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M I Levi

Publications and source records attributed to M I Levi.

At least 37 records · Page 2Linked to original sources
PubMed1987

[Serological reaction systems using enzyme-labelled immunospecific reagents].

Different serological test systems, based on the use of enzyme-labeled immunospecific reagents and intended for testing the material under study for the presence of Yersinia pestis capsular antigen and antibodies to it, are described. Comparative data on the evaluation of their sensitivity to the antigen and antibodies to it in different schemes of enzyme immunoassays (EIA) are presented. As shown in this investigation, EIA systems for the detection of the antigen and antibodies to it can comprise, at the minimum, the following set of reagents: monoclonal antibodies to the capsular antigen, staphylococcal protein A, and the conjugates of the capsular antigen and monoclonal antibodies with horse-radish peroxidase. The authors have come to the conclusion that the use of the serological test systems can essentially increase the reliability of the assay of any individual sample by EIA techniques.

Animals↗
PubMed1986

[Use of immunospecific components labelled with beta-lactamase and horseradish peroxidase for immunoenzyme analysis].

A system for enzyme immunoassay with the use of beta-lactamase as an enzyme marker is described. Similar sensitivity of the enzyme immunoassays with the use of beta-lactamase and horse-raddish peroxidase as enzyme markers was shown. The data on decrease of the antigen binding capacity of the antibodies in the conjugates with beta-lactamase are presented. It is suggested that such a decrease may be associated with glutaric dialdehyde conjugation. The use of the schemes for enzyme immunoassay with simultaneous application of two independently recorded enzymes i. e. horse-raddish peroxidase and beta-lactamase provided confirmation of univalency of the conjugate of the melted capsular antigen of the plague causative agent with beta-lactamase. Identity of the antigenic determinants of the melted antigen and capsular antigen of the plague microbe was demonstrated.

Animals↗
PubMed1986

[Mathematical modelling of the interaction of the plague capsular antigen with antibodies of varying affinity].

The group of high affinity antibodies is advantageous in antigen binding because of different dissociation rates of the antigen-antibody complexes. An antigen interacts with such a group in accordance with the value of the parameters characterizing the group and the antigen. The unbound antigen interacts with the subsequent group by the affinity value and so on. This is the basis of the presented model of univalent antigen interaction with antibodies of different affinity. The model values of the concentration of the bound and free antigens were close to the experimental ones for hyperimmune antiplague horse serum and monoclonal antibodies. The correspondence of the model values to the experimental ones is in favour of the suggested explanation of antigen interaction with antibodies of different affinity. It is advisable that the results be taken into account in estimation of biotechnological possibilities of the preparation of high affinity antibodies.

Animals↗
PubMed1985

[Results of a trial of a plague monoclonal antibody erythrocyte diagnostic agent].

Plague antibody monoclonal erythrocyte diagnosticum was studied in serological tests simultaneously with commercial plague antibody erythrocyte diagnosticum prepared on the basis of hyperimmune horse serum and with commercial plague antigenic erythrocyte diagnosticum. In this investigation the suspensions of numerous strains of Yersinia pestis, other closely related and heterologous organisms, experimentally infected wild and laboratory animals, as well as samples of materials obtained from small rodents caught in several natural foci of plague, were studied. The monoclonal diagnosticum was, practically, not inferior to the similar commercial preparation with respect to the frequency of positive results and the activity of the materials under study in serological tests, but showed greater specificity, as it reacted strictly with Y. pestis capsular antigen.

Animals↗
PubMed1985

[Heterogeneity of monoclonal antibody affinity].

In experiments with Pasteurella pestis monovalent capsular antigen and hybridoma monoclonal antibodies obtained after cloning and recloning the heterogeneity of the active centers of antibodies with respect to their affinity was revealed. In ascitic fluids obtained from the animals inoculated with different hybridoma clones 5 groups of antibodies, differing in their affinity, were determined in each fluid sample.

Animals↗
PubMed1985

[Results of the comparative use of virological and bacteriological control of routine disinfection in maternity homes].

Bacterial viruses were often detected in washings from different environmental objects; not infrequently, the inoculation of washings from the same objects resulted in the growth of Escherichia coli. The expediency of making parallel tests of washings from these objects for the presence of wild strains of bacterial and viral cultures both during the control of disinfection measures and the determination of the effectiveness of disinfection agents is shown.

Bacteria↗
PubMed1985

[Use of monoclonal antibodies for the production of a plague antibody erythrocyte diagnostic agent].

Monoclonal antibodies to Yersinia pestis capsular antigen were fixed onto the surface of formulated sheep red blood cells. The preparation thus obtained was compared with commercial antibody erythrocyte diagnosticum in the passive hemagglutination test aimed at the search for the capsular antigen in the suspensions of Yersinia pestis museum cultures and in the antigen neutralization test aimed at the search for antibodies in the sera of wild and laboratory animals having had plague. Monoclonal erythrocyte diagnosticum proved to be suitable for the detection of both the capsular antigen and antibodies. The comparison of the results of the passive hemagglutination test and the enzyme immunoassay demonstrated the presence of very close relationship between them.

Animals↗
PubMed1985

[Use of beta-lactamase from Bacillus licheniformis 749/C for solid-phase immunoenzyme analysis].

beta-Lactamase from Bacillus licheniformis 749/c was used as a marker for ELISA. Conjugates of the beta-lactamase with the capsule antigen of the plague causative agent and with the monoclonal antibodies to it were prepared by glutaric aldehyde "linking". The conjugates preserved high immunospecific and beta-lactamase activity. High sensitivity of the modification of ELISA allowed detecting up to 8 ng/ml of the capsule antigen of the plague causative agent. The enzymatic activity of the beta-lactamase was determined microiodometrically which provided visual recording of the results of ELISA.

Antibodies, Monoclonal↗
PubMed1984

[Use of monoclonal antibodies in immunoenzyme analysis for demonstrating antigenic monovalency].

To prove the monovalence of the antigen a method has been developed consisting of ELISA with the use of monoclonal antibodies in combination with the antibody neutralization test. Yersinia pestis capsular antigen was disintegrated by heating at 100 degrees C for a short time and subsequently passed through a column packed with Sephadex G-50. The portions of the eluate, showing high activity in the antibody neutralization test and low activity in ELISA (the double antibody sandwich scheme), contained mainly the monovalent antigen. This antigen was replaced by the polyvalent antigen from the antibody complex, but if such complex had been previously fixed by treatment with glutaraldehyde, no replacement of the monovalent antigen by the polyvalent one occurred.

Animals↗
PubMed1983

[Analysis of the discrete structure of antibodies by affinity and antigen-binding capacity].

Immune sera are a mixture of different groups of antibodies belonging to the same class of immunoglobulins, but differing in their affinity. The graphic analysis and numerical methods permit the determination of the size and affinity of each group of antibodies. Differences in affinity are manifested as differences in antigen-binding capacity. The antigen-binding capacity index, calculated as the product of the association constant multiplied by the concentration of the active centers of antibodies, is proposed.

Animals↗
PubMed1983

[Discrete nature of the antibody affinity of immune sera and the importance of this factor for antigen binding].

After mixing an antibody immunosorbent with Pasteurella pestis monovalent capsular antigen the concentration of the antigen in the free and bound states was evaluated. In this study the test points on the graph were found to be located on the lines characterizing different groups of antibodies differing in their affinity. The verification of the discrete structure of antibody affinity in 10 lots of hyperimmune horse serum showed the truth of this suggestion. The analysis of the role played by different groups of antibodies in binding the antigen indicated the prevailing role of a high-affinity group, especially in the zone with the excess of antibodies.

Animals↗
PubMed1982

[Determination of antibody affinity by using antigenic and antibody immunosorbents].

To determine the affinity of the active centers of antibodies, cellulose immunosorbents for antibodies and antigens have been used. The fixation of serum proteins on the sorbent, the interaction of fixed antibodies with a monovalent antigen and the graphic analysis of the results thus obtained allows one to assess not only the concentration of the effective active centers on the sorbent, but also all known characteristics of antibody affinity: the average association constant K0, the common association constant Kt, the geometric association constant Kg, the average association constants which determine the affinity of different antibody groups. The use of antigenic immunosorbent permits one to determine the value of the average internal association constant K0. The determination of antibody affinity in hyperimmune antiplague sera by means of immunosorbents and red blood cells coated with capsular antigen has resulted in obtaining similar values of affinity indices.

Antibody Affinity↗