 100 has revealed that this organism is a facultative intracellular parasite and exhibits tropism to reticuloendothelial cells of the body, parasitizing both in "professional" phagocytes (mononuclear, phagocytes, polymorphonuclear leukocytes) and "nonprofessional" phagocytes (capillary endotheliocytes, splenic and lymph-node reticulocytes). In the course of their intracellular development P. pseudomallei have been shown to form capsules protecting the pathogens from the unfavorable action of the protective mechanisms of the host cells.

[Capsule formation in the causative agent of glanders]. / Izuchenie kapsuloobrazovaniia u vobuditelia sapa.

Electron-microscopic and electron-cytochemical method were used to indicate the capability of Pseudomonas mallei (str. N 10230) to produce extracellular slime during the agent growth on the meat-peptone agar. In case of guinea pigs infection the agent forms a capsule that defends the pathogen from phagocytosis.

[The ultrastructural characteristics of the causative agent of melioidosis and its interaction with phagocytes in vivo]. / Osobennosti ul'trastruktury vozbuditelia melioidoza i ego vzaimodeistviia s fagotsitami in vivo.

The electron microscopic studies have established that the virulent strain of Pseudomonas pseudomallei C-141, an agent of melioidosis, being intraperitoneally administered to guinea pigs, forms in vivo three morphological variants. One variant is capsule-free, while two others have a capsule which in the second variant may be referred by its characters to the microcapsule and in the third one to the macrocapsule. It has been shown that under the interaction of these three morphological variants with the microorganism cells the bacteria of the first and second variants are absorbed by phagocytes, whereas the microbial cells of the third morphological variant are more resistant to the phagocytosis.