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Due to the progressive growth of the bacteria caused by the widespread use of antibiotics, treatment of streptococcosis is becoming increasingly difficult. Reliable vaccination against Streptococcus suis is necessary. Modern molecular diagnostic and genetic engineering capabilities create prospects for direct cloning of the protective epitopes of the Lmb gene of the local S. suis strain into the proposed delivery system of the pig immune system antigen. Among oral vaccine carriers, Bacillus subtilis is recognized as a relatively environmentally friendly carrier with an efficient protein secretion system and adaptive metabolism capable of spore production under relatively harsh conditions. This spore property can be used to increase the stability and reusability of vaccines. The possibility of using the protective Lmb epitopes of S. suis in B. subtilis as a carrier of an oral recombinant vaccine against Streptococcus suis was studied. The nucleotide sequences of S. suis were obtained from the GenBank database after a preliminary analysis of literature data on the known protective antigens of S. suis of various serotypes. Nucleotide sequence analysis was performed using Unipro UGENE v. 43.0. The Immune Epitope Database (IEDB) was used to search for T (CTL and Th) and B dependent epitopes of the Lmb gene. A computer-designed vaccine in which localization of CTL, B, and Th epitopes is predicted is described. The results of cloning the sequence of the antigenically active epitope of the S. suis Lmb protein in B. subtilis for subsequent oral administration and study of changes in immunological reactions and adverse reactions in animals are described. The possibility to clone the epitopes of recombinant S. suis Lmb protein into the pBE-S polylinker vector was revealed. In the long term, it seems possible to create a new inexpensive and easy-to-use vaccine against S. suis that does not require injection.

In the Russian Federation, the presence of all serotypes of Salmonella in products is unacceptable. However, the existing ELISA tests are applicable for seromonitoring for the presence of antibodies only to Salmonella of several serotypes. In the article, the authors proposed a system based on the agglutination reaction with a fluorescently labeled antigen - IRA. The purpose of the study is to demonstrate the use of IRA in the example of an analysis of the epizootic situation at one of the poultry farms in Russia and to show an example of the interpretation of the results of serological studies to control bacterial infections in broiler chickens. The peculiarity of the new modification is that in ultraviolet rays the negative reaction of the “button” glows in the form of a dot. The authors studied sera from a herd of broiler chickens affected by Salmonellosis and found antibodies to Salmonella of two serotypes, Infantis and Hamburg. The analysis of seroprevalence to these two Salmonella serotypes made it possible to assess the greater epizootic significance for Hamburg serotype Salmonella. The use of the IRA, incl. based on antigens from bacterial cultures isolated from poultry products, and pathological material, allows for serological diagnosis of bacterial infections of birds concerning the entire variety of bacteria that can be found in a poultry farm, unlike ELISA systems.

Marek’s disease virus is ubiquitous and can harm not only poultry, but also be oncogenic for humans. VBM and malignant tumors induced by them are a convenient and accessible natural model for studying herpesvirus-associated carcinogenesis. To date, according to our observations, there are additional risks of human infection with the Marek’s disease virus - the disease began to appear in broiler chickens 30 days and older, i.e. contact with poultry meat carries a risk of infection. In addition, COVID-19 disease may be accompanied by folic acid deficiency, i.e. a violation of the folate cycle in humans, which increases the risk of manifestation of diseases associated with DNA viruses, since a violation of the folate cycle can reduce the activity of DNA methylation, incl. viral DNA. Methylation is carried out enzymatically in the first minutes after DNA replication, i.e. postreplicatively. Since the DNA nucleotide sequence does not change, methylation is essentially an epigenetic event. We have studied the relationship between the methylation of promoters of the Marek’s disease virus and the copy number of the virus. The assessment of the presence or absence of methylation, as well as partial methylation, was carried out on the basis of identifying the difference between the threshold cycles dC(t). The presence of unmethylated sites included in the studied promoter sequence was detected on the basis of the ability of methylsensitive restrictases AciI and GlaI. A correlation was found between the concentration of genomic DNA of the Marek’s disease virus serotype 1 strain CVI 988 in cell culture and the presence of demethylated CpG islands in the composition of promoters located at position 9413-9865 bp. and 127943 - 128193 b.p. genomic DNA of the virus. The data obtained make it possible to explain the mechanism of the increase in the pathogenicity of herpesvirus infections under conditions of a decrease in the activity of viral DNA methylation in the body.

This work is devoted to an experimental study of the reaction of body tissues to an implant based on bacterial cellulose synthesized by the bacterial strain Gluconacetobacter xylinus. The influence of the internal environment of the body on the characteristics of the implanted material was also studied to determine the prospects for its use in veterinary medicine.Currently, the issue of creating new implantable materials for a long time, or improving existing ones, does not lose its relevance. Based on this, it can be concluded that there are shortcomings in the previously developed materials. Certain requirements are imposed on implantable materials, such as elasticity, strength, porosity, non-toxicity, and others. The most important property of such materials can be called biocompatibility, as well as resistance to the effects of the biological environment.This study is aimed at establishing the possibility of using bacterial cellulose (BC) as an implantable material, which combines all the necessary properties for implants. The study of the reaction of body tissues to the implant was carried out on laboratory rats of the Wistar line. The implanted material was placed on the outer layer of the muscles of the abdominal wall of laboratory animals, after which, on the 14th, 30th and 90th days, a visual examination of the state of cellulose and nearby tissues was carried out, and tissues were selected for histological examination.The experimental results indicate that the implant based on bacterial cellulose does not cause negative reactions from nearby tissues, does not collapse during the observation period, and is reliably fixed on the muscle layer by a capsule of collagen fibers.

The level of expression of anti-inflammatory cytokines NF-kB, IL-6, IFN-y, Caspasa-3, FC in chickens in the lungs and intestines during the modeling of infectious bronchitis in chickens was studied. To simulate coronavirus pneumonia, the vaccine was administered individually, 10 doses per head orally. The chickens of the 1st experimental group were fed with the Lyumantse preparation at the rate of 3 kg / t of feed, the 2nd experimental group received the Glitsevir drug at the rate of 200 μg / 0.3 ml per head. The chickens of the control group did not receive the preparations. It was revealed that antiviral drugs in the experimental groups suppressed the destruction of epithelial cells in the intestine. This may not always be an indication of a positive character, as in the case of apoptosis, not only the intestinal cells affected by the virus particles but also healthy cells are destroyed. There was a decrease in the number of active macrophages in the intestines of the experimental groups relative to the control. The amount of interferon produced was also below the control, which indicates a decreased activity of the immune system. A higher pro-inflammatory activity in the respiratory system of chickens was detected when Glicevir was used. It consists of increased expression of IL-6, interferon-gamma, macrophage receptor to Fc antibody fragments and inflammatory regulatory factor NF-kB genes compared to Lumantse with anti-inflammatory activity, but also compared to untreated control group chickens. It is concluded that it is possible to predict the risk of an exacerbation of an infectious process in the lungs against the background of a local decrease in the viral load in the intestine. An integrated approach is needed in the treatment of coronavirus infections, including either systemic antiviral drugs or anti-inflammatory drugs.

We studied the effect of early accumulation of N-3-oxo-dodecanoyl-homoserine lactone on the suppression of Pseudomonas aeruginosa reproduction, biofilm formation, and elastase activity. N-3-oxo-dodecanoyl-homoserine lactone in various concentrations was added to the P. aeruginosa culture, and changes in the concentration of bacteria and the formation of biofilms were studied in dynamics. N-3-oxo-dodecanoyl-homoserine lactone in a concentration of 25 μM, decelerated proliferation of bacterial cells during the first 6 h of culturing (p

Pseudomonas aeruginosa is a widely represented species of bacteria possessing of a pathogenic potential. This infectious agent is causing wound infections, fibrotic cystitis, fibrosing pneumonia, bacterial sepsis, etc. The microorganism is highly resistant to antiseptics, disinfectants, immune system responses of the body. The responses of a quorum sense of this kind of bacteria ensure the inclusion of many pathogenicity factors. The analysis of the scientific literature made it possible to formulate four questions concerning the role of biofilms for the adaptation of P. aeruginosa to adverse environmental factors: Is another person appears to be predominantly of a source an etiological agent or the source of P. aeruginosa infection in the environment? Does the formation of biofilms influence on the antibiotic resistance? How the antagonistic activity of microorganisms is realized in biofilm form? What is the main function of biofilms in the functioning of bacteria? A hypothesis has been put forward the effect of biofilms on the increase of antibiotic resistance of bacteria and, in particular, P. aeruginosa to be secondary in charcter. It is more likely a biofilmboth to fulfill the function of storing nutrients and provide topical competition in the face of food scarcity. In connection with the incompatibility of the molecular radii of most antibiotics and pores in biofilm, biofilm is doubtful to be capable of performing a barrier function for protecting against antibiotics. However, with respect to antibodies and immunocompetent cells, the barrier function is beyond doubt. The biofilm is more likely to fulfill the function of storing nutrients and providing topical competition in conditions of scarcity of food resources.

The effect of the drug Lumantse on the infectious bronchitis virus of chickens was evaluated. Infectious bronchitis of chickens is a highly contagious disease characterized by damage to the respiratory system and reproductive organs in young animals caused by a virus of the genus Gamma-coronavirus. The condition of the respiratory system caused by the infectious bronchitis virus (IBD) in chickens has much in common with the pathology of the respiratory system caused by SARS-CoV-2 in humans. For broilers, the course of IBD is characterized more often with damage to the respiratory system, manifested by bronchitis, pneumonia, tracheitis, as well as with kidney damage in the case of circulation of nephropathogenic strains. The effectiveness of the virocidal drug Lumantse was tested on 14-day-old cross shawer chickens infected with a ten-fold dose of the Nobilis IB Ma5 vaccine strain against infectious chicken bronchitis. The results of the studies showed that when the immune system is actively stimulated, the inflammatory response increases, with a simultaneous drop in the viral load, which is why a significant percentage of lung inflammation (60%) was observed in the experimental group. Compared with the control group, when using the drug Lumantse, there is a lower number of inflammatory reactions of the lungs, thymus by 40%, as well as the lowest concentration of viral particles in the lungs and intestines.

Infectious bronchitis (IB) of chickens is a highly contagious disease characterized by damage of the respiratory system and reproductive organs in young animals caused by a virus of the genus Gamma coronavirus. The condition of the respiratory system caused by the IB virus in chickens has many similarities with the pathology of the respiratory system caused by SARS-CoV-2 in humans. The effectiveness of virucidal drugs (Argovit, Triviron, Ecocid, and lauric acid monoglyceride) was tested on chickens inoculated with a tenfold dose of a vaccine strain based on the attenuated virus H120 against IB of chickens. On the 6th day after inoculation, inflammatory changes in the intestines, lungs, and thymus were observed in the control group. The experimental groups were characterized by less pronounced inflammatory reactions and a lower proportion of thymus and lung probes containing genomic IB virus RNA. Since the virucidal activity of four orally administrated formulations was possible only in the intestine, the experimental data indirectly confirmed the hypothesis of the possibility of the predominant accumulation of coronaviruses in the intestine and subsequent lung damage due to the hematogenous redistribution of viral particles and IBV antigens. It was suggested that other coronaviruses including SARS-CoV-2 can implement a similar mechanism.

In the course of the study permeability of intestinal mucosa of chickens suffering from eimeriosis while treating them with various veterinary drugs, including probiotics, was evaluated. The simulation of a typical clinical picture of eimeriosis was carried out by oral administration of suspension with coccidial oocysts (1.6 × 105/head) using a probe. To create different forms and different intensity of inflammatory processes, chickens that received various anticoccidial preparations and probiotic strain Bacillus subtilis were infected with eimeria. According to the data from an autopsy, it was found that the use of a spore probiotic based on Bacillus subtilis and anticoccidial drugs containing robenidine hydrochloride and salinomycin had a positive protective effect when treating chickens from eimeriosis. A similar picture was observed when assessing permeability of intestinal mucosa as affected by bacteriophage, whereby permeability decreased with the use of probiotics and the above-mentioned active agents. In general, the decrease in productivity was significant in all groups. However, the effect of spore-based probiotics was quite pronounced against the background of eimeria polyresistance. In the situation where anticoccidial drugs are less effective, the use of a spore-based probiotic can have a noticeable protective effect. The effect of all anticoccidial drugs under study on the concentration of oocysts and the state of the mucosa was insignificant, which indicated polyresistance of different types of eimeria isolated from biological material to these drugs. The analysis of the intestinal mucosa integrity, based on the study of mucosa permeability to bacteriophages and a Johnson and Reid scoring procedure showed that a spore probiotic based on B. subtilis and anticoccidial drugs containing robenidine and salinomycin had the best protective effect against eimeriosis caused by field isolates of eimeria. When treating chickens suffering from eimeriosis caused by polyresistant forms of E. acervulina and E. tenella, it is advisable to use probiotics alongside with drugs based on robenidine and salinomycin.

We studied the effect of early accumulation of N-3-oxo-dodecanoyl-homoserine lactone on the suppression of Pseudomonas aeruginosa reproduction, biofilm formation, and elastase activity. N-3-oxo-dodecanoyl-homoserine lactone in various concentrations was added to the P. aeruginosa culture, and changes in the concentration of bacteria and the formation of biofilms were studied in dynamics. N-3-oxo-dodecanoyl-homoserine lactone in a concentration of 25 μM, decelerated proliferation of bacterial cells during the first 6 h of culturing (p0.05) and stimulated biofilm formation after 18 h of culturing. Elastase activity of P. aeruginosa increased significantly after addition of N-3-oxo-dodecanoyl-homoserine lactone in a concentration of 0.75 μM.

Infectious bronchitis of chickens (IBC) is a widespread disease in the Russian Federation caused by a virus from the genus Gammacoronavirus The pathology of the respiratory system caused by the IBV virus in chickens has many similarities with the pathology of the respiratory system caused by SARS CoV2 in humans The efficacy of the virucidal drugs "Ecocid C", "Triviron", "Argovit" was tested on chickens infected with a tenfold dose of the vaccine based on the attenuated H120 strain against infectious bronchitis of chickens (IBV) In the experiment, the presence of inflammatory changes in the intestines, lungs and thymus was observed on day 6 after infection The experimental groups were characterized by less pronounced inflammatory changes and a lower proportion of thymus and lung probes containing genomic IBV RNA Since the virocidal activity of Trivirone, Ecocide C, Argovit was possible only in the intestine, then as a model of respiratory infection with COVID19, the experimental data indirectly confirm the hypothesis of the fundamental possibility of the predominant accumulation of coronaviruses in the intestine and subsequent lung damage during hematogenous redistribution of viral particles and antigens such as IBV and other coronaviruses, including SARS CoV2 The dynamic balance between the reproduction of coronaviruses in the intestine and their elimination should be easily disturbed when the concentration of functionally active viral particles (under the action ofvirucidal agents) decreases, incl due to the initially low concentration of coronaviruses In terms of pharmacoprophylaxis of infectious bronchitis, it seems promising to use virucidal agents in the period preceding the formation of supply immunity Инфекционный бронхит кур (ИБК) - широко распространенное в Российской Федерации заболевание, вызываемое вирусом из рода Gammacoronavirus Патологии респираторной системы, вызванные вирусом ИБК у кур, имеют много общих черт с патологией респираторной системы вызванной SARS CoV2 у человека Было проведено испытание эффективности вироцидных препаратов "Экоцид С", "Тривирон", "Арговит" на цыплятах, зараженных десятикратной дозой вакцины на основе аттенуированного штамма H120 против инфекционного бронхита кур (IBV) В эксперименте наблюдали наличие воспалительных изменений в кишечнике, легких и тимусе, на 6 день после заражения Экспериментальные группы характеризовались менее выраженными воспалительными изменениями и меньшей удельной долей проб тимуса и легких содержащих геномную РНК IBV Так как вироцидная активность Тривирона, Экоцида С, Арговита была возможно только в кишечнике, то в качестве модели респираторной инфекции COVID19 данные экспериментов косвенно подтверждают гипотезу о принципиальной возможности преимущественного накопления коронавирусов в кишечнике и последующем поражении легких при гематогенном перераспределении вирусных частиц и антигенов как IBV, так и других коронавирусов, включая SARS CoV2

Lactobacillus salivarius belongs to the microbiota of human oral cavity and gastrointestinal tract, as well as of bird and pig intestines. Probiotic activity of various L. salivarius strains has been recently extensively investigated. Production of exopolysaccharides and formation of biofilms as a mechanism providing for resistance to unfavorable factors are also of interest. The goal of this work was to assess the efficiency of microbiological methods for analysis of bacterial concentrations in the cultures of L. salivarius strain NBR2. Samples of lactobacteria grown in liquid medium were collected at equal intervals. The parameters determined were the number of colony-forming units (CFU/mL), share of dead cells by the membrane permeabilization test (LIVE/DEAD) using flow cytometry and fluorescence microscopy, optical density at 595 nm, and pH. After 10 h of cultivation, formation of aggregates commenced, which consisted mainly of living cells and were detected throughout the experiment (30 h). This resulted in underestimation of bacterial abundance determined by plating (CFU/mL). Optical density of the culture and the share of dead cells determined by the LIVE/DEAD method are more reliable criteria of growth of the statically developing L. salivarius culture, which is prone to formation of biofilms and cell aggregates.

There was studied the species composition of the wheat grain microbiota, representatives of which could be potential producers of organic compounds for modern biotechnology. Twenty wheat (Triticum vulgaris) samples were tested, from microbiocenoses of which the strains of heterotrophic microorganisms resistant to toxic concentrations of copper, zinc, manganese and iodine salts were isolated and described. The contents of zinc, manganese and copper salts in a suspension of washed bacterial cells were determined using a highly sensitive multielement analysis method of inductively coupled plasma mass spectrometry (ICP-MS). Using media containing manganese, we isolated and identified Stenotrophomonas maltophilia, Bacillus cereus, Lactococcus lactis, Bacillus subtilis, Brevibacillus sp., Bacillus amyloliquefaciens. Using a medium containing 1% KJ, we isolated Vagococcus sp., Paenibacillus dendritiformis and three unidentified isolates. On a nutrient medium containing copper sulfate, one isolate of an unknown species was grown. In the presence of 1% zinc sulfate, Klebsiella pneumonia, Enterococcus faecalis, Enterococcus faecium, Ralstonia insidiosa, Stenotrophomonas maltophilia have grown that allows using them for the development of selective media. Bacteria of the genus Bacillus have been detected, which are characterized by the ability to accumulate copper compounds to a concentration of 22.3 mg/g dry biomass. The 16S rRNA gene fragment from this culture has the greatest, but incomplete (98%), homology with Bacillus sp. LY (Genbank AY787805). No data on species identity of this Bacillus strain are available in the literature studied that allows us to refer it and isolated strain Cu2 to a new species, which has not previously been described.

The changes in bacterial genetic material under the action of different biocidal products have been investigated. It was confirmed by PCR and genetic engineering that biocidal product Ecocid was able to remove both chromosomal and plasmid DNA, either isolated or contained within the bacterial cells. Using a disinfectant that destroys DNA on the surfaces of meat production equipment is a promising measure to prevent horizontal transfer of unwanted genetic material, such as bacterial genes associated with the resistance to antibiotics, or genes of toxin production.

We propose an original methodological approach to discrimination of newly isolated Salmonella enterica strains with the use of Dienes test. Dienes test is used for identification of P. vulgaris and P. mirabilis strains. It consists in growth suppression by mobile bacterial strain cultures and the formation of a demarcation line (Dienes line) between the strains growing towards each other. Similarities and differences between salmonella phagotyping method and Dienes test-based discrimination of the strains are detected. The studied sample of salmonellas was divided into 12 phagotypes. Cluster analysis has shown that most of the salmonella strains could not be clusterized by both methods. Discrimination by different methods has shown that the largest clusters contain the same strains. Clusterization of salmonella strains by different methods shows moderate congruency. Rand index used for comparison of the results of the sample clusterization by different methods is 0.88. High heterogeneity of salmonella strains is presumably explained by heterogeneity of antagonism factors within the S. enterica species. Intraspecies antagonism is essential for limitation of the horizontal gene transfer in closely related strains and for increase of the genetic heterogeneity of salmonella population in the host.

Strain parameters of Salmonellas and Lactobacteria affecting their antagonistic activity were studied using an original method. Real-time PCR was applied for measuring the decrease in the concentration of field isolates of Salmonellas isolated from chickens in the presence of field isolates of Lactobacteria also isolated from the gastrointestinal tract of chickens and broiler chickens. Dispersion analysis showed that the probability of suppression of Salmonella growth by Lactobacteria is determined by strain parameters of both Lactobacteria and Salmonellas (p