Vol 98, No 1 (2021)

Introduction. The coronavirus disease (COVID-19) pandemic was announced by WHO in February 2020. In the Khabarovsk Krai, the first three cases of the disease were diagnosed on March 19, 2020, these cases were imported from Argentina (transit through Italy). The epidemic process of COVID-19 in the Khabarovsk Krai is characterized by a slow increase in the incidence. During the period of time when the SARS-CoV-2 seroprevalence study was conducted the incidence rates varied from 35.9 to 39.1 per 100 thousand population. Within the next 5 weeks the incidence continued to increase, the maximum level was 67.3 per 100 thousand population. A statistically significant decrease in the incidence is noted in the first decade of August. The study of the SARS-CoV-2 seroprevalence among residents of the region was carried out from June 9 to June 21, 2020 during the period of increasing intensity of the epidemic process of COVID-19 infection.
Aim. To determine the level and structure of herd immunity to SARS-CoV-2 virus among the population of the Khabarovsk Krai during the period of intensive spread of COVID-19.
Materials and methods. The study was conducted as a part of the first stage of a large-scale Rospotrebnadzor project to assess the herd immunity to SARS-CoV-2 virus among the population of the Russian Federation, taking into consideration the protocol recommended by WHO. The selection of volunteers for the study was carried out by the method of questionnaires and randomization by random sampling. The results of a survey of 2675 individuals were included into analysis. The number of volunteers in all age groups was similar.
Results. The results of the study showed that the herd immunity to SARS-CoV-2 in the total population of the Khabarovsk Krai was 19.6%. The maximum level of herd immunity was observed in children 14–17 years old (34.4%), children 7–13 years old (24.8%), and people over 70 years (22.6%). The highest level of seropositivity, except for the children and the elderly, was found among educational workers (26.7%). The lowest level of seropositivity was found in the military (8.7%) and the unemployed (8.3%). There were no statistically significant differences in the level of seroprevalence between men and women.
Conclusions. The results of the seroepidemiological study demonstrated that in the Khabarovsk Krai, the presence of the contacts with COVID-19 patients is associated with the 1.4-fold increase in the likelihood of the seroconversion. Antibodies were detected in 58.9% of the past COVID-19 cases. In individuals with the previous positive PCR test result, antibodies were detected in 50% of cases. A high rate of asymptomatic infection, up to 93.7%, was observed among seropositive volunteers.

Aim. To assess the potential role of M. osloensis in genital microbiota of infertile males and females..
Materials and methods. Samples from men’s urethra and women’s posterior vaginal fornix in barren couples of the reproductive age were examined. Cultivation was carried out using elective culture media with subsequent identification of strains by biochemical properties. A metagenomic study of 16S ribosomal RNA samples was performed on the Illumina MiSeq platform using the MiSeq Reagent Kits v3 kit (600-Cycle Kit).
Results. Metagenomic study of samples from genital tracts of barren married couples, as well as from patients with suspected «acute genital gonococcal infection» demonstrated that all samples (100%) contained fragments of the Moraxella spp. genome, mostly in a huge amount, among which M. osloensis occupied leading positions. In women, the proportion of M. osloensis was twice as large as in men (25.3 ± 9.0 and 11.7 ± 9.3%, respectively). A high frequency of association of M. osloensis with other opportunistic pathogens, G. vaginalis and E. faecalis in particular, was established. It appears that M. osloensis can contribute to development of asymptomatic inflammatory process. Moreover, the constant presence of moraxellas in the microbiota during gonococcal infection may indicate their certain pathogenetic activity, and the synergistic nature of the relationship between M. osloensis and N. gonorrhoeae.
Conclusion. We assume that it is M. osloensis that forms the consortia determining pathosymbiocenosis in the reproductive organs. In this context, we propose to consider a decrease in fertility with a steadily established symbiocenosis, including moraxella, as an indicative condition for this pathology, and M. osloensis as its marker.

Aim. Our aim was to perform phylogenetic analysis of Vibrio cholerae O1 El Tor biovar strains, isolated from the Caucasus region over the years, using MLVA and wgSNP methods.
Materials and methods. We studied genomic sequences of 16 clinical V. cholerae O1 strains of El Tor biovar isolated on the territory of Caucasus from 1970 to 1998. These strains were obtained from the State Collection of Pathogenic Microorganisms of Stavropol Plague Control Research Institute. 87 whole genome sequences of V. cholerae strains, obtained from NCBI database, were also included in the analysis. MLVA-typing was carried out at 5 VNTR-loci. Whole genome sequencing was performed on Ion Torrent PGM platform.
Results. We determined that the studied strains belong to 15 MLVA-types and are divided in 3 groups of 1 cluster. We performed an analysis of the structure of the main virulence and pathogenicity islands, as well as nucleotide polymorphisms in ctxB, tcpA, RstR genes. We performed a wgSNP-based phylogenetic analysis of the strains, and described SNPs, specific for each phylogenetic group.
Conclusion. We confirmed the polyclonal origin of genetically modified variants of V. cholerae O1 biovar El Tor. We determined the place of V. cholerae strains of biovar El Tor, isolated from 1970 to 1998 on the territory of the Caucasus, in the global population of the pathogen. It is shown that during this period, strains belonging to the first and second waves of the seventh cholera pandemic circulated within the Caucasus. It was confirmed that cases of cholera in the Caucasus were imported from the territory of endemic countries, and the most probable sources of infection were identified.

The first part of the literature review on the role of intestinal microbiota dysbiosis in the pathogenesis of autism spectrum disorders (ASD) includes recent data published in the literature on the features of the quantitative and qualitative composition of the intestinal microbiota in patients with autism. It was shown that an excessive presence of Clostridium was detected in ASD, and evidence was presented showing the possible participation of these bacteria in the development of autism symptoms. Contradictory research results on an increase in a number of other pathogenic bacteria and, conversely, a decrease in the number of bacteria necessary to maintain the normal functioning of the intestine and the host organism as a whole are presented. The possible role of Candida albicans in ASD, requiring further study, is reported. Possible causes of contradictions in the results of studies on this topic are discussed.

Purpose: analysis of the arbovirus infections incidence in the south of the European part of the Russian Federation in 2015–2019.
Materials and methods. Data from statistical documentation (epidemiological examination of the infectious disease cases, reports on the arbovirus infections incidence) reported by Departments of Rospotrebnadzor to Scientific and Methodological Center for monitoring pathogens of infectious and parasitic diseases of 1–3 risk groups for subjects of the North Caucasian and Southern Federal Districts were analyzed. The obtained data were processed using Microsoft Excel 2010 program.
Results. In the south of the European part of the Russian Federation Crimean-Congo hemorrhagic fever (CCHF), West Nile fever (WNF), tick-borne viral encephalitis and dengue fever cases are registered annually.
An expansion of the territory with registered epidemic manifestations of CCHF and WNF was noted, reflecting an increase in the area of circulation of their pathogens. An expansion of CCHF and WNF epidemic season with the involvement into the epidemic process of people from all age groups including young children was observed. Significant increase in number of imported cases of dengue fever was documented. Markers of tick-borne viral encephalitis, Batai, Inko, Sindbis, and Tyaginya fevers were detected in residents of a number of territories. A high levels of population humoral immunity to West Nile, Batai, Inko, Sindbis Tyaginya, Ukuniemi, Bhanja, Dkhori viruses were identified in the Astrakhan region.
Conclusion. The data obtained indicate the need for epidemiological surveillance both for arbovirus infections with a pronounced epidemiological and clinical manifestations, and for infections, the proportion of which in the structure of infectious pathology in southern Russia has not been sufficiently studied, but carrying a potential risk of spreading.

Allergen-specific immunotherapy (ASIT) has been used for more than a hundred years to treat patients with IgEmediated allergic diseases. The most common allergens have been obtained using molecular cloning technology in the past two decades. To increase the safety of immunotherapy, a large group of genetically modified allergens with reduced allergenic activity was created. The mechanism of action of these therapeutic allergens differs from natural allergen extracts, and more research is needed to understand how desensitization occurs in each case. The objective of this review is to introduce readers to new therapeutic allergy vaccines and their structural modification features as well as immunological effects on the body. To achieve this objective, we have analyzed and systematized the experimental developments presented in the literature on the main directions of creating new allergy vaccines: hypoallergenic derivatives of recombinant allergens, T cell epitope-based allergy vaccines and B cell epitope-based allergy vaccines, DNA vaccines.
Summing up the results of the research presented in the literature, it is necessary to note the high heterogeneity of designs used to achieve the high efficiency of the developed therapeutic allergens. All allergy vaccines presented in the review solve the tasks set by the researchers: in experimental animal models they induce immunogenicity or tolerance, in clinical trials they reduce the symptoms of allergic reactions. The the effectiveness of the proposed medicinal products is quite high but its evaluation requires further long-term preclinical and clinical trials to confirm the safety and harmlessness of the created allergy vaccines.

The course of the Spanish flu on the territory of the former Russian Empire is not well studied. This is due to the state of the medical statistics during the times of the Civil War. The medical data was collected more diligently by the Soviet Russia rather than by the officials of the White Army.
This article discusses the timeline, symptoms, morbidity and mortality of the Spanish flu. The materials used in this article were obtained from the regional hospital archives, printed publications, and personal memoirs.
The virus of the Spanish flu has initially entered the territory of Russia at the end of August of 1918 through the demarcation line with the German army at the temporary western border defined by the Treaty of Brest. In the beginning of September the virus was carried out by the Allies army through the ports of Murmansk and Arkhangelsk. In the European part of Russia, the outbreak started around September–November of 1918. So far, there is not enough data regarding pandemic flu in Siberia and Far East region of Russia. The unknown illness that undermined the combat capability of the 11th Red Army at the end of the fall of 1918 was likely of viral etiology. There was no evidence found that pandemic flu in Russia had high mortality.
The possible correlation between atypical malignant nature of typhus and relapsing fever, the epidemics of which began in the fall of 1918, and the previous exposure of the population to the influenza virus has been hypothesized. Another hypothesis under discussion is about the possible correlation between outbreaks of the malaria and measles and subsequent susceptibility to the pandemic Spanish flu virus.

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