Journal of microbiology, epidemiology and immunobiology

The topic of epidemiologic surveillance is one of the basic concepts in the theory and practice of epidemiologic science. In Russia, generalization of the accumulated factual material and theoretical developments have allowed us to formulate a number of provisions on the nature of the epidemic process. The pandemic of a new coronavirus infection has forced adjustments in all spheres of society, including the activities of the infectious disease epidemiological surveillance system, requiring the development and implementation of innovative solutions. Based on the experience of prompt response to the tasks set by the COVID-19 pandemic, the authors raised the problem of development and implementation of a system of molecular genetic monitoring for pathogens of emerging and re-emerging infections as a priority vector of epidemiological surveillance development.

The introduction of modern molecular biological technologies for the identification of pathogens with epidemic potential, taking into account their genetic diversity, into the system of epidemiologic surveillance has been substantiated based on the experience of using platform solutions created by the Central Research Institute of Epidemiology of Rospotrebnadzor. The strategy of genomic epidemiologic surveillance as a powerful tool to ensure readiness for response measures and management of the epidemic process by implementing and adjusting preventive and anti-epidemic measures was developed.

The Russian platform for aggregation of information on virus genomes (VGARus) developed at the Central Research Institute of Epidemiology of Rospotrebnadzor as a technological, scientific, organizational and infrastructural base of genomic epidemiological surveillance, acting as an interdepartmental consortium, has been introduced into practice. The efficiency of VGARus was shown to assess the mutational variability of SARS-CoV-2, the influence of evolutionary development of circulating pathogens on the characteristics of the epidemic process, the implementation of operational and retrospective analysis of morbidity and prediction of the spread of genetic variants of pathogens.

Introduction. Infections of the lower respiratory tract by bacteria of the Pseudomonadota phylum: Pseudomonas aeruginosa, Burkholderia spp., Achromobacter spp. are critical to the quality and life expectancy of patients with cystic fibrosis (CF). When the infection is chronic, eradication of bacteria with existing antibacterial drugs is practically impossible. To explore alternative drugs, trials are needed on bacteria isolated from CF patients and characterized using genomic approaches.

The objective of our study was a comparative analysis of virulence factors of 6 isolates of bacteria of the Pseudomonadota phylum and testing the efficacy of the innovative drug Fluorothiazinone (FT) in suppressing the pathogenicity of bacteria in vitro.

Materials and methods. Isolates of A. ruhlandii ST36, A. xylosoxidans ST555, B. cepacia ST2140, B. gladioli ST2141, P. aeruginosa ST859 and ST198 were examined using whole-genome sequencing and bioinformatics analysis to search for resistance and virulence determinants. The FT drug was tested for its effect on bacteria in in vitro experiments on cytotoxicity on HeLa cells, motility and biofilm formation.

Results. Genomic studies have confirmed the arsenal of resistance determinants, especially the efflux systems of bacteria isolated from patients with CF, and the diversity of virulence factors, among which we identified factors in the categories of motility, signals of quorum-sensing systems, secretion systems, exotoxins, as the most essential for the adaptation of bacteria to conditions of the lower respiratory tract. In vitro tests of the FT drug showed its effectiveness in suppressing cytotoxicity (2.6–4.0 times), motility (2.0–3.6 times) and the process of biofilm formation (2.0–7.7 times).

Conclusion. For the first time, the effectiveness of the innovative antibacterial drug Fluorothiazinone has been shown against bacteria of the Pseudomonadota phylum, isolated from chronically infected patients with CF, with the described potential of virulence factors.

Introduction. Chikungunya virus infection is a problem for the health care system of affected regions due to the lack of specific prevention, as well as effective antiviral drugs. The critical role of cellular immunity in viral control and clearance for the Chikungunya fever has been demonstrated in many studies. Therefore, effective stimulation of not only humoral but also cellular immunity is of undeniable importance when assessing the effectiveness of a potential vaccine for the prevention of this infection.

The aim of the present study was to investigate the formation of protective immunity after administration of a drug containing inactivated Chikungunya virus (CHIKV) to C57Bl/6 mice.

Materials and methods. Inactivated CHIKV (concentrations of 10 μg and 40 μg) was administered intramuscularly to C57Bl/6 mice twice with an interval of 14 days. Indicators of humoral immunity were assessed by ELISA and neutralization test (NT), cellular immunity — by the production of IFN-γ and splenocyte proliferation in vitro. The concentration of cytokines IL-1, IL-2, IL-6, IL-10, IL-12p70 and TNF was determined by ELISA. When assessing the protective immunity in animals, CHIKV was injected into the dorsal surface of the foot of the right hind paw at a dose of 2.89 ± 0.10 lg TCD50 in a volume of 20 μl.

Results. The most pronounced immune response was noted to the administration of 40 μg of inactivated CHIKV, which was manifested in the balanced production of the studied cytokines, the formation of specific humoral (according to the results of ELISA and NT) and cellular — specific proliferation of splenocytes in vitro and production of IFN-γ. When assessing efficacy, the development of foot edema in immunized animals was significantly lower than in animals in the control group.

Discussion. CHIKV, inactivated by beta-propiolactone, had pronounced immunogenic properties. The balance of production of pro- and anti-inflammatory cytokines, as well as the Th1/Th2 immune response, characterized the formation of adaptive immunity in mice without a pronounced inflammatory response. The formation of a specific humoral and cellular immune response has been demonstrated. A study of protection in a non-lethal animal model confirmed the efficacy of the inactivated vaccine.

Conclusion. Double administration of the inactivated CHIKV vaccine at a dose of 40 μg to C57Bl/6 mice demonstrated pronounced immunogenicity, which allows us to evaluate it as a promising prophylactic vaccine.

Introduction. Colonization of the reproductive organs of pregnant women with group B streptococci (GBS; Streptococcus agalactiae) can lead to severe perinatal and neonatal pathology. In modern conditions, aside from the prevention of antenatal infection of the fetus during childbirth using antibacterial drugs, vaccination is also necessary. In this regard, surveillance of GBS genotypes is an important task.

Objective. To determine the molecular genetic determinants of virulence of Streptococcus agalactiae isolated from pregnant women and newborns, and to monitor the distribution of capsular polysaccharides types and pili profiles in GBS clinical isolates.

Materials and methods. The study used clinical isolates of GBS (n = 420) isolated from pregnant women and newborns in 2010–2023.The bacteriological method was used for isolation of S. agalactiae. PCR method was used to determine the types of capsular polysaccharides, pili, and whether the strains belonged to the hypervirulent sequence type ST-17.

Results. During 13 years of observation, the predominance of Ia, III and V genotypes of GBS capsular polysaccharides was noted both in pregnant women and in newborns. The frequency of occurrence of genotype Ib increased from 0.7 to 6.7%, genotype V from 12.1 to 24.4%, and the prevalence of genotype III decreased significantly from 41.1 to 21.1%. Hypervirulent sequence type ST-17 was detected in 6 pregnant women and 2 newborns. However, there were no signs of neonatal infection in these children. More than half of all clinical isolates of S. agalactiae had pili genotypes PI-1 + PI-2a, as well as pili genotypes PI-2a and PI-1 + PI-2b. The distribution of pili types did not change over 13 years of the surveillance period.

Conclusion. Surveillance of the GBS capsular polysaccharides and pili genotypes is necessary for the development of effective preventive vaccines.

Introduction. The genetic structure of the global population of Bacillus anthracis characterized by an unequal distribution of isolates of the main genetic lineages A, B and C, the reason for which is unknown. Determining the characteristics of genes encoding factors that determine the existence of this pathogen at the intra- and extra organismal stages of the life cycle, which can influence the prevalence of strains, is relevant.

Aim — сharacterization of the genes and proteins of spore germination in strains of the anthrax pathogen of different genetic lineages.

Materials and methods. Whole genome sequences of 46 B. anthracis strains and the CI strain of B. cereus biovar anthracis from the NCBI GenBank database studied. In silico analysis carried out using the programs “BLASTn”, “MEGA X”, “Tandem Repeat Finder”.

Results. The number of SNPs, indels and pseudogenes in B. anthracis strains of line B was 2,7–25,6 times higher, in line C 2–23,5 times, and in the B. cereus biovar anthracis strain was 20–2841 times higher than in strains of line A. Significant substitutions in genes leading to changes in the amino acid composition of 10 germination receptor proteins were also significantly more common in B. anthracis strains of lines B, C and the B. cereus biovar anthracis strain.

Undescribed VNTRs within the gerHA gene with repeat units of 78 and 117 bp identified, varying between and within isolates of different genetic lineages. Six germination receptor genes have been shown to have rare starting codons.

Conclusion. A larger number of non-synonymous SNPs in the genes of spore germination receptors with changes in the amino acid composition of proteins in B. anthracis strains of the main genetic lines B, C and B. cereus biovar anthracis than in strains of line A suggests their limited adaptive capabilities and may be one of the explanations for the lower prevalence compared to line A. Differences in the gerHA and gerM genes make it possible to differentiate the major B and C genetic lineages from A.

Introduction. Immunomodulatory drugs (IMD) have great potential to increase the nonspecific reactivity of the organism in a set of measures for emergency prevention of plague. The purpose of the work is to evaluate the protective effectiveness of the use of IMD of different groups in experiments on modeling infection with a highly virulent strain of the plague microbe.

Materials and methods. IMD (rIFN-γ — recombinant interferon-gamma, PO — azoximer bromide, synthetic immunomodulatory oligopeptides O1, O2, O3) was administered to white mice and guinea pigs subcutaneously thrice by the schedule 3 days, 1 day, and 1 hour prior the infection with a virulent test strain of plague Yersinia pestis 231 (708) at dose from 1 to 625 CFU. In addition, the effect of IMD on the production of IFN-γ and interleukin-10 was investigated in white mice before infection.

Results. The study of the effect of IMD on the survival of unvaccinated biomodels made it possible to establish that only rIFN-γ and PO increase the survival of two types of laboratory animals by 20–50% and significantly increase the LD50. All tested IMD contribute to an increase in the average life expectancy of biomodels by at least one day. An increase in spontaneous and mitogen-induced cytokine production was found only in white mice receiving rIFN-γ and PO, which correlates with animal survival rates.

Conclusion. The obtained data indicate the effectiveness of the use of IMD, especially rIFN-γ and PO in protecting the macroorganisms from infection with Y. pestis, which determines the prospects for research on the further improvement of emergency prevention of plague.

Parvovirus B19 infection (PVI) is one of the relatively new problems in infectology, data on the study of its prevalence in our country began to appear only at the beginning of the twenty-first century. The article presents the results of an analysis of studies from available literature sources highlighting the prevalence of PVI markers at the population level among different social groups of the population at the present stage. The clinical manifestations of PVI are diverse, which requires differential diagnosis, both with exanthemic infectious diseases and with non-infectious pathology. Due to the peculiarity of PVI pathogenesis, it is relevant for various socially significant populations, primarily patients with exanthemic manifestations of various diseases, persons from among blood donors, pregnant women and women planning pregnancy. Furthermore, unlike most countries, our country does not have a system for PVI detecting and reporting in the system of state sanitary and epidemiological supervision, which makes it difficult to conduct research on this topic.

The problem of chronic periodontitis (CP) is actively discussed due to the recognition of the fact that periodontal microbial damage is closely related to a number of systemic diseases and probably plays an important role in the occurrence of comorbid pathology.

The aim of the meta-analysis was to characterize the composition of the subgingival microbiome and to determine the peculiarities of the formation of associations of the new periodontal pathogen Filifactor alocis with other I and II order periodontal pathogenic bacteria, as well as with the commensal bacteria colonizing this biotope.

The study presents data of patient examination with obligatory use of polymerase chain reaction methods and sequencing of 16S rRNA genes in 1529 healthy individuals and 2394 patients with CP, 136 patients with CP and concomitant atherosclerosis, 258 patients with CP and concomitant type 2 diabetes mellitus. It was confirmed that the basis of the oral microbiome under normal circumstances is composed of representatives of microaerophilic streptococci, corynebacteria, lactobacilli, as well as representatives of the Veillonella and Sphingobacterium genera. 16S sequencing and bioinformatic analysis allowed us to specify the taxonomic place of the new pathogen F. alocis, as well as representatives of normal microbiota in CP and comorbid somatic pathology.