Journal of microbiology, epidemiology and immunobiology

Relevance. Hepatitis E virus (HEV) is a common cause of viral hepatitis not only in areas with low levels of water supply and hygiene, but also in industrialized countries. Rapid tests development for the infection seromarkers detection in the absence of special equipment and trained staff remains the most important problem in improving the diagnosis of hepatitis E.

Aim. To produce conjugates of recombinant ORF2 antigen of HEV genotype 3 with gold nanoparticles (GNP) of varied sizes and to evaluate their applicability in the immunoassay for the detection of antibodies to HEV.

Materials and methods. Specific polyclonal and monoclonal antibodies, recombinant antigen ORF2 of hepatitis E virus genotype 3, blood serum samples of people diagnosed with acute hepatitis. Synthesis of GNPs and their conjugates with recombinant antigen, enzyme immunoassay, dot immunoassay, immunochromatographic analysis, transmission electron microscopy.

Results. Three samples of colloidal GNP were synthesized using citrate method with varied concentrations of reducing agent and were subsequently used for preparation of conjugates with recombinant antigen ORF2 of HEV genotype 3. Immunoreactivity of these conjugates was confirmed by dot-immunoassay with blood serum samples containing specific IgG. A conjugate based on a 41 nm GNP was chosen for use in immunochromatographic analysis (ICA). Optimal conditions for preparation of a multi-membrane composite, including formation of analytical and control lines and the conjugate area were identified, and test strips were developed. The obtained conjugate was tested by ICA using blood serum samples which had been subjected to preliminarily characterization by the content of the IgG antibody to HEV. High immunoreactivity of the conjugate was demonstrated. Antibodies to the virus were identified in 100% of the examined (n = 17) IgG-positive serum samples, while in negative samples (n = 17) they were absent.

Conclusion. The results demonstrated effectiveness of the obtained immunoreagents (recombinant antigen, antibodies, conjugate) for use in test-systems for rapid diagnosis of hepatitis E.

Introduction. In 2022, the World Health Organization declared monkeypox a public health emergency. The monkeypox virus (MPV) is part of the Orthopoxvirus genus within the Poxviridae family. During replication, orthopoxviruses produce two distinct forms of viral particles: the extracellular enveloped virion (EEV), released via exocytosis, and the intracellular mature virion (IMV), released through cell lysis. These forms differ in surface proteins composition, influencing their immunogenicity and infectivity.

Aim. To evaluate the immunogenic and protective activity of nine surface antigens of vaccinia virus.

Materials and methods . Recombinant human adenoviruses type 2 (rAd2) carrying surface antigens of vaccinia virus were obtained using homologous recombination in bacteria, followed by adenoviral particle assembly in HEK293 cells. The immunogenic and protective properties of these adenoviruses were tested in BALB/c mice. The presence of antibodies to the vaccinia virus was assessed using ELISA, and survival rates were evaluated in a lethal infection model after intranasal challenge with the vaccinia virus strain Western Reserve.

Results. The most immunogenic and protective antigens of the vaccinia virus within rAd2 were glycoprotein B5 of the EEV and membrane-associated protein H3 of the IMV, both showing 100% protective efficacy after intranasal immunization.

Conclusion. Using a panel of recombinant adenoviruses carrying genes of vaccinia virus surface proteins, it was shown that optimal protection is achieved using a combination of enveloped and mature virion antigens. This method could be used for development of new multivalent preparations against various viral infections.

Background. Data on the prevalence of post-COVID-19 condition (PCC) in children differ due to the lack of specific diagnostic criteria, reliable biomarkers, and limitations of many studies. It is important to study the association between PCC, previous functional disorders, and any events in the post-acute period of COVID-19 to estimate the true burden of PCC in children.

The aim. To determine of the prevalence of PCC in relation to initial functional disorders in children during the year after a mild form of COVID-19 and acute respiratory tract infections (ARTI) of other etiologies.

Materials and methods. The prospective study using a continuous sampling method included children under 18 years of age hospitalized with suspected COVID-19, in whom COVID-19 was confirmed by RT-PCR (n = 121) or excluded by molecular and serological methods (ARTI group, n = 105). Information on patients was collected from September 2020 to December 2021 by questionnaires at index points: hospital discharge and after 1, 3, 6 and 12 months. Severe COVID-19 and patients with chronic diseases were excluded. Functional disorders in the anamnesis and any events associated with health disorders during the year of observation, the severity of symptoms were taken into account. The analysis was performed in groups of children < 6 years and ≥ 6 years of age. Symptoms were grouped into clusters.

Results. Any symptoms were identified with a frequency of 32–39% (in children < 6 years and ≥6 years, respectively). The most common were psycho-emotional, respiratory and autonomic dysfunction (AD) cluster. Symptoms in most cases were mild with a duration of 3–6 months. After adjustment for age, AD history and recurrent ARTI episodes, no difference was found in the symptom clusters prevalence between confirmed and excluded COVID-19, except for hyposmia, the incidence of which in children ≥6 years decreased from 14.3% at the first index point to 2.4% after one year. Among patients without an AD history and without recurrent ARTI during the year, de novo PCC was a rare phenomenon (2.7–8.0%) without differences between COVID-19 and controls. The risks of PCC were significantly increased in patients with an AD history (adjusted OR at 1 month 3.19 (95% CI 1.89–5.38), at 6 months 3.33 (95% CI 1.81–6.15)). Multiple (5–25) and persistent (at all index points) symptoms rated by patients as significant occurred de novo rarely (1.7% (95% CI 0.4–4.9)), but significantly more often in children with an AD history — 25%) 95% CI 13.6–39.6%) (difference 23.3% (10.9–35.7%), OR 14.8 (4.4–50.6), p < 0.001). Recurrent episodes of ARTI were an important risk factor for an increase in cognitive cluster complaints and vagotonic AD after 3–6 months of observation.

Conclusion. The results obtained indirectly support the concept that PCC is a somatoform functional disorder, probably of sociogenic nature, in patients who are anxious at baseline. Some patients with the COVID-19 and ARTI consequences really need medical and psychosocial rehabilitation. The study of PCC provides new insights into the consequences of widespread respiratory viral infections.

Introduction. Enterococcus spp. which are representatives of the intestinal normal microbiota, play an important role in ensuring colonization resistance of mucous membranes, producing antimicrobial compounds, and therefore are widely used as the basis of probiotic drugs. In the last decade, infections caused by Candida fungi have become a serious clinical problem. In this regard, it is relevant to evaluate the probiotic characteristics of the E. faecium strain 18 and study its antifungal activity.

The aim is to investigate the effect of the E. faecium strain 18 on the growth and mature biofilm of Candida spp., as well as to characterize its agregation and coagregation abilities.

Materials and methods. The effect on fungal growth was determined by the dynamics of the optical density of broth cultures; the effect of enterococcus supernatant on formed biofilms was studied in sterile polystyrene 96-well plates. The probiotic potential of E. faecium strain 18 was assessed by its ability to autoagregate and coagregate interaction with 20 strains of Candida of different species — C. albicans, C. krusei, C. kefir, C. glabrata. The scanning electron microscopy was used to obtain images.

Results. The inhibitory effect of the supernatant of E. faecium strain 18 has been shown to affect the growth of Candida of all studied species, as well as their mature biofilms. The level of inhibition of the growth of formed biofilms in non-albicans species was 58.6–72.9% and 51.4% for C. albicans. The autoagregation rates of E. faecium strain 18 were 57.6% after 2 hours of incubation and 60.4% after 5 hours. E. faecium strain 18 demonstrated different levels of coagregation with the studied species of Candida, with the index values observed after 5 hours of cultivation being higher in non-albicans species, and the maximum value recorded for C. glabrata (85.6%).

Conclusion. The experimental data obtained allow us to consider the studied strain as the basis for a probiotic that has an anti-candidiasis effect.

Introduction. Evaluation of hepatitis virus genotypes diversity plays a significant role in analysis of epidemiological situation in particular territories which allows to trace possible routs of transmission, emergence and spread of new viral variants.

The aim of the study is to evaluate dynamic of incidence of chronic forms of viral hepatitis B and C in the Khabarovsk krai during 2013-2023 and to perform analysis of genetic diversity of hepatitis B and C viruses (HBV and HCV) that were circulating in the Khabarovsk city.

Materials and methods. A retrospective analysis of the incidence of chronic forms of hepatitis C in the Khabarovsk krai was conducted for the period from 2013 to 2023 (11 years) according to reports from the Office of Rospotrebnadzor in the Khabarovsk krai. Serological and molecular-genetic analysis of 112 blood plasma samples obtained from patients with diagnosis of “chronic viral hepatitis” residing in the Khabarovsk city was conducted.

Results. The research showed that incidence of chronic viral hepatitis C has declined from 50.0 in 2013 to 44.6 cases per 100 thousand population in 2023 and incidence of chronic viral hepatitis B has also declined from 10.2 to 8.2 cases per 100 thousand population in the Khabarovsk krai respectively. HBV DNA was detected in 21 out of 36 blood plasma samples that contained serological markers of HBV. HBV genotype D was isolated in 15 out of 17 samples and was presented by two subtypes (D1, D2). Subtype A2 was identified in 2 samples. No mutations of drug resistance were found. HCV RNA was found in 58 out of 78 samples of blood plasma that were positive for antibodies (IgG + IgM) to HCV. Circulation of 1b, 1a, 3a, 2a, 2c HCV subtypes with predominance of 1b subtype was revealed in the Khabarovsk city.

Conclusion. The incidence of chronic hepatitis B and C in the Khabarovsk krai during the 11-year follow-up period had a pronounced tendency to decrease. Results of the research complement existing data on circulation of HBV and HCV genetic variants in territories of the Russian Federation.

The concept of resistotype represents a new characterization of bacterial communities distinct from their taxonomic composition. The term “resistotype” is now commonly used to refer to specific clusters within a resistome that possess a characteristic phenotypic profile, or set of antimicrobial resistance genes. In contrast to traditional approaches that focus on individual resistance genes or phenotypic manifestations of resistance, resistome analysis allows resistance to be considered at a more comprehensive level, integrating different genes and their interactions within microbial populations or an entire microbial community.

The aims and objectives of the review are to analyze and summarize current data on how resistotypes of individual microbial species and bacterial communities are identified and analyzed.

Literature sources devoted to the identification of resistotypes of individual bacterial species and bacterial communities of humans and farm animals over the past 10 years were analyzed.

At the current moment, identification of microorganism resistotypes is not a common practice for studies related to resistance analysis. Phenotypic research methods, rarely supplemented by genetic or genomic data, are currently used to identify resistotypes of bacterial isolates. Metagenomic sequencing and bioinformatics analysis methods are used to identify resistome and resistotypes of microbial communities.

Conclusion. Identification of resistotypes provides additional assessment of resistome in different microbial populations. Resistotype analysis can be applied both in clinical practice, to select the most appropriate method of therapy, and in agriculture, to improve the control of antibiotic resistance of microorganisms pathogenic to animals.