[Prevalence of glucosyl transferase Lgt among Legionella pneumophila strains isolated from various sources].

AIM: Determine various members of Lgt glucosyl transferase family among microorganisms of Legionellaceae genus from museum collection and legionellae strains recently isolated in the Russian Federation and Germany. MATERIALS AND METHODS: Presence of 3 types of glucosyl transferase were determined in 73 strains of L. pneumophila and Legionella spp. Glucosyl transferase activity of 3 types (Lgt1, Lgt2 and Lgt3) was determined by western blotting and PCR method. RESULTS: Lgt1 and Lgt3 were detected only in members of L. pneumophila independently of isolation source and were absent in Legionella spp. strains. Lgt2 is absent in Legionella spp. strains and is detected in not all the L. pneumophila strains. Comparative analysis of detection frequency of Lgt2 in clinical strains and L. pneumophila strains isolated from the environment showed that the protein is detected in clinical strains more frequently (46%) compared with strains from the environment (23%). CONCLUSION: Lgt1 and Lgt3 as species specific markers could be used for practical purposes for identification of L. pneumophila strains. High frequency of Lgt2 isolation in clinical strains of L. pneumophila isolated from lung tissue in lethal cases of legionellosis compared with strains isolated from the environment requires a more detailed study of functional activity and substrate specificity of the glucosyl transferase.

[Pathogenicity factors of bacteria with glycosylating activity].

A and B toxins of Clostridium difficile, a-toxin of C. novyi, lehal toxin of C. sordellii, and TpeL toxin of C. perfringens belong to the group of the so-called large Clostridium toxins. These toxins modify low-molecular weight guanosine triphosphate-binding proteins of the Rho/Ras family by their glycosylation that results in inactivation of major signal pathways in eukaryotic cells. Lgt glycosyltransferases, a new group of pathogenicity factors also capable of inactivating eukaryotic substrates via glycosylation, have recently been identified in Legionella. They are transported into cytoplasm of eukaryotic target cells by type 4 secretory system of Legionella. After translocation, the enzyme inhibits protein synthesis by attaching glucose residue to Ser53 of 1A elongation factor. The available data suggest an important role of bacterial glycosylating factors in the action of pathogens causing infectious diseases.

[Detection of clostridia toxin markers in different types of the course of acute intestinal infections].

The purpose of the investigation was to study the detection rates of markers and the level of C. diffcile A and B toxins and C. perfringens type A enterotoxin in patients with acute intestinal infections (AII). Two hundred and seventy-three patients with AII of varying etiology were followed up. According to the clinical syndrome, the patients were divided into 3 groups: (1) patients with the gastroenteritic (GE) type; (2) those with the gastroenterocolitic (GEC) type; (3) those with enterocolitic (EC) type. The circulation of markers of C. difficile A and B toxins and C. perfringens type A enterotoxin was studied, by employing the immunological test systems in the coagglutination test using the plates. The higher levels of antigens of all toxins were identified in the acute period of the disease in the GE and EC types than in the GEC type. There was a short increase in the levels of antigens of the test toxins in the GEC type and a gradual decrease in the GE and EC types. By discharge from hospital, the markers of toxins (more commonly of C. diffcile A) were preserved in 16.4% of the patients mainly in the GEC type.

[Production of recombinant fragment of VacA protein and development of non-invasive method for the diagnosis of Helicobacter pylori infection].

Vacuolizing toxin (VacA) Helicobacter pylori is an important factor of pathogenicity of Helicobacter pylori and a basic marker in the diagnosis of helicobacteriosis and related diseases. A coagulation-based diagnostic test-system was elaborated for the detection of VacA in clinical samples. A fragment of vacA was cloned, for the purpose, in Escherichia coli and expressed in preparative quantities; the coded protein was purified and used in raising the diagnostic serum. The thus designed coagulating test-system was successfully tested under the modeling conditions with clinical samples. Therefore, the designed express method can be used for the invasion-free determination of VacA in patients with gastric and duodenal pathologies.

[Pathogenicity of bacteria and the actin cytoskeleton]. / Patogennost' bakterii i aktinovyi tsitoskelet.

Actin system of eukaryotic cells creates the driving force for alteration of the phagocytic cytoplasmatic membrane shape, which is needed for cell movement in the space and for microorganism capturing. Manipulation by actin cytoskeleton mediated through specialized bacterial products can promote proliferation of bacteria in the host. Published reports indicate that bacterial regulation of the actin system activity can be carried out by two modes: 1) by bacterial interactions with surface receptors regulating the cytoskeleton status and 2) by introduction of bacterial products targeted to the cytoskeleton components into the cells. Intracellular pathogens (Legionella) possess ligands which interact with eukaryotic receptors and type IV secretion system fit for translocation of heretofore unknown effector molecules into the cytoplasm. This can result in stimulation of actin polymerization activity and accelerated phagocytosis of the bacteria with rapid multiplication in tissues. By contrast, representatives of extracellular pathogens (Clostridium) produce substances penetrating inside the eukaryotic cells and destroying the actin network, thus making capturing and intracellular digestion of these microorganisms impossible.

[Changes in the virulence factor expression level in Listeria monocytogenes under various environmental conditions]. / Izmenenie urovnia ékspressii faktorov virulentnosti Listeria monocytogenes pod vliianiem vneshnikh uslovii.

Effects of chelators Chelex-100 and activated charcoal on the production of proteins responsible for virulence of Listeria monocytogenes, facultative intracellular parasite were studied. Bivalent cation chelator Chelex-100 stimulates the production of only thiol-dependent hemolysin listeriolysin O. The presence of activated charcoal, a nonspecific chelator, in culture medium stimulated the expression of listeriolysin O and other main virulence factors by increasing the level of their transcription.

[Gene-engineering approach for the production of A and B toxin fragments for diagnostic and immunotherapeutic use in Clostridium difficile infection]. / Genno-inzhenernyi podkhod k polucheniiu fragmentov toksinov A i B dlia diagnostiki i immunoterapii Clostridium difficile infektsii.

Clostridium difficle is a causative agent of severe and difficult-to-diagnose human infections. Toxins A and B, which modify the RAS-like proteins of eukaryotic cells, are the major factor in the pathogenicity of the discussed causative agent. These very toxins are considered as the key components of the developed diagnostic and therapeutic-and-preventive preparations. The C-terminal fragments of toxins A and B as well as hybrid products, consisting of fragments of both toxins, were cloned, within the present case study, by using the pET28 plasmid vector. The recombinant plasmids were transformed into strains Escherichia Coli BL21 (DE3), and they were used later to produce the appropriate proteins. The purified protein preparations were isolated from the ultrasound bacterial-cell lysate by using the method of metal-affinity chromatography to be used later in the production of hyper-immune rabbit sera.

[Cloning and expression of the phosphatidylinositol-specific phospholipase C gene from Listeria monocytogenes]. / Klonirovanie i ékspressiia gena fosfatidilinozitolspetsifichnoi fosfolipazy s Listeria monocytogenes.

The gene for phosphatidylinositol-specific phospholipase C (PI-PLC) of Listeria monocytogenes has been cloned and shown to be expressed in Escherichia coli cells from own as well as from the lactose gene promoter. The recombinant plasmid has been constructed on the basis of pRIT2T vector and carries the hybrid gone. 3-end of which is a fragment of protein A gene of Staphylococcus aureus. 3-end is a gene for phospholipase plcA, both in the same reading frame. The resultant construction is shown to code in Escherichia coli cells for the hybrid recombinant protein A:Pl-PLC. Purified preparation of the hybrid protein and polyclonal rabbit antiserum to it were obtained. The obtained antiserum to the hybrid protein containing phospholipase as en C-end domain has been shown to react specifically to phospholipase in Escherichia coli recombinant strain harbouring the constructed recombinant plasmid as well as the one in the culture fluid of listeria.

[Production of recombinant fragments of the Clostridium tetani neurotoxin for the development of new immune-prophylaxis preparations against tetanus]. / Poluchenie rekombinantnykh fragmentov neirotoksina Clostridium tetani dlia razrabotki novykh sredstv immunoprofilaktiki stolbniaka.

Tetanus belongs to dangerous infection diseases, whose effective prevention can be ensured by vaccines. The acting substance of tetanus vaccines, presently in use, is a partially purified and deprived-of-lethal-action Clostridium tetani neurotoxin. The construction of a subunit preparation on the basis of toxin fragments obtained through gene engineering could be a method aimed at promoting the quality of the used tetanus vaccines. With this goal in mind, we built, within the present case study, the expressing genetic constructions and obtained, in the pure form, an extensive tetanus-vaccine chain with its C-terminal (Hc) fragment, hydride peptides, containing the Hc-fragment and C-terminal fragment of toxin B C. difficile, as well as Hc-fragment and S3 collagen-binding domain of collagenase C. histolyticum. The thus obtained proteins can be used in testing their immunogenic and protective properties, while the conducted study could be a basis for further research of a new-generation vaccine against tetanus and other human infection diseases.

[Autoregulation of expression of secreted proteins in Listeria monocytogenes]. / Avtoreguliatsiia ékspressii sekretiruemykh belkov u Listeria monocytogenes.

The spectrum of proteins secreted by L. monocytogenes greatly depends on the composition of the cultivation medium. The introduction of activated charcoal (AC) into brain heart infusion (BHI) leads to the secretion of a number of additional proteins with mol.wt. ranging between 20 and 100 kD, whose production is not observed in pure BHI. The effect depends on the absorption capacity of AC: when adsorption capacity is reduced due to a decrease in the concentration of AC or its preliminary saturation with the components of the cultivation medium a drop in the level of the production of additional proteins is observed. The preliminary treatment of the medium with AC with its subsequent elimination prior to inoculation doses not change the spectrum of secreted proteins, though greatly inhibits the growth of L. monocytogenes. The data obtained in this investigation indicate that the effect produced by AC is based on the elimination of some product of L. monocytogenes vital activity from the cultivation medium; this product acts as the autoregulator of the synthesis of a number of secreted proteins.

[Cytolysin as an immunoserological marker of Legionella pneumophila]. / Tsitolizin kak immunoserologicheskii marker Legionella pneumophila.

Coagglutination test (CoaT), radioimmunoassay (RIA) and ELISA were used for detection of cytolysin produced by L. pneumophila. The sensitivity of RIA was 100 ng/ml, CoaT--10-20 ng/ml, ELISA--1 ng/ml. To determine cytolysin production among various strains and species of Legionella, the authors studied bacterial ultrasonic lysates. All 11 strains of L. pneumophila tested were cytolysin-positive. L. longbeachae, L. bozemanii and L. dumoffii strains failed to produce cytolysin. The authors believe that an antigen of cytolysin can be used for identification of L. pneumophila.

[Characteristics of the cytolysin of Legionella pneumophila]. / Kharakteristika tsitolizina Legionella pneumophila.

A thermolabile cytolysin was purified from liquid culture of L. pneumophila. Its homogenicity was determined by the Ouchterlony double immunodiffusion and SDS-electrophoresis in polyacrylamide gel. The molecular weight of cytolysin was ca. 37 kDa. Analysis of amino acid composition revealed a high proportion of aromatic, dicarbonic amino acids, and methionine. The minimal cytolytic concentration for CHO cells and erythrocytes was ca. 1 microgram/ml: Purified cytolysin in doses of 10-60 micrograms caused haemorrhage and necrosis when injected i. c. into guinea pigs.

[Conditions for Legionella pneumophila cultivation that affect cytotoxin production]. / Izuchenie uslovii kul'tivirovaniia Legionella pneumophila, vliiaiushchikh na produktsiiu tsitotoksina.

Experiments in CHO cell cultures have demonstrated the cytotoxic action of culture filtrates obtained after growing L. pneumophilia strain Philadelphia I, serogroup 1, in a liquid culture medium. This cytotoxic activity has been found to differ in its character from that described in earlier works. The dynamics of the accumulation of cytotoxin in the culture medium has been studied, and the work aimed at the determination of the limits of some cultivation parameters, within which the maximum toxin formation is observed, has been carried out.

[The isolation and partial characterization of the cell wall proteins of Listeria monocytogenes]. / Vydelenie i chastichnaia kharakteristika belkov keltochnoi stenki Listeria monocytogenes.

The preparative scheme for the purification of proteins with molecular weights of 39 and 79 kD, obtained from L. monocytogenes membrane fractions, has been developed. This technology included the cultivation of bacteria in heart-brain broth, isolation of bacterial membranes, the extraction of their components with Triton-X-100 and chromatography on Superose columns. The purified proteins have been shown to form structures with a molecular weight of 500-100 kD and pl 4.7 in water solutions.

[The splitting of the acceptor proteins of the protein kinase system in eukaryotic cells by Legionella cytolysin]. / Rasshcheplenie aktseptornykh belkov proteinkhinaznoi sistemy éukarioticheskikh kletok tsitolizinom legionell.

In the process of protein kinase reaction carried out in the mixture consisting of tris-HCl buffer, EDTA, MgCl2, gamma-32P-ATP and the cytoplasmic fraction of rabbit pulmonary cells the phosphorylation of proteins with molecular weights of 150 and 55 kD took place. The addition of L. pneumophila culture fluid to the reaction mixture resulted in the splitting of phosphorylated proteins with the formation of the component having a molecular weight of 45 kD. These disturbances in protein kinase reaction were found to occur due to the involvement of Legionella cytoplasm, a previously characterized protein with a molecular weight of 37 kD, into the process. In this connection, the participation of cytolysin in the pathogenesis of Legionella infection may also be considered from the viewpoint of the effect produced by cytolysin on the regulatory processes affecting the metabolism of target cells.

[The purification and characteristics of listeriolysin O from Listeria monocytogenes]. / Ochistka i kharakteristika listeriolizina O Listeria monocytogenes.

A scheme of the purification of listeriolysin O produced by L. monocytogenes strain NCTC 7973 was developed. The isolation procedure included the cultivation of the bacteria in heart-brain broth, the concentration of culture liquid free of bacteria with ammonium sulfate, cation exchange chromatography on a column packed with CM-Sepharose and Mono S, gel chromatography on a column packed with Superose 12. The preparation obtained with the use of this procedure was homogeneous, as confirmed by the data of SDS electrophoresis. The protein obtained in this investigation was no different from the protein studied earlier in its physico-chemical properties (molecular weight, heat stability, inhibition with thiole-active compositions, cholesterol, sensitivity to proteolytic enzymes) and corresponded to the characteristics of thiole-dependent hemolysins.

[Monoclonal antibodies to Legionella pneumophila cytolysin]. / Monoklonal'nye antitela k tsitolizinu Legionella pneumophila.

The fusion of spleen cells, taken from BALB/c mice immunized with the purified preparation of L. pneumophila cytolysin, with cells Sp2/0 and NP has been carried out. As a result, hybridoma cells producing IgG1, IgG3 and IgM antibodies to this protein have been obtained. All monoclonal antibodies (McAb) thus obtained react with L. pneumophila strain lysates in the precipitation test, while IgG3 and IgM antibodies react with erythrocyte diagnostic agents prepared from the lysate of L. pneumophila cells in the hemagglutination test. In the Western blot assay, McAb react with the 37 KD protein (cytolysin) and a number of other proteins from L. pneumophila cultures and L. pneumophila cell lysate, but do not react with the species-specific protein with a molecular weight of 29 KD, contained in the outer membrane of L. pneumophila, as well as with other species: L. bozemanii, L. dumoffii, L. longbeachae, L. micdadei. The possibility of using these McAb conjugated with FITC and peroxidase for the rapid diagnosis of Legionella infection is shown.

[The immunologic properties of Legionella cytolysin]. / Immunologicheskie svoistva tsitolizina legionell.

Immunogenic properties of cytolysin were studied in experiments on guinea pigs. Preliminary immunization with cytolysin led to the suppression of response to ConA in lymphocytes not adhering to nylon wool and to the stimulation of response to Legionella antigens in lymphocytes adhering to nylon wool. For a month after infection with L. pneumophila the suppression of the proliferative activity of lymphocytes in the spleen of the immunized animals in response to ConA and Legionella antigens was observed, while in the lungs transitory suppression of response to ConA and Legionella antigens was followed by the restoration and then stimulation of proliferation in response to T-cell mitogen and specific antigens. The data obtained in these experiments indicate the capacity of cytolysin for modulating the development of immune response.

[Cytolytic activity of Legionella pneumophila]. / Priroda tsitoliticheskoi aktivnosti Legionella pneumophila.

The properties of cytolysin and metalloproteinase purified by different methods have been studied. The physico-chemical properties of these proteins, including their molecular weight, immunodiffusion patterns, the degree of inhibition by EDTA and diethyl pyrocarbonate, amino acid composition, cytolytic and proteolytic activity, have proved to be similar. We have come to the conclusion that cytolysin and metalloproteinase have similar composition and metalloproteinase activity determines the cytolytic and necrotic activity of the above-mentioned cytolysin.

[The immunogenic and protective properties of the cell wall proteins of Listeria monocytogenes]. / Immunogennye i protektivnye svoistva belkov keltochnoi stenki Listeria monocytogenes.

Two protein antigens with molecular weights of 58 kD (antigen Lm58) and 79/39 kD (antigen Lm79/ 39) were isolated from Listeria monocytogenes cell wall. Only Lm79/39 was shown to protect mice from L. monocytogenes infection, increasing their LD50 and survival time. The protective activity of Lm79/39 correlated (r = 0.64) with its mitogenic properties and its capacity for activating the production of interleukin-1- and interleukin-2-like factors. More over Lm79/ 39 induced more strong than Lm58 specific lymphocyte proliferation. The two antigens had practically no difference in their capacity for cytotoxic cell activation. The protective activity of Lm79/39 is probably linked with its immunomodulating properties, which opens a perspective for its use as a component of an antilisteriosis vaccine.