Vol 14, No 5 (2024)

Although the history of the influenza virus existence goes back thousands of years, the first human influenza A virus was discovered only in 1933, when proper models and substrates for virus isolation became available; then the influenza B virus was isolated and, some later, the influenza C virus. Influenza A viruses evolve most rapidly. Influenza B viruses mutate 2–3 times slower, with influenza C viruses being most conservative. From the moment of isolation until the end of the 1970s, the antigenic evolution of influenza B viruses proceeded smoothly; the isolates were genetically quite homogeneous. In the 1970s–1980s, influenza B viruses diverged into two genetic lineages, “B/Victoria/2/87-like virus lineage” and the “B/Yamagata/16/88-like virus lineage”. For some time, B/Yamagata lineage viruses were widespread throughout the world, while the circulation area of B/Victoria viruses was limited to East Asia. Then the Victorian lineage began its triumphal march across the globe. From this moment on, both lineages of influenza B virus circulated together, with dominance of one or the other lineage in different geographic regions and different epidemiological seasons. Later, the B/Yamagata lineage dominated in many countries, but by the onset of the COVID-19 pandemic, Victorian viruses were already dominant. At the same time, the last representatives of the B/Yamagata lineage were identified. Today, the B/Yamagata lineage has disappeared from circulation and the WHO has concluded that its inclusion in influenza vaccine strains is no longer necessary. Antigenic variability undoubtedly plays a decisive role in the virus evolution. It is accompanied by changes in biological characteristics that, to one degree or another, determine the virus’s ability to self-preserve. No matter how antigenically new a next influenza virus variant is, it will bear a certain set of biological properties, the combination of which will allow the pathogen to best survive in sensitive host. In this review, we have summarized information on the most striking biological properties of influenza B viruses, such as sensitivity to nonspecific blood serum inhibitors, hemagglutinin receptor specificity, its thermostability, sensitivity to low pH values, and temperature sensitivity of reproduction.

Introduction. The emergence and spread of new genetic variants of SARS-CoV-2 underlies periodic upsurge in COVID-19 incidence. It has been shown that the most rapidly spreading genetic variants of SARS-CoV-2 are resistant to antibodies specific to the previous variant of the SARS-CoV-2, thereby necessitating to analyze the antibody evasion ability of previously circulating variants for newly emerging subvariants. The aim of this work was to assess SARS-CoV-2 cross-reactivity of coronavirus strains belonging to different genetic subvariants of Omicron isolated in the territory of the Russian Federation in the period 2020–2023 in microneutralization reaction using hyperimmune mouse sera. Materials and methods. Mouse hyperimmune sera were obtained against 10 SARS-CoV-2 strains belonging to subvariants BA.1, BA.2, CH.1.1, BN.1, BA.5.1, CL.1.2, BA.5.2, BQ.1.2.1 XBB.1.5 and XBB.3. BALB/c mice were immunized with inactivated concentrated antigen mixed at 1:1 ratio with an adjuvant representing Quillaja saponaria saponin-based virus-like immunostimulatory complex. The antibody titer was determined by neutralization test. The neutralizing activity of the hyperimmune sera was analyzed against the relevant viruses as well as against previous genetic variants of SARS-CoV-2 (Wuhan, Alpha, Beta, Gamma, Delta). Results. Cross-reactivity for all Omicron-variant strains analyzed here was shown; the degree of cross-reactivity depended on the degree of inter-strain relatedness. A prominent cross-reactivity was observed for subvariants of BA.5 so that their neutralizing activity against recombinant SARS-CoV-2 lineages was markedly reduced. Neutralizing serum titers obtained for subvariants of BA.5 against genetic variants of SARS-CoV-2 isolated during the early periods of the pandemic are reduced more than 60-fold. Conclusion. The presented method for obtaining and using hyperimmune mouse sera for neutralization reaction allows the assessment of cross-reactivity for strains belonging to different SARS-CoV-2 subvariants.

The evaluation of cellular immunity to SARS-CoV-2 is a critical tool for assessing vaccination efficacy and development of post-infectious immunity. According to available studies, virus-specific T cells persist longer than antigen-specific antibodies and play a pivotal role in the effective virus elimination from human body. Current methodologies for assessing virus-specific T cells are mostly based on flow cytometry, which require specialized laboratory equipment and highly trained personnel. An alternative approach involves a skin test conducted to assess delayed-type hypersensitivity (DTH) reactions. For this, there has been developed the “CoronaDerm-PS” substance, a sterile isotonic solution for intradermal administration, containing a recombinant hybrid protein that incorporates regions of SARS-CoV-2 structural proteins S, M, N, and E, produced by a genetically modified E. coli BL21 strain cell culture. Following preclinical studies that demonstrated the safety of the above-noted medication, Phase I and Phase II clinical trials were initiated to evaluate safety and specific activity of “CoronaDerm-PS” in apparently healthy volunteers with SARS-CoV-2 post-vaccination and post-infection immunity. In Phase I clinical trial with COVID-19 unexposed or vaccinated volunteers, the data were obtained demonstrating the safety and good tolerability of the medication, thus enabling the progression to Phase II. The Phase II results provided additional evidence on the preparation’s safety in individuals with SARS-CoV-2 post-vaccination and post-infection immunity, as assessed by clinical and laboratory data. No serious adverse events were observed during the study, and in 93.5% cases, adverse events required no therapeutic or diagnostic intervention. To assess the specific activity of the preparation, the skin test data were compared with the IFNγ production stimulation index for CD4⁺ T lymphocytes assessed by flow cytometry. The ROC analysis revealed sensitivity magnitude ranging from 76.6% to 84%, and specificity level ranging from 80% to 87.5%. Based on ROC analysis results, “CoronaDerm-PS” can be an informative diagnostic tool (AUC = 0.795), demonstrating high sensitivity (79.8%) and specificity (80.8%), with consistent results across different volunteer cohorts. Analyzing the collected data suggests that “CoronaDerm-PS” is a robust alternative to laboratory methods for evaluating SARS-CoV-2-specific T-cell immunity, with high sensitivity and specificity, suitable for large-scale screening.

Due to the high prevalence of acute respiratory infections in children, it was of interest to determine the composition of bacterial and viral-bacterial associations for respiratory tract inhabiting microorganisms. To identify respiratory tract pathogens, especially viruses and unculturable bacteria, it is advisable to use molecular genetic research methods particularly PCR. The work was aimed at comparatively analyzing rate of genome detection for respiratory tract pathogens in children with acute respiratory infections and apparently healthy controls. Materials and methods. Children (97 people) were examined, of which 35 people — with acute respiratory infections of the upper respiratory tract (nasopharyngitis, pharyngitis, laryngitis) (ARI URT), 32 people — with acute respiratory infections of the lower respiratory tract (acute bronchitis, acute obstructive bronchitis) (ARI NDP) and 30 people — apparently healthy control at the time of examination. RNA and DNA of viral and bacterial pathogens were assessed in the oropharyngeal smears using PCR. Test systems produced by the Federal Budgetary Institution Central Research Institute of Epidemiology of Rospotrebnadzor and JSC Vector-Best were used. Results. An analysis of detection rate for DNA and RNA of bacterial and viral pathogens showed the presence of a wide range of them (20 different species/strains out of 27 identified) in oropharyngeal biomaterial from all examined children. The peak diversity and detection rate of pathogen genomes were found in apparently healthy subjects and children with ARI UDP (DNA of members from Herpesviridae family, S. pneumoniae, H. influaenzae, MSSA, MRCoNS). Associations of 4–6 pathogens prevailed in the microflora, and the “core” of both bacterial and viral-bacterial associations was the combination of S. pneumoniae and H. influenzae (in 93.3% and 60.0% of cases, respectively). In bacterial associations, staphylococci (MRSA and MRCoNS) and P. aeruginosa were also detected in healthy children, MSSA and other very rarely bacterial types were detected in children with ARI UDP. In children with NPD infections, the majority of whom (75.0±7.7%) were classified as long-term ill and had a complicated disease course, a noticeable depletion (decrease in taxonomic diversity) of the nasopharyngeal microbiota was found. Conclusion. The presented data indicate the presence in the biomaterial of the examined children of molecular genetic markers of a wide range of pathogens presented as viral-bacterial and bacterial associations, with varying composition being related to patient clinical status. Detection of pathogen genomes is important for choosing proper etiotropic therapy at early disease stages as well as prescribing probiotic drugs that can restore a balance in respiratory tract microflora.

“Dry” immersion is one of the methods for simulating some factors of a space flight. Volunteer-derived intestinal microbiota previously studied by “dry” immersion showed profoundly deteriorated state of microflora and blood protein composition. The study was aimed to analyze mechanisms underlying a positive correlation with amount of intestinal E. coli, and negative correlation between S. aureus and Enterobacter spp. with the number of human blood proteins assessed by proteomics methods based on mass spectrometry, in a 3-day experiment “dry” female immersion. 6 female volunteers aged from 25 to 40 years took part in the 3-days “dry” immersion experiment. During the experiment, the subjects did not take any drugs that could affect the microflora. Fecal samples were collected once per 1–2 days before the onset of the experiment and once on days 1–3 after the end of the “dry” immersion, number of microorganisms in the above-mentioned samples was assessed. Capillary blood samples were obtained by puncture of the terminal phalanx of the ring finger 2 days before the onset of the experiment, on day 1, 2 and 3 during dry immersion and 2 days afterwards. The relationship between the level of proteins in the samples and the number of intestinal microorganisms was described using a regression model in which the blood specific protein was a dependent variable, and the number of microorganisms was an independent variable. The STATISTICA 12.0 program was used for data processing. When analyzing the data obtained, 30 proteins were identified, which positively correlated with the amount of E. coli and negatively correlated with the amount of S. aureus and Enterobacter spp. While considering the events in which these proteins are involved in the human body, they were divided into several groups. In the current study, there were examined 6 proteins associated with infectious diseases (PSMA2, PSMC3, PSME2, NCKAP1, LTF, ENO1) and 10 immune-related proteins (the above-mentioned proteins, as well as CCT2, APOB, FGB, CA1, STOM). Thus, it is necessary to continue close examination of the mechanisms underlying this relationship in the interest of ensuring spaceflight medical safety.

Control of zoonotic infections common in animals and humans profoundly contributes to maintaining public health. The source of pathogens for humans is primarily presented by those animals with which they frequently come into contact during agricultural work, hunting, and gathering mushrooms or wild berries as well as in domestic settings (dogs, cats, other domestic animals, rodents). The study was conducted by the Center of New Medical Technologies, Novosibirsk, and involved 111 healthy volunteers. The specific immune response against the following zoonoses was analyzed: toxocariasis, toxoplasmosis, brucellosis, listeriosis, leptospirosis, and opisthorchiasis, based on specific IgG antibodies. Specific parasitic immune response was compared with the clinical data of the participants and blood IgE levels. Thirty-nine (35%) out of 111 participants had anti-parasitic IgG antibodies against the following zoonoses: leptospirosis, listeriosis, toxocariasis, toxoplasmosis, and opisthorchiasis. Among these 39 participants, 11 had antibodies specific to two or more zoonoses comprising 10% of the cohort. The IgE vs IgG level in the presence of any zoonosis significantly differed (p = 0.0001). Forty-seven participants had normal IgE levels, of whom 8 (17%) had IgG antibodies specific to one of the studied zoonoses. Sixty-four participants had elevated IgE levels, of whom 31 (48%) had IgG antibodies specific to one or more zoonoses, p = 0.001. The IgE level may be a predictor of the zoonoses in apparently healthy individuals at IgE level > 0.226 IU (area under the curve 0.73 [0.62–0.83], p = 0.0001; sensitivity 76%, specificity 62%). The identified diagnostic criteria for screening zoonoses can accelerate the differential diagnosis for conditions associated with non-specific complaints. Prospective randomized studies are needed to identify early pathology-related diagnostic criteria.

Background. The current study was designed to determine antibiotic resistance profile,detection of antimicrobial resistance and virulence-related genes among enterococcus species. Materials and methods. Altogether, one hundred fifty enterococcal isolates were collected from various clinical specimens and identified by Polymerase chain reaction (PCR). Antibiotic susceptibility testing and MICs of vancomycin were carried out as per CLSI guidelines. A series of PCR reactions were used to screen vancomycin-resistant genes (vanA, vanB, and vanD) and virulence-related genes (esp, ace, asa1, gelE & cylA) among VRE enterococcus species. Results. The isolated enterococcal strains comprised 62.6% E. faecalis, 33.4% E. faecium, and 4% of other species. Overall enterococcus showed a high level of resistance; 94% to erythromycin, followed by ciprofloxacin 82.6%, levofloxacin 70%, and vancomycin 16%. The 57.4% of the isolates were recovered from hospitalized patients and 96% of the enterococcus isolates were multi-drug resistant. The MICs of vancomycin-resistant strains remained in the range of 32 µg/ml to 256 µg/ml for the majority of the isolates. The vancomycin-resistant phenotypes vanA, vanB, and vanD were found in 29.2%, 37.5%, and 33.3% isolates respectively. Regarding virulence determinants the observed percentages were as follows; esp: 16.6%, asa1: 70.8%, gelE: 25%, ace: 33.3%, and cylA: 25%. Conclusion. The majority of the isolates were E. faecalis and multi-drug resistant. The VRE isolates carried antimicrobial resistance and virulence-related genes, and vanA, B, D phenotypes were the most common among VRE isolates.

Pathogens, particularly Brucella spp., pose a serious threat to human and animal health. In the complex of anti-epidemic and sanitary-hygienic measures aimed at preventing infectious diseases, chemical disinfection plays an important role. This disinfection method is one of the effective, reliable and common ways to combat pathogenic biological agents. An important role is played by modern quaternary ammonium compounds (QAC)-based disinfectants. In relation to chemical disinfectants, the causative agent of brucellosis belongs to the group of low-resistant microorganisms. Solutions of sublimate, creolin, phenol, sulfuric, hydrochloric, nitric and acetic acids, formalin, chloramine, hydrogen peroxide, solutions of disinfectants based on QAC, triamine and polyhexamethylene guanidine (PHMG) have pronounced bactericidal activity against brucellae. However, the instructions for commercial disinfectants note a bactericidal activity against pathogens of particularly dangerous infections (plague, tularemia, cholera and anthrax), but do not indicate antimicrobial properties against Brucella. The purpose of the work was to determine the antimicrobial properties of five commercial disinfectants “Alfadez Forte”, “Aminaz-Plus”, “Veltolen”, “Desarin” and “Laina-med”, used in the disinfection of objects with especially dangerous infections of bacterial etiology. The studies were carried out using the suspension method, according to the manual “Methods of laboratory research and testing of disinfectants to assess their effectiveness and safety”. Three vaccine strains B. melitensis Rev-1, B. abortus 19 BA, B. suis 61 were used as test microbes. As a result of the studies, it was found that commercial disinfectants “Alfadez Forte”, “Aminaz-Plus”, “Veltolen”, “Desarin” and “Lina-med” in the concentrations proposed by the manufacturers in the instructions for use when working with particularly dangerous infections (plague, tularemia, cholera) have bactericidal properties relative to vaccine strains.

Streptococcus equinus is a non-enterococcal group D Streptococcus, Gram positive, non-hemolytic, lactic acid bacterium. The incidence of colonization in humans increases in rural areas, where there is high risk of exposure to animal feces and fermented food products. It is associated with specific diseases, such as osteoarticular infections, meningitis, biliary infections, infective endocarditis and colorectal cancer. A male 10-year-old patient, asymptomatic, without underlying medical conditions, was referred for routine check-up at the Outpatient Pediatric Clinic of the Nikea General Hospital, Piraeus, Greece. According to patient history, he had spent two weeks at a summer camp, where he had direct contact with horses, such as horse riding, horse feeding, watering, horse care, etc. His brother, although he had the same contacts and activities, did not present an infection. Examinations of the eyes, mouth, ears, nose, throat and abdomen were normal. Laboratory tests showed mild leukocytosis (12 000/mm³, with 80% neutrophils) and slightly increased erythrocyte sedimentation rate (30 mm/h). Urinalysis and microscopy revealed bacteriuria by nitrite test and pyuria, so urine cultures were performed (Multistix 10 SG Reagent Strips, Siemens Healthineers). The urine culture grew monomicrobial S. equinus > 10⁵ CFU/ml. The bacterium was identified by the RapID™ REMEL ONE identification system (Thermo Fisher Scientific). Antimicrobial susceptibility testing revealed resistance to Clindamycin, Tetracycline, Cefotaxime and high susceptibility to Erythromycin. The patient received treatment with Erythromycin. Streptococcus equinus has been isolated from the bowel in approximately 7% of the general population. Urinary tract infections are less common. Risk factors for human colonization are considered living in rural areas and having contact with animal feces. The patient, during his stay at the summer camp, had probably contact with horse feces during the relevant activities and therefore infected.