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V I Levenson

Publications and source records attributed to V I Levenson.

At least 19 recordsLinked to original sources
PubMed1991

Protective ribosomal preparation from Shigella sonnei as a parenteral candidate vaccine.

A parenteral Shigella ribosomal vaccine (SRV) was investigated in animals for safety, antibody-inducing capacity, and protective activity. Ribosomal preparations from a Shigella sonnei phase I avirulent strain were obtained and shown to possess chemical, sedimentation, and other properties typical of bacterial ribosomes. No endotoxin contamination was revealed by a ketodeoxyoctonate assay, although the presence of some kind of O antigen was evidenced by serological findings and the high activity of SRV in inducing the O-antibody response and immunological memory in animals. SRV was nontoxic in mice, guinea pigs, and monkeys and induced no local reactions when injected subcutaneously in reasonable doses. Significant protection against a local Shigella infection (Sereny test) was seen in guinea pigs injected with SRV (efficiency index, about 60%) and the specificity of the protection was evident from cross-challenge experiments. The protective efficiency of SRV was especially high in rhesus monkeys challenged orally with virulent Shigella cells (89%, as calculated from the summarized data of several experiments in 71 animals). Protection in monkeys was long lasting and could be demonstrated several months after injection of SRV. An inexpensive technique can be used for the production of SRV on a large scale. The high immunogenicity of SRV is discussed in terms of the amplifying effect of the ribosome, which serves as a delivery system for polysaccharide O antigen. Further study of SRV as a candidate vaccine for humans seems justified by the data obtained.

Animals↗
PubMed1991

[The immunogenic and serological properties of the O-specific polysaccharide (L-hapten) in Shigella].

O-specific polysaccharide (L-hapten) was isolated earlier (Zh. mikrobiol. epidemiol. immunobiol., 1989, No. 11, pp. 8-11). In this paper L-hapten was shown to be unable, even at high concentrations (up to 2,000 micrograms/ml), to sensitize sheep red blood cells for passive hemagglutination by O-antibodies. At the same time classical LPS and heat-activated LPS were active at concentrations ot 32 and 8 micrograms/ml respectively. The O-antibody-neutralizing activity of L-hapten was lower than that of LPS 10(3)-10(4) times in the passive hemagglutination test and 25-50 times in competitive ELISA. The immunogenicity of isolated L-hapten was very weak: primary response in mice to the i.v. injection of 1-10 micrograms of L-hapten was similar to the effect produced by 10(-3)-10(-4) micrograms of LPS. No protective activity of L-hapten was noted in mice when the challenge dose of virulent shigellae was 16 LD50 or more, and only a weak protective effect was observed with a low challenge dose (8 LD50). The molecular basis of low serological and biological activity of L-hapten is discussed. The most probable explanation of the results obtained in this study is that L-hapten contains some nonspecific carbohydrates, inserted in or complexed with the O-side chain. Despite its low immunogenicity, L-hapten can be an important component of effective bacterial vaccines provided it is included into a suitable delivery system as is the case with Shigella ribosomal vaccine.

Animals↗
PubMed1991

[The immunogenic properties of the endotoxin protein: serum antibodies in animals and man].

Endotoxin protein or lipid A-associated protein (LAP) from Shigella sonnei was isolated and characterized earlier (Zh. mikrobiol. epidemiol. immunobiol., 1991, No. 4, pp. 47-50). In this investigation serum antibodies against LAP were studied in ELISA Anti-LAP antibodies were detected in high titers in the sera of nonimmunized mice, guinea pigs, rabbits, monkeys and healthy adults. We suppose that normal anti-LAP antibodies resulted from interaction between the immune system and environmental endotoxin. Parenteral injections of LAP to different animals induced intensive antibody response with a 100- to 1000-fold increase in the serum anti-LAP antibody level and a significant rise in the serum O-antibody level. The latter is seemingly due to the contamination of LAP with minute amounts of O-antigen (0.12% or less) and to the amplification of its immunogenicity by LAP. Both antigenic and amplifying activity of LAP was destroyed by proteinase K. The biological function of LAP and its possible use as a component of bacterial vaccines are briefly discussed.

Animals↗
PubMed1991

[Shigella endotoxin protein--its isolation and physicochemical characteristics].

The scheme of the isolation of endotoxic protein from S. sonnei 9090 is presented. The isolation procedure includes the 10-minute hot (at 68 degrees C) extraction of protein from endotoxin with 45% aqueous phenol, the precipitation of protein from phenolic extract with 9.5 volumes of 95% ethanol, the purification of protein from lipid material and pigments by multiple extraction with the mixture of chloroform and ethanol in the proportion 2:1 by volume. The yield of protein obtained with the use of this isolation scheme is about 3% of the initial endotoxin preparation. Protein preparations obtained in accordance with this scheme contain 92-95% of protein (determined by Lowry's method), 2.3-3.0% of saccharides (determined by the phenol-sulfate method) and 0.02% of hexose amine, its presence indicating that the preparations contain lipid A (or its fragments) which is firmly bound with endotoxic protein and cannot be extracted with chloroform. As shown in the passive hemagglutination inhibition test, the content of endotoxin in the preparations is less than 0.003%. Out of 7-11 bands revealed by electrophoresis in 15% polyacrylamide gel in the presence of sodium dodecyl sulfate, 3 main bands have molecular weights of 43, 38 and 18 KD. Three antigens differing in their electrophoretic mobility and diffusion rate in 1% agarose gel can be detected in the preparations by the method of immunoelectrophoresis with the use of antisera to both endotoxin and endotoxic protein.

Bacterial Proteins↗
PubMed1991

[Shigella endotoxin protein--its electrophoretic and serological properties].

The electrophoretic analysis of lipid A-associated protein (LAP), obtained from S. sonnei, in polyacrylamide gel in the presence of sodium dodecyl sulfate and urea has revealed the heterogeneity of the preparation; it has found to contain three main components with molecular weights of 43, 38 and 18 KD and some minor components with molecular weights of 49, 45 35, 30, 29, 27, 5, 21 and 14 KD. The electrophoretic mobility of the main protein components in the isolated preparation of LAP coincides with that of endotoxin components. The dissociation of proteins and lipopolysaccharide in the process of boiling the endotoxin in 2% sodium dodecyl sulfate is indicative of the noncovalent binding of these components. LAP contained in the endotoxin, in contrast to isolated LAP, is resistant to trypsin and proteinase K. The enzyme immunoassay (EIA) system with the use of LAP as a component of its solid phase has been developed, which makes it possible to carry out the quantitative determination of antibodies to this protein. The EIA system shows high sensitivity in the determination of anti-LAP IgG antibodies: in hyperimmune rabbit sera their titer is 1:250,000-1:800,000. As shown by the method of competitive EIA, the antigenic affinity of LAP of different origin corresponds to the degree of taxonomic propinquity of microorganisms: the maximal degree of cross reactions is observed between LAP obtained from S. sonnei, S. flexneri and Escherichia coli, while their affinity to Salmonella typhi is considerably less; remote microbial species (Bacterium bifidum and Sarcina marcescens) give practically no cross reactions.

Animals↗
PubMed1991

[The action of ribosomal preparations on nonspecific resistance to bacterial infection and on early tolerance to endotoxic shock].

Ribosomal preparations from Shigella flexneri and Shigella sonnei, introduced parenterally into mice, enhance their resistance to infection with the causative agents of typhoid fever and staphylococci. This effect is considerably less pronounced than that produced by the preparation of homologous lipopolysaccharide isolated by Boivin's method. After the administration of ribosomes nonspecific resistance to bacterial infective agents lasts for a short time. Ribosomal preparations do not enhance the resistance of mice to the lethal action of endotoxin.

Animals↗
PubMed1991

[The determination in saliva of IgA antibodies to Shigella ribosomes for the diagnosis of dysentery].

The levels of antiribosomal antibodies to Shigella ribosomes in serum and saliva samples from 38 dysentery patients (15 S. sonnei cases and 23 S. flexneri cases), 14 patients with salmonellosis and 136 healthy adults were determined in ELISA with ribosomes from S. sonnei R-mutant used as solid-phase antigen. High levels of "normal" antiribosomal IgA, IgG and IgM antibodies were revealed in the sera of healthy persons while the level of salivary IgA antibodies was very low. In dysentery infection no increase in the levels of serum IgG and IgM antibodies and only a slight increase in the level of IgA antibodies were revealed. Local immune response was manifested by the early (on days 2-4 from the onset of infection) and significant augmentation (12- to 16-fold) of salivary antiribosomal IgA antibodies. An increase in the level of these antibodies was registered in 95-100% of dysentery patients but not in patients with salmonellosis, which made it possible to recommend the method for diagnosing shigellosis. Immune response to Shigella ribosomal antigens, in contrast to the response induced by Shigella O-antigen, is almost exclusively local.

Acute Disease↗
PubMed1991

[The protective properties of the endotoxin protein].

The isolation and properties of endotoxin protein, or lipid A-associated protein (LAP), from Shigella sonnei were described earlier (Zh. mikrobiol. epidemiol. immunobiol., 1991, No. 4, pp. 11-17, and No. 7). In this report the data on its protective activity are presented. In experiments on mice one nanogram of LAP injected i. v. protected 50% of the animals against i. p. challenge with 40 LD50 of virulent S. sonnei. Guinea pigs injected s. c. with 10 micrograms of LAP were protected against local (keratoconjunctival) challenge with S. sonnei, the efficiency of immunization being 58%. LAP preparations containing no detectable amounts of O-antigen (less than 0.003%) were found to have a protective effect. Hyperimmune anti-LAP rabbit serum prevented local infection when incubated with S. sonnei challenge inoculum before injection into guinea pigs. Both active and passive protection induced by LAP was specific since no effect was observed in animals challenged with Shigella flexneri. In the homologous system the protective effect of anti-LAP serum was abolished by the addition of protein-free LPS. These results are compatible with the hypothesis that the protective activity of LAP depends on the presence of minute amounts of O-antigen whose immunogenic effect is greatly amplified by the protein component of the natural endotoxin complex.

Animals↗
PubMed1990

Protective milk O antibodies induced in guinea pigs by parenteral Shigella ribosomal vaccine.

IgG and IgA O antibodies were studied in milk and sera of guinea pigs subcutaneously immunized at various stages of pregnancy with Shigella ribosomal vaccines (SRV) from Shigella sonnei and Shigella flexneri. Both vaccines induced O antibodies in milk, the level of IgA antibodies being significantly higher than that of IgG antibodies. The immune milk provided a clear-cut protection against experimental Shigella-induced keratoconjunctivitis. These results are consistent with the previously shown ability of parenteral SRV to stimulate gut-associated lymphoid tissue and confirm the involvement of secretory IgA O antibodies in the protection induced by the parenteral SRV. The high level of milk antibodies in vaccinated guinea pigs suggests the possibility to use the parenteral SRV for developing lactogenic immunity.

Animals↗
PubMed1990

[The molecular heterogeneity of Shigella sonnei lipopolysaccharide based on polyacrylamide gel electrophoretic data].

The molecular heterogeneity of S. sonnei lipopolysaccharide (LPS), reflecting the size of lateral O-specific polysaccharide chains, has been established by the method of electrophoresis in acrylamide gel in the presence of sodium dodecyl sulfate and urea. The dominating components fall into three types, viz. those with 0-3, 10-16 and 35-40 repeating structures, the remaining components being minor ones. The electrophoretic profile of S. sonnei LPS considerably differs from the profiles of Escherichia coli and S. flexneri LPS, but coincides with the LPS profiles of other strains with different virulence. The preparations of LPS obtained by extraction with trichloroacetic acid have the same electrophoretic profiles as LPS obtained by the method of aqueous phenol extraction. The domination of certain molecular variants reflects, seemingly, specific features of the biosynthesis of LPS, characteristic of a given strain. The mechanisms of the preferable synthesis of lateral O-specific chains of the definite size and the importance of the molecular parameters of lateral chains for the biological properties of LPS require further study.

Electrophoresis, Polyacrylamide Gel↗
PubMed1988

Parenteral immunization with Shigella ribosomal vaccine elicits local IgA response and primes for mucosal memory.

The parenteral Shigella ribosomal vaccine (SRV), which previously was shown to protect guinea pigs and monkeys, has been compared with lypopolysaccharide (LPS) for its ability to induce a systemic and a local immune response. Injection of SRV caused a significant rise of the serum O antibodies of different classes and the appearance of IgA O antibodies in tears of guinea pigs and saliva and bile of monkeys. In guinea pigs, the local IgA response to parenteral SRV was much more intensive than that to feeding of high doses of LPS, while in monkeys it was nearly as high as that to challenge with a high dose of live pathogen. These data provide an immunological basis for the protective effect of SRV and are in disagreement with the widely accepted view of the inefficiency of parenteral antigens in stimulating mucosal immunity. The results are interpreted from the viewpoint of the role of ribosomes as a delivery system for the Shigella O antigen which provides high potency of SRV in stimulating local lymphoid tissue and makes it a good vaccine candidate.

Administration, Oral↗
PubMed1988

[Specificity of the protective action of a ribosomal Shigella vaccine and the absence of activity in the ribosomes from R mutants].

The ribosomal preparations of S. sonnei and some other bacterial species were obtained by the method of differential centrifugation, and the specificity of their protective action was studied in the keratoconjunctivitis test on guinea pigs. The ribosomal preparations were introduced parenterally in a single injection, and their protective action was determined two weeks later by the challenge of the animals with S. sonnei virulent strain and the subsequent calculation of the efficiency index (EI) by the formula: EI = C-V/C X 100, where C and V are the percentage of resistant eyes in the control and vaccinated groups of the animals respectively. For the ribosomal preparation obtained from a homologous avirulent strain this index was equal to 58%, while for the heterologous ribosomes obtained from Escherichia coli, Salmonella minnesota and S. flexneri in was close to zero. The ribosomal preparations obtained from S. sonnei R-strain which had no surface or cytoplasmic O-antigen also proved to be ineffective in rendering protection against local Shigella infection. The results of this investigation are compared with the data obtained by other authors, and the analysis of these results leads to the conclusion that the O-specific component is the indispensable factor of the protective activity of many ribosomal vaccines and its molecular properties require further study. The possible role of other components of the ribosomal vaccine is also discussed.

Animals↗
PubMed1988

[A protective factor of ribosomal shigellosis vaccine].

Shigella ribosomal vaccine was shown previously to possess protective properties in the keratoconjunctival test on guinea pigs and to be capable of preventing experimental infection in 90% of challenged monkeys. The presence of the O-specific component (OSC) constituting about 0.5% of the ribosomal preparation by serological activity suggested its importance for the protective effect. This was studied in experiments with two O-specific immunosorbents prepared by coupling anti-O rabbit antibodies with Staphylococcus aureus cells or with CNBr-Sepharose. Ribosomes treated with immunosorbents proved to be lacking the serologically active OSC and lost their ability to induce O-antibody response in rabbits and mice. After the removal of this component ribosomal preparations were incapable of ensuring protection from Shigella kerato-conjunctival infection. The isolated OSC was also inactive in this test. The data obtained in this investigation confirm the hypothesis stating that the protective activity of Shigella ribosomal vaccine is based on the combined action of ribosomes and O-specific factor whose nature and properties require further study.

Animals↗
PubMed1988

[Isotypic characteristics of serum and secretory O antibodies and local immunological memory in the parenteral immunization of guinea pigs with a ribosomal Shigella vaccine].

Guinea pigs were immunized subcutaneously with ribosomal vaccine prepared from S. sonnei and their systemic and local humoral response was studied by means of ELISA techniques with the use of monospecific antisera to guinea pig IgA and IgG. Injection of the ribosomal vaccine leads to a significant rise in the levels of IgA O-antibodies in tears, IgG and IgA O-antibodies in the serum. The presence of IgA O-antibodies in tears was seemingly the result of their local synthesis rather than the seepage of serum IgA. The stimulation of the local and systemic anti-O response was more pronounced after parenteral immunization with the ribosomal vaccine than after immunization with the corresponding dose of lipopolysaccharide (LPS). Parenteral immunization with the ribosomal vaccine induced the development of both systemic and local memory. The priming effect produced by relatively small doses of this vaccine (40 micrograms), administered parenterally, was similar to the effect of prolonged and intensive stimulation ensured by 10-day feeding with LPS (the total dose being 5,000 micrograms).

Animals↗
PubMed1988

[Structure of the mucous membrane of the distal part of the large intestine in the monkey].

By means of histological, histochemical, immunohistochemical and morphometrical methods, according to 24 objective morphological parameters, bioptates of endoscopically unchanged mucosal membrane of the large intestine, obtained from 22 clinically healthy macaque rhesus males, have been studied. The data on vital structure and cellular interconnections in the mucous membrane of the distal part of the large intestine have been received. The data can be used for estimating certain pathological processes, when modelling the large intestine diseases in monkeys.

Animals↗
PubMed1986

[Delayed-type hypersensitivity in mice immunized with ribosomal vaccines against Shigella sonnei].

The capacity of S. sonnei ribosomal vaccine (SRV) for inducing delayed hypersensitivity (DH) was studied in the foot pad test on mice. The test injection of SRV in a dose of 10 micrograms, inducing only transient changes in intact mice, led to a highly pronounced reaction in mice immunized with ribosomes in Freund's complete adjuvant. The mean difference in thickness between the test and control (injected with physiological saline) feet amounted to 0.54 mm on day 16 after immunization in two injections. Immunization in a single injection produced a less pronounced reaction. After the injection of SRV without the adjuvant no DH developed in the animals. Histologically, the reaction was typical for DH in mice: in 24 hours, at the time of maximal swelling, the cell infiltration of the tissues with the prevalence of mononuclear cells and a significant proportion of neutrophils was observed. The specificity of this reaction was confirmed by cross tests in mice immunized with SRV and bovine serum albumin: positive reactions were observed in homologous systems only. The independence of the foot pad reaction to SRV from antibody formation was corroborated by the fact that the peak of humoral response occurred two weeks before the development of cutaneous hyperreactivity. It was also shown that, in contrast to antibody formation, the foot pad reaction was completely resistant to the treatment of mice with cyclophosphamide in a dose of 200 mg/kg.

Animals↗
PubMed1985

[Local immunity in the parenteral immunization of guinea pigs with a ribosomal dysentery vaccine].

After immunization of guinea pigs with Shigella sonnei ribosomal vaccine O-antibodies appeared not only in the blood serum of the animals, but also in their lacrimal fluid. Since no correlation between the levels of serum and secretory antibodies was detected and since the time course of changes in these antibody levels was quite different (serum antibodies reached their peak on day 7 while secretory antibodies, on day 14 after vaccination), antibodies in lacrimal fluid were supposed to reflect local immune response induced by parenteral administration of ribosomal vaccine, irrespective of systemic immune response. The peak of secretory O-antibodies coincided in time with the period of the highest protection of guinea pigs from Shigella keratoconjunctivitis. The animals with a high level of secretory antibodies were better protected from Shigella infection than those with a low level of secretory antibodies. These data suggest that locally produced O-antibodies play an important role in protective immunity induced by parenteral administration of the ribosomal vaccine.

Animals↗