The review presents data on the antigenic structure and the current classification of epidemically significant serovariants of Listeria. Description of species-specific properties of serovariants of Listeria, which may be common for two or more species, and common antigens with staphylococci and typhoid and paratyphoid bacteria, are given. It has been shown that only the antigenic scheme of Listeria monocytogenes is of practical interest for medical microbiology. Importance of serotyping in the epidemiological analysis to determine the source of infections and ways of its spreading has been determined. Differences in the designation of serovariants in the diagnosis of listeriosis in medical practice are observed. High level of adaptive properties of Listeria, its ability to reproduce in an abiotic environment, including food, susceptibility of immunodeficient individuals, prevalence of food pathway of infection pose a significant danger of increased sickness rate with listeriosis. Serological diagnostics of Listeria has not been developed in detail, and the existing serological methods are aimed at identifying specific antibodies to listeria. Advantages of the serological method include: quick results and the possibility to study any biological material. Currently available serological methods have a number of disadvantages: low reliability of results and low specificity of the study. The most promising method for identification of a serological group of cultures, according to the world classification, is the multiplex PCR method, based on the correlation between the serogroup of an isolate and the presence of specific open reading frames in its genome.

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Currently, one of the topical areas of research is the development of new antigen preparations for the specific diagnosis and prevention of brucellosis, since indication of the pathogen and prevention of the disease is complicated by the ability of brucella to dissociate, and live vaccines used for specific prevention of brucellosis have residual virulence. Thermal extracts (TE) obtained from Brucella abortus I-206 in the L- and S-form can be used as such promising antigens. It is known that TE in the L- and S-forms have immunogenic properties, as well as a modulating effect on the proliferation of immunocompetent cells, morphological changes in the immunocompetent organs of experimental animals.The aimof the work is to study the effect of Brucella abortus thermal extracts in L- and S-forms on the functional state of the cells of experimental animals.Materials  and  methods. The  study  was  performed  on  100  certified  white  mice.  As  objects  of  study,  we  used  the B. abortus I-206 TE in L- and S-forms. Evaluation of the effect of antigenic drugs on the functional state of phagocytes of laboratory animals in vitro was performed on peritoneal macrophages. The total activity of the respiratory chain enzymes in the NBT-test and superoxide dismutase was determined. Cells of intact animals served as controls. As a positive control, a commercial antigenic LPS preparation Escherichia coli was used. The content of cyclic nucleotides in homogenates of immunocompetent organs was determined using ELISA.Results.This study presents materials on the study of the effect of TE on the bactericidal activity of phagocytes and the level of cyclic nucleotides in immunocompetent organs. It has been established that TEs activate oxygen-dependent bactericidal systems of phagocytes. When studying the effect of TE on the content of cyclic nucleotides in immunocompetent organs of white mice, an increase in their concentration was revealed, indicating an increase in the functional activity of the cells.Conclusion.The obtained data make it possible to substantiate the need for a further detailed study of the immunogenic properties of B. abortus TE in the L- or S-form on the organism of experimental animals.

Listeriosis is a saprozoonotic natural anthropurgic infectious disease caused by Listeria monocytogenes, with multiple pathways and factors of its transmission, characterized by pronounced clinical polymorphism from carriage and subclinical to severe generalized forms, meningitis and meningoencephalitis, and high mortality among newborn children and individuals with immunodeficiency. Express diagnostics of listeriosis is based on the use of immuno-chemical (immunodiffusion reaction, enzyme immunoassay) and molecular genetic (polymerase chain reaction) methods. In the practice of laboratory diagnostics, serological methods for the study of listeriosis remain in high demand for verifying the clinical diagnosis. One of the specific, reliable and available serological methods for laboratory diagnostics of causative agents of infectious diseases remains the agglutination test (AT), to conduct which, listeria agglutinating serum is required. Obtaining diagnostic agglutinating listeria serum with a high level of diagnostic sensitivity and specificity will allow timely identification of the pathogen in the test tube AT and on glass, based on the specific interaction of the antigen with the anti-body, with the formation of agglutinate visible to the naked eye. In this study a scheme has been developed for immunization of animal producers to obtain diagnostic listeria agglutinat-ing serum. Evaluation of the clinical efficiency of two series of the serum was carried out based on the indices of diagnostic sensitivity with different serovariants of L. monocytogenes and diagnostic specificity with closely related and heterologous strains in the test tube AT and on glass. During the study of 25 strains of L. monocytogenes serogroups I and II (serotypes 1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4a, 4b, 4c, 7) isolated on the territory of the Russian Federation from various sources (clinical material, food products, wastewater), the serum titer did not differ and amounted to 1:800 in the course of in vitro agglutination reaction; a positive result was obtained on glass in 100% of cases. The assessment of the statistical reliability of the ob-tained test results was at least 89 % with a statistical significance of 95 %, which indicates a high diagnostic efficiency of the serum. In order to establish intra-stage convergence and inter-series reproducibility of studies, two probabilities of binomial distributions were compared. The convergence of staged studies for all positive samples has been proven. Based on the re-sults obtained, listeriosis serum can be used as a medical preparation for in vitro diagnostics of the causative agent of listeriosis.