Vol 14, No 6 (2024)

As a rule, traditional methods of cell cultivation in vitro using monolayer cell lines (2D cultivation) are unable to simulate the structural organization of a three-dimensional (3D) cell network in vivo and are insufficient for modeling living tissues to study intercellular signaling, proliferation, differentiation, gene and protein expression, reactions to various stimuli and drug metabolism. Using 2D cultivation, it is impossible to adequately reproduce a virus-host cell interaction and disease pathogenesis at the level of individual tissues. The technological platform for obtaining the most reliable results is 3D cell cultivation. Based on the analysis of scientific literature contained in the main databases (Web of Science, PubMed, Scopus, Elsevier, Google Scholar and RSCI), our review provides a brief description of various types of 3D cultures, as well as methods for their production and viability maintenance. The modern prospects of their use in virological research are discussed. The main aspects for application of 3D-cultures are analyzed: isolation, cultivation and study of mechanisms for virus reproduction, virus-host interaction, the study of immunopathogenesis and epidemiological prognosis of viral infections. The possibilities of 3D cultures for production and testing of vaccines, antiviral drugs, and, generally, for choosing a treatment strategy of viral infections are analyzed. In addition to the advantages and prospects of using 3D-cell cultures in virology, their disadvantages are also assessed. Special attention is devoted to such ex vivo 3D systems, as organoids and “organ-on-a-chip”, which largely meet the requirements of laboratory models in virological research. The hallmark characteristics of organoids is imitation of tissue organization, functionality and genetic specificity in a specific tissue or part of an organ. This approach allows to markedly increase model sensitivity for virus isolation. The review analyzes the data from numerous studies concerning the use of organoids to examine human and animal viruses, which display affinity for certain tissues and the data on assessing the features of immunopathogenesis behind respiratory viral infections.

The data on impact of chronic rhinosinusitis (CRS) on SARS-CoV-2 virus susceptibility and COVID-19 course were reviewed. CRS heterogeneity is determined by different types of inflammatory response. A heterogeneous CRS is divided into CRS without polyps and with nasal polyps (CRSwNP) is accounted for by diverse underlying immune responses. Hypersecretion of interleukins (IL)-4, IL-5, IL-13 in eosinophilic CRSwNP downmodulates angiotensin-converting enzyme (ACE)-2 receptor expression that should reduce SARS-CoV-2 infection risk because ACE2 is a main cellular tropism factor for SARS-CoV-2. In neutrophilic CRS type 1 immune response predominates, with activation of Th-1 cells, hypersecretion of interferon (IFN)-γ and tumor necrosis factor (TNF)-α to increase ACE2 expression. However, another data also show that hypoxemia level and pulmonary system damage did not differ between patients with CRS and CRS without polyps. Literature contradictions may be related to differences in availability of medical care, treatment of bronchial asthma (BA) as well as coverage of PCR testing. Regarding use of local or systemic glucocorticosteroids (GCS) effect on SARS-CoV-2 infection risk, some authors believe that GCS may increase COVID-19 severity and mortality, probably by downmodulating local innate immune response factors. According to other data, GCS may reduce ACE2 expression, or there is no relationship between previous GCS use, the incidence of COVID-19 and the frequency of treatment in the intensive care unit. Biological therapy of CRSwNP and BA with monoclonal antibodies did not aggravate COVID-19 severity and mortality risk. Although such data are currently limited, authors recommend not to interrupt such treatment during the epidemic, as well as continue taking leukotriene receptor blockers that can further inhibit major protease (Mpro) of the SARS-CoV-2 virus. However, according to international guidelines on COVID-19 treatment, using CRSwNP and asthma biological therapy should be discontinued until the patients recover completely. Allergen-specific immunotherapy (ASIT) should be interrupted in the case of confirmed COVID-19 due to a probability of developing severe COVID-19. After COVID-19, disturbances in the immune system may persist and possibly change the course of CRS, therefore requiring to modify therapeutic approaches for such patients. At the same time, the worldwide literature has been gradually accumulating information on pathogenesis underlying alterations in such patients including those with CRS, which requires development of new therapeutic approaches.

The development of chronic generalized periodontitis occurs due to a combination of a several causes, among which the leading role is assigned to periodontal pathogens, which include P. gingivalis. Among P. gingivalis virulence factors, the polysaccharide capsule, fimbria proteins, cysteine proteases, and hemagglutinins are of special importance. The study was aimed to investigate the prevalence of specific virulence genes and identify a virulent genotype among P. gingivalis isolates found in patients with severe chronic generalized periodontitis (CGP). 41 patients (27 women and 14 men, average age 43.9±1.5 years) were examined, of which main and control group consisted of 22 patients with severe CGP and 19 patients without inflammatory periodontal diseases, respectively. The PCR data allow to consider type II fimbria (FimA II), arginine-dependent type A protease (RghA) and lysine-dependent protease (Kgh) as specific markers for the detection of more virulent P. gingivalis strains. It was found that in St. Petersburg, the following P. gingivalis genotypes predominate among patients with severe CGP: fimA II:kg:rghA, fimA II:kgh and fimA II:rghA. In addition, it has been demonstrated that virulent genotypes are detected to a small extent in P. gingivalis isolates from healthy control group patients. The identification of P. gingivalis strains with a more prominent pathogenic potential and the detection of their virulent genotypes is of great practical importance, in the future allowing to develop advanced effective methods for disease prevention to be used in a personalized medicine strategy. The results obtained are also of high importance due to the recorded variability in the circulation of P. gingivalis strain genotypes in various worldwide regions.

Human nasal cavity and paranasal sinuses play a crucial role in the physiological processes in vivo that accounts for the constant attention of doctors of many specialties to the state and pathological changes in the respiratory compartments noted above. Rhinosinusites hold one of the leading places in the pattern of inflammatory pathology of the paranasal sinuses, regardless of patient age, the climatic zone of residence and living style level. Chronic vs acute rhinosinusitis is less widespread but considered to be the most common chronic disease. This pathology develops on average in 5% population, and CRS incidence increased more than by 2-fold over the last 10 years. In the pattern of subjects admitted to otorhinolaryngological hospitals, CRS comprises 25–30% that progressively elevates by mean 1–2% every year. The aim of the study was to evaluate disease phenotype-driven alterations in cellular and humoral immunity in patients with chronic rhinosinusitis. 91 patients with chronic rhinosinusitis were selected. For the study of cellular immunity, a flow cytometry was used with “Cytomics FC500” (Beckman Coulter, USA) and monoclonal antibodies CD3⁺, CD4⁺, CD8⁺, CD16⁺, CD19⁺ (Beckman Coulter, USA). To measure the levels of blood serum immunoglobulins of various classes (A, M, E, G), an enzyme-linked immunosorbent analysis (ELISA) was used. Statistical data processing was carried out using Statistica for Windows 8.0 application programs (StatSoftink, USA, 2008). The study revealed changes in the cellular and humoral links of immunity in chronic rhinosinusitis coupled to distinct disease phenotypes: with chronic allergic rhinosinusitis — 5; in chronic polypose rhinosinusitis — 4; in chronic infectious rhinosinusitis — 3; in chronic hyperplastic rhinosinusitis — 4. With allergic chronic rhinosinusitis, it was linked to higher absolute B-lymphocyte count, hypergammaglobulinemia E and a decrease in 3 indices of relative synthesis were revealed. Polypose chronic rhinosinusitis was associated with elevated in absolute B-lymphocyte level, hypergammaglobulinemia E and decrease in 2 indices of relative synthesis, whereas infectious chronic rhinosinusitis was accompanied by increased B-lymphocyte level and decrease in 2 indices of relative synthesis. Hyperplastic chronic rhinosinusitis patients had higher in absolute T- and B-lymphocyte count and a decreased absolute cytotoxic T-lymphocyte level along with 2 indices of relative synthesis.

Klebsiella pneumoniae dominates among the pathogens that cause healthcare-associated infections and closely associated with high mortality of patients undergoing heart surgery. K. pneumoniae spp. are classified into classical (cKp) and hypervirulent (hvKp): cKp causing nosocomial infections often exerting a multidrug resistance phenotype (MDR-cKp), whereas hvKp are sensitive to antibiotics, but have high virulence. Earlier, we presented the molecular genetic characteristics of K. pneumoniae bacteria isolated from patients at the cardiac surgical hospital. Here, clinical and microbiological risk factors as well as thoase underlying infection development and adverse outcome of nosocomial infection caused by K. pneumoniae were evaluated. Along with initially severe comorbidities, the most significant risk factors were the following: female gender, age over 65 years, length of stay at the Department of Anesthesiology and Intensive Care as well as other detected comorbidities. The average length of stay was 1.7 times longer among MDR-cKp vs hvKp patients. Complications (multiple organ dysfunction syndrome, bloodstream infections), as well as mortality rate were recorded only in MDR-cKp patient group. Thus, in hospital period, K. pneumoniae multidrug resistance rather than hypervirulence turned out to be a more contributing risk factor. It should be noted that one convergent MDR-hvKp isolate has been detected, which may pose a serious problem in treatment of patients upon further spread of such K. pneumoniae bacteria.

Coinfection is one of the most complex public health issues and is challenging both in choosing treatment strategy and in implementing epidemiological surveillance. The latter in the Russian Federation includes no specific monitoring after HIV and chronic viral hepatitis (CVH) coinfection. The objective of the study was to perform a retrospective epidemiological analysis of CVH, HIV-infection, HIV+CVH coinfection incidence, conduct integral assessment of HIV+CVH coinfection epidemic manifestations in the Far Eastern Federal District (FEFD) during the years 2007–2022. It was established that HIV-infection and HIV+CVH coinfection incidence showed a unilateral long-term growth trend reaching in 2022 up to 4.3 cases/100 000 population (by 6-fold higher than in 2007), which for HIV-infection incidence was as high as 30.7 cases/100 000 population (by 2-fold higher than in 2007). CVH incidence decrease with average long-term decline comprising 4.4% per year and in 2022 reaching 26.1 cases/100 000 population. Primorye Territory had highest incidence of HIV+CVH coinfection in 2022 that exceeded average level recorded among territories of the FEFD by 2.3-fold. Primorye Territory is a territory historically characterized by widespread of HIV-infection and CVH in human population partly due to broad drug use. Ranking of HIV+CVH coinfection incidence revealed territories with favorable epidemic situation as follows: Kamchatka Territory, Khabarovsk Territory, Republic of Sakha (Yakutia), Magadan Region. HIV infection and CVH are long-lasting conditions therefore individuals with verified diagnosis may remain a source of infection. Hence, the analysis of the disease incidence alone was found to be insufficient for assessing epidemic situation. Therefore, a comprehensive analysis was carried out to calculate integral index based on the sum of ranks of HIV+CVH coinfection incidence, prevalence and average long-term incidence, prevalence of CVH among HIV-positive subjects. Ranking of the integral index established unfavorable epidemic situation for HIV+CVH coinfection in the Magadan Region and Republic of Sakha (Yakutia). Both territories had an upward incidence trend, high prevalence of CVH among HIV-positive subjects. In addition, the Magadan Region had highest prevalence of HIV+CVH coinfection. Primorye Territory and Jewish Autonomous Region were also classified as unfavorable. Existing epidemiological surveillance after HIV-infection needs to be supplemented with separate monitoring over HIV+CVH coinfection. Estimating an integral index in addition to evaluation of incidence for assessment of the epidemic situation over coinfection will improve the analysis.

The results of virologically examined biological material collected from children and poliovirus-specific immunity arrived in the Russian Federation from polio high risk territories were analyzed. Over a ten-year period (2014–2023), more than 3.300 samples were examined at the Subnational WHO Laboratory in St. Petersburg. Most of the examined children arrived in different regions of the Russian Federation from the Republics of Tajikistan (56.5%) or Uzbekistan (6.2%) and from Ukraine (5.8%). Children who arrived from the North Caucasus were also examined comprising 22.2% examined cases. Polioviruses (65 PV) were isolated from 55 children during virological study. Most isolated strains were classified as types 1 and 3 polioviruses, with six strains classified as type 2. Only vaccine polioviruses were found, including type 2 polioviruses according to the ITD results. One PV2 strain was isolated from a child from Kyrgyzstan in 2014, and five PV2 strains from the new nOPV2 vaccine were isolated from Tajik children in 2021 after using nOPV2 vaccine to suppress cVDPV2 circulation in Tajikistan. Analysis of vaccination status in children arrived from high polio risk territories revealed problems poor immunization coverage in relevant place of residence. More than a third of children had no vaccination records, about 9% children had no polio vaccination for various reasons including medical exemptions and refusals of parents to vaccinate, another 12% were vaccinated incompletely. A comparatively analyzed effectiveness of polio vaccination for children resident in the Russian Federation and those who arrived from Tajikistan also evidenced poor polio immunization coverage in the latter. Many children from Tajikistan had no antibodies specific to polioviruses of different types, and 11–12% of children did not have antibodies to all three or two vaccine poliovirus types (according to the 2006–2010 or 2014–2020 vaccination schedules). The data obtained confirm the importance and need for epidemiological and virological surveillance for residents arrived from polio high risk territories in Russia within poliomyelitis control programme in the Russian Federation.

Specific measles, mumps, and rubella prevention has been the main prerequisite for a striking decline in the incidence of such infections in Russia. An increase in the percentage of seronegative individuals observed in recent years resulted in higher measles incidence being directly related to low herd immunity that accounts for a population protection solely under conditions of a high density of immunized individuals and their uniform distribution in the population. The number of immunized individuals may be estimated only while conducting seroepidemiological monitoring of herd immunity. The objective of the study was to assess a level of herd immunity in the St. Petersburg and Leningrad Region population against measles, mumps, and rubella viruses. Materials and methods. There were enrolled 6774 residents into the study: volunteers aged from 1 to 70+ years. The representativeness of the surveyed cohort was ensured by using the Web application “Monitoring of herd immunity against socially significant infections”, used at the stage of volunteer enrollment, by randomization and regulation of the sample size in age groups. Participants filled out a questionnaire and agreed to provide venous blood samples to assess IgG antibody levels against measles, mumps, and rubella viruses by using ELISA. Results. In September 2023, in St. Petersburg and the Leningrad Region, herd immunity met the criterion for epidemiological well-being only with respect to rubella. In all age groups, the proportion of seronegative individuals did not exceed 15%, and most volunteers had high Ab levels, both after illness and vaccination. For measles and mumps, the criterion for epidemiological well-being is considered not to exceed more than 7% seronegative individuals. A sufficient level of measles seroprevalence was detected only in older age groups (≥ 60 years old). Sufficient mumps seroprevalence was not detected in any age group. The average population (St. Petersburg, Leningrad Region) seroprevalence magnitude for measles, rubella, and mumps viruses were 81.4%, 95.5%, and 78.4%, respectively. The problematic age groups with low measles seroprevalence (62.4–74.3%) were adolescents (12–17 years) and young adults (18–39 years). Most seropositive individuals vaccinated against measles had low Ab levels; high levels were noted mainly in older measles convalescent individuals. Low mumps seroprevalence (~70%) was more often observed among adults aged 18 to 49 years. The distribution of seroprevalence in various occupational group was relatively uniform, with some predominance of seropositivity among pensioners and schoolchildren. Conclusion. The system of specific prophylaxis for vaccine-preventable viral infections used in Russia has shown high efficacy and contributed to the formation of herd immunity, which for many years allowed to lower a risk of both sporadic and group infections to minimal levels. Currently, measles and mumps seroprevalence in the local population is maintained at insufficient level to ensure epidemiological well-being. This necessitates making appropriate management decisions and conducting additional preventive measures aimed at enhancing relevant herd immunity.

Here, we analyze the spread of parvovirus B19 infection in the Northwestern Federal District from the years 2018 to 2023. It was shown that cases of infection were recorded in 10 out of 11 territories, excepting the Nenets Autonomous Okrug. Overall, IgM antibodies to parvovirus B19 (B19V) were detected in 295 samples out of 2079 tested (14.1%). The prevalence of parvovirus B19 infection varied over the years of the study: in 2023, an increase in incidence was detected in the Northwestern Federal District, with an indicator of 0.93 per 100 thousand population, which significantly exceeded the long-term average level of 0.43 per 100 thousand population in the district. Children under 14 years of age predominated in the age pattern. The virus circulated most actively in St. Petersburg and the Leningrad region, which is due to the high population density in these territories and the many municipal institutions where long-term close contacts between people take place. The winter-spring seasonality of the infection has been confirmed. An analysis of primary diagnoses in patients with laboratory-confirmed parvovirus infection (2022) showed that the correct clinical diagnosis was not established in any case. The most common clinical diagnostic errors were: “Acute respiratory infection”; “Measles” and “Rubella”; herpes virus infections. In 30% of cases, parvovirus B19 infection was assessed by clinicians as a non-infectious disease. Errors in the initial diagnosis of parvovirus infection can contribute to the spread of infection, including in risk groups. Thus, while examining patients at a dialysis center, laboratory methods revealed latent parvovirus B19 circulation in this risk group confirmed by the detection of B19V DNA and virus-specific IgM antibodies in some samples tested. The seroprevalence established among patients not exceeding 76.9% accounts for an opportunity of infection spread among patients seronegative for parvovirus B19 with worsening of disease course and prognosis. Considering the widespread distribution of parvovirus infection, when identifying infectious diseases and respiratory diseases that occur with unclear exanthema manifestations among people at risk and/or from organized groups, it is advisable to conduct targeted serological monitoring for laboratory markers of parvovirus B19 infection. One of the directions for further qualitative study of parvovirus infection is to solve an issue of its identification and recording in the epidemiological surveillance system.