Large Extracellular Vesicles Derived from Natural Killer Cells Affect the Functions of Monocytes.

Communication between natural killer cells (NK cells) and monocytes/macrophages may play an important role in immunomodulation and regulation of inflammatory processes. The aim of this research was to investigate the impact of NK cell-derived large extracellular vesicles on monocyte function because this field is understudied. We studied how NK-cell derived large extracellular vesicles impact on THP-1 cells characteristics after coculturing: phenotype, functions were observed with flow cytometry. In this study, we demonstrated the ability of large extracellular vesicles produced by NK cells to integrate into the membranes of THP-1 cells and influence the viability, phenotype, and functional characteristics of the cells. The results obtained demonstrate the ability of large extracellular vesicles to act as an additional component in the immunomodulatory activity of NK cells in relation to monocytes.

Apoptotic Receptors and CD107a Expression by NK Cells in an Interaction Model with Trophoblast Cells.

Natural killer cells (NK cells) exert cytotoxicity towards target cells in several ways, including the expression of apoptosis-mediating ligands (TRAIL, FasL). In addition, NK cells themselves may be susceptible to apoptosis due to the expression of TRAIL receptors. These receptors include TRAIL-R1 (DR4), TRAIL-R2 (DR5), capable of inducing apoptosis, and TRAIL-R3 (DcR1), TRAIL-R4 (DcR2), the so-called "decoy receptors", which lack an intracellular domain initiating activation of caspases. Of particular interest is the interaction of uterine NK cells with cells of fetal origin, trophoblasts, which are potential targets for natural killer cells to carry out cytotoxicity. The aim of this work was to evaluate the expression of proapoptotic receptors and their ligands as well as CD107a expression by NK cells in a model of interaction with trophoblast cells. To evaluate NK cells, we used cells of the NK-92 line; cells of the JEG-3 line were used as target cells. The cytokines IL-1ß, IL-15, IL-18, TNFα, IL-10, TGFß and conditioned media (CM) of the first and third trimester chorionic villi explants were used as inducers. We established that cytokines changed the expression of apoptotic receptors by NK cells: in the presence of TNFα, the amount and intensity of Fas expression increased, while in the presence of TGFß, the amount and intensity of expression of the DR5 receptor decreased. Soluble chorionic villi factors alter the expression of TRAIL and FasL by NK-92 cells, which can reflect the suppression of the TRAIL-dependent mechanism of apoptosis in the first trimester and stimulating the Fas-dependent mechanism in the third trimester. In the presence of trophoblast cells, the expression of TRAIL and DcR1 by NK cells was reduced compared to intact cells, indicating an inhibitory effect of trophoblast cells on NK cell cytotoxicity. In the presence of chorionic villi CM and trophoblast cells, a reduced number of NK-92 cells expressing DR4 and DR5 was found. Therefore, soluble factors secreted by chorionic villi cells regulate the resistance of NK cells to death by binding TRAIL, likely maintaining their activity at a certain level in case of contact with trophoblast cells.

CXCR3-Expressing T Cells in Infections and Autoimmunity.

The chemokine receptor CXCR3 and its ligands (MIG/CXCL9, IP-10/CXCL10, and I-TAC/CXCL11) play a central role in the generation of cellular inflammation, both in the protective responses to invading pathogens, and in different pathological conditions associated with autoimmunity. It is worth noting that CXCR3 is highly expressed on innate and adaptive lymphocytes, as well as on various cell subsets that are localized in non-immune organs and tissues. Our review focuses exclusively on CXCR3-expressing T cells, including Th1, Th17.1, Tfh17, Tfh17.1, CXCR3+ Treg cells, and Tc1 CD8+ T cells. Currently, numerous studies have highlighted the role of CXCR3-dependent interactions in the coordination of inflammation in the peripheral tissues, both to increase recruitment of CD4+ and CD8+ T cells that upregulate inflammation, and also for recruitment of CXCR3+ T regulatory cells to dampen overexuberant responses. Understanding the role of CXCR3 and its ligands might help to apply them as new and effective therapeutic targets in a wide range of diseases.

Role of IL-27 in COVID-19: A Thin Line between Protection and Disease Promotion.

Cytokine storm is usually described as one of the main reasons behind COVID-associated mortality. Cytokines are essential protein molecules engaged in immune responses; they play a critical role in protection against infections. However, they also contribute to inflammatory reactions and tissue damage, becoming a double-edged sword in the context of COVID-19. Recent studies have suggested various cytokines and chemokines that play a crucial role in the immune response to SARS-CoV-2 infection. One such cytokine is interleukin 27 (IL-27), which has been found to be elevated in the blood plasma of patients with COVID-19. Within this study, we will explore the role of IL-27 in immune responses and analyze both the existing literature and our own prior research findings on this cytokine in the context of COVID-19. It affects a wide variety of immune cells. Regardless of the pathological process it is involved in, IL-27 is critical for upholding the necessary balance between tissue damage and cytotoxicity against infectious agents and/or tumors. In COVID-19, it is involved in multiple processes, including antiviral cytotoxicity via CD8+ cells, IgG subclass switching, and even the activation of Tregs.

Detection of Polioviruses Type 2 among Migrant Children Arriving to the Russian Federation from a Country with a Registered Poliomyelitis Outbreak.

The widespread use of the oral poliovaccine from Sabin strains (tOPV) radically reduced poliomyelitis incidence worldwide. However, OPV became a source of neurovirulent vaccine-derived polioviruses (VDPVs). Currently, circulating type 2 VDPVs (cVDPV2) are the leading cause of poliomyelitis. The novel OPV type 2 vaccine (nOPV2), based on genetically modified Sabin strain with increased genetic stability and reduced risk of cVDPV formation, has been used to combat cVDPV2 outbreaks, including one in Tajikistan in 2021. In order to identify the importation of cVDPV2 and nOPV2-derivates, stool samples from 12,127 healthy migrant children under 5 years of age arriving from Tajikistan were examined in Russia (March 2021-April 2022). Viruses were isolated in cell culture and identified via intratype differentiation RT-PCR, VP1 and whole-genome sequencing. cVDPV2 isolates closely related with the Tajikistan one were isolated from two children, and nOPV2-derived viruses were detected in specimens from 106 children from 37 regions of Russia. The duration of nOPV2 excretion ranged from 24 to 124 days post-vaccination. nOPV2 isolates contained 27 mutations per genome (0.36%) on average, with no critical genetic changes, which confirms the genetic stability of nOPV2 during field use. The possibility of epidemiologically significant poliovirus introduction into polio-free countries has been confirmed. The screening of special populations, including migrants, is required to maintain epidemiological well-being.

Vitamin D Metabolism Parameters and Cytokine Profile in COVID-19 Patients with Bolus Cholecalciferol Supplementation.

Recent studies have demonstrated the relationship between vitamin D deficiency, infection severity and mortality from COVID-19. This study aimed to analyze the vitamin D metabolites and cytokine expression levels of COVID-19 patients who were hospitalized with bolus cholecalciferol supplementation. MATERIALS AND METHODS: This study represents the next stage of the open-label randomized pilot conducted by the Almazov National Medical Research Centre. A total of 44 hospitalized patients, comparable in demographic, clinical, laboratory and instrumental baseline characteristics, with moderate/severe COVID-19 were included. All patients had similar doses of concomitant corticosteroid therapy. Twenty-two patients received 50,000 IU cholecalciferol on the first and eighth days of hospitalization. The serum 25(OH)D, 1,25(OH)2D and 28 plasma cytokines were estimated for each group initially and on the ninth day of hospitalization. RESULTS: Initially, there were no differences in the 1,25(OH)2D and cytokine levels in patients with vitamin D deficiency and normal 25(OH)D. Bolus cholecalciferol therapy at a total dose of 100,000 IU led to an increase in 25(OH)D levels in hospitalized patients with COVID-19, while the levels of the active metabolite (1,25(OH)2D) did not show significant differences between the groups or in its increased level over time, regardless of cholecalciferol supplementation. Furthermore, cholecalciferol supplementation at a total dose of 100,000 IU did not affect the majority of the cytokines estimated on the ninth day of hospitalization, except for the pro-inflammatory marker IL-1b, the concentration of which was lower in the group of patients without vitamin D supplementation. CONCLUSIONS: The 25(OH)D level was positively associated with an anti-inflammatory immune response, but cholecalciferol supplementation at a total dose of 100,000 IU did not affect the active-form vitamin D or cytokine expression levels. This fact may be explained by the impact of corticosteroid therapy, and it requires further investigation in a post-COVID-19 context.

Resistance Mutation Patterns among HIV-1-Infected Children and Features of the Program for Prevention of Mother-to-Child Transmission in Vietnam's Central Highlands and Southern Regions, 2017-2021.

The Vietnam Ministry of Health (MOH) has intensified efforts in its aim to eliminate AIDS by 2030. Expanding the program for prevention of mother-to-child transmission (PMTCT) is a significant step towards achieving this goal. However, there are still HIV-exposed children who do not have access to PMTCT services, and some who have participated in the program but still contracted HIV. This study focused on assessing the prevalence and profile of HIV mutations among children under 18 months of age who had recently tested positive for HIV, while gaining insights into the implementation of early infant diagnostic (EID) tests. Between 2017 and 2021, 3.43% of 5854 collected dry blood spot (DBS) specimens from Vietnam's Central and Southern regions showed positive EID results. This study identified a high prevalence of resistance mutations in children, totaling 62.9% (95% CI: 53.5-72.3). The highest prevalence of mutations was observed for NNRTIs, with 57.1% (95% CI: 47.5-66.8). Common mutations included Y181C and K103N (NNRTI resistance), M184I/V (NRTI resistance), and no major mutations for PI. The percentage of children with any resistance mutation was significantly higher among those who received PMTCT interventions (69.2%; 95% CI: 50.5-92.6%) compared with those without PMTCT (45.0%; 95% CI: 26.7-71.1%) with χ2 = 6.06, p = 0.0138, and OR = 2.75 (95% CI: 1.13-6.74). Mutation profiles revealed that polymorphic mutations could be present regardless of whether PMTCT interventions were implemented or not. However, non-polymorphic drug resistance mutations were predominantly observed in children who received PMTCT measures. Regarding PMTCT program characteristics, this study highlights the issue of late access to HIV testing for both mothers and their infected children. Statistical differences were observed between PMTCT and non-PMTCT children. The proportion of late detection of HIV infection and breastfeeding rates were significantly higher among non-PMTCT children (p < 0.05). Comparative analysis between children with low viral load (≤200 copies/mL) and high viral load (>200 copies/mL) showed significant differences between the mothers' current ART regimens (p = 0.029) and the ARV prophylaxis regimen for children (p = 0.016). These findings emphasize the need for comprehensive surveillance to assess the effectiveness of the PMTCT program, including potential transmission of HIV drug-resistance mutations from mothers to children in Vietnam.

COVID-19 Incidence Proportion as a Function of Regional Testing Strategy, Vaccination Coverage, and Vaccine Type.

Introduction: The COVID-19 pandemic has become a serious challenge for humanity almost everywhere globally. Despite active vaccination around the world, the incidence proportion in different countries varies significantly as of May 2022. The reason may be a combination of demographic, immunological, and epidemiological factors. The purpose of this study was to analyze possible relationships between COVID-19 incidence proportion in the population and the types of SARS-CoV-2 vaccines used in different countries globally, taking into account demographic and epidemiological factors. Materials and methods: An initial database was created of demographic and immunoepidemiological information about the COVID-19 situation in 104 countries collected from published official sources and repository data. The baseline included, for each country, population size and density; SARS-CoV-2 testing coverage; vaccination coverage; incidence proportion; and a list of vaccines that were used, including their relative share among all vaccinations. Subsequently, the initial data set was stratified by population and vaccination coverage. The final data set was subjected to statistical processing both in general and taking into account population testing coverage. Results: After formation of the final data set (including 53 countries), it turned out that reported COVID-19 case numbers correlated most strongly with testing coverage and the proportions of vaccine types used, specifically, mRNA (V1); vector (V2); peptide/protein (V3); and whole-virion/inactivated (V4). Due to the fact that an inverse correlation was found between 'reported COVID-19 case numbers' with V2, V3, and V4, these three vaccine types were also combined into one analytic group, 'non-mRNA group' vaccines (Vnmg). When the relationship between vaccine type and incidence proportion was examined, minimum incidence proportion was noted at V1:Vnmg ratios (%:%) from 0:100 to 30:70. Maximum incidence proportion was seen with V1:Vnmg from 80:20 to 100:0. On the other hand, we have shown that the number of reported COVID-19 cases in different countries largely depends on testing coverage. To offset this factor, countries with low and extremely high levels of testing were excluded from the data set; it was then confirmed that the largest number of reported COVID-19 cases occurred in countries with a dominance of V1 vaccines. The fewest reported cases were seen in countries with a dominance of Vnmg vaccines. Conclusion: In this paper, we have shown for the first time that the level of reported COVID-19 incidence proportion depends not only on SARS-CoV-2 testing and vaccination coverage, which is quite logical, but probably also on the vaccine types used. With the same vaccination level and testing coverage, those countries that predominantly use vector and whole-virion vaccines feature incidence proportion that is significantly lower than countries that predominantly use mRNA vaccines.

HIV Drug Resistance Mutations and Subtype Profiles among Pregnant Women of Ho Chi Minh City, South Vietnam.

According to the latest data released by UNAIDS, the global number of people living with HIV (PLHIV) in 2021 was 38.4 million, with 1.5 million new HIV infections. In different countries, a significant proportion of these cases occur in the adult fertile population aged 15-49 years. According to UNAIDS, Vietnam had a national HIV prevalence of 0.3% of the total population at the end of 2019, with approximately 230,000 PLHIV. The most effective way to prevent mother-to-child transmission of HIV is ART to reduce maternal viral load. HIV-infected pregnant women should undergo monthly monitoring, especially before the expected date of delivery. The aim of our work was to analyze subtypic structure and drug-resistant variants of HIV in pregnant women in Ho Chi Minh City. The study material was blood plasma samples from HIV-infected pregnant women: 31 women showed virological failure of ART, and 30 women had not previously received therapy. HIV-1 genotyping and mutation detection were performed based on analysis of the nucleotide sequences of the pol gene region. More than 98% of sequences genotyped as HIV-1 sub-subtype CRF01_AE. When assessing the occurrence of drug resistance mutations, genetic resistance to any drug was detected in 74.41% (95% CI: 62.71-85.54%) of patients. These included resistance mutations to protease inhibitors in 60.66% (95% CI: 47.31-72.93%) of patients, to NRTIs in 8.20% (95% CI: 2.72-18.10%), and to NNRTIs in 44.26% (95% CI: 31.55-57.52%). Mutations associated with NRTI (2) and NNRTI (8) resistance as well as PI mutations (12), including minor ones, were identified. The high prevalence of drug resistance mutations found in this study among pregnant women, both in therapeutically naive individuals and in patients with virological failure of ART, indicates that currently used regimens in Vietnam are insufficient to prevent vertical HIV infection.

Macrophage-Derived Chemokine MDC/CCL22: An Ambiguous Finding in COVID-19.

Macrophage-derived chemokine (MDC/CCL22) is a chemokine of the C-C subfamily. It is involved in T-cellular maturation and migration. Our previous research shows that plasma CCL22/MDC tends to show a statistically significant depletion of concentrations in acute patients and convalescents when compared to healthy donors. In the current work, we investigate existing views on MDC/CCL22 dynamics in association with various pathologies, including respiratory diseases and, specifically, COVID-19. Additionally, we present our explanations for the observed decrease in MDC/CCL22 concentrations in COVID-19. The first hypothesis we provide implies that viral products bind to MDC/CCL22 and block its activity. Another explanation for this phenomenon is based on dendritic cells population and the inhibition of their function.

Correction: Gladkikh et al. Epidemiological Features of COVID-19 in Northwest Russia in 2021. Viruses 2022, 14, 931.

There was an error in the original publication [...].

ATR-FTIR spectrum analysis of plasma samples for rapid identification of recovered COVID-19 individuals.

The development of fast, cheap and reliable methods to determine seroconversion against infectious agents is of great practical importance. In the context of the COVID-19 pandemic, an important issue is to study the rate of formation of the immune layer in the population of different regions, as well as the study of the formation of post-vaccination immunity in individuals after vaccination. Currently, the main method for this kind of research is enzyme immunoassay (ELISA, enzyme-linked immunosorbent assay). This technique is sufficiently sensitive and specific, but it requires significant time and material costs. We investigated the applicability of attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy associated with machine learning in blood plasma to detect seroconversion against SARS-CoV-2. The study included samples of 60 patients. Clear spectral differences in plasma samples from recovered COVID-19 patients and conditionally healthy donors were identified using multivariate and statistical analysis. The results showed that ATR-FTIR spectroscopy, combined with principal components analysis (PCA) and linear discriminant analysis (LDA) or artificial neural network (ANN), made it possible to efficiently identify specimens from recovered COVID-19 patients. We built classification models based on PCA associated with LDA and ANN. Our analysis led to 87% accuracy for PCA-LDA model and 91% accuracy for ANN, respectively. Based on this proof-of-concept study, we believe this method could offer a simple, label-free, cost-effective tool for detecting seroconversion against SARS-CoV-2. This approach could be used as an alternative to ELISA.

Fraction of plasma exomeres and low-density lipoprotein cholesterol as a predictor of fatal outcome of COVID-19.

Transcriptomic analysis conducted by us previously revealed upregulation of genes involved in low-density lipoprotein particle receptor (LDLR) activity pathway in lethal COVID-19 caused by SARS-CoV-2 virus (severe acute respiratory syndrome coronavirus 2). Last data suggested the possible role of extracellular vesicles in COVID-19 pathogenesis. The aim of the present study was to retrospectively evaluate parameters of cholesterol metabolism and newly identified EVs, exomeres, as possible predictors of fatal outcome of COVID-19 patients infected by the Alpha and the Delta variants of SARS-CoV-2 virus. Blood from 67 patients with severe COVID-19 were collected at the time of admission to the intensive care unit (ICU) and 7 days after admission to the ICU. After 30 days patients were divided into two subgroups according to outcome-34 non-survivors and 33 survivors. This study demonstrated that plasma low- and high-density lipoprotein cholesterol levels (LDL-C and HDL-C) were decreased in non-survivors compared to controls at the time of admission to the ICU. The conjoint fraction of exomeres and LDL particles measured by dynamic light scattering (DLS) was decreased in non-survivors infected by the Alpha and the Delta variants compared to survivors at the time of admission to the ICU. We first showed that reduction of exomeres fraction may be critical in fatal outcome of COVID-19.

Prevalence of HIV and Viral Hepatitis Markers among Healthcare Workers in the Republic of Guinea.

Healthcare workers are much more likely to be infected with HIV and hepatitis viruses compared to the general population. Although healthcare workers are more aware of HIV and hepatitis viruses, several countries in Africa lack a comprehensive grasp of disease routes and transmission risks. The aim of this study was to assess the prevalence of the serological and molecular biological markers of HIV and viral hepatitis among healthcare workers in the Republic of Guinea. The study material was 74 blood serum samples collected from healthcare workers who received additional training at the Institute of Applied Biological Research of Guinea (IRBAG, Kindia, Republic of Guinea). The markers examined included HBsAg, HBeAg, anti-HBs IgG, anti-HBcore IgG, anti-HCV qualitative determination, anti-HEV IgM and IgG, anti-HAV IgM and IgG, and anti-HIV. For viral DNA and RNA detection, nucleic acids were extracted from blood serum, and viral presence was inferred using real-time PCR with hybridization fluorescence detection. A high prevalence of viral hepatitis B markers was shown, and significantly fewer cases of viral hepatitis C and HIV were detected. Almost all examined medical workers had anti-HAV IgG antibodies, but no antibodies to hepatitis E virus. Apparently, the identified markers depend on the general prevalence of certain pathogens in the region and are associated with the traditions and characteristics of the country's residents.

Comparative Analysis of Library Preparation Approaches for SARS-CoV-2 Genome Sequencing on the Illumina MiSeq Platform.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been responsible for over two years of the COVID-19 pandemic and a global health emergency. Genomic surveillance plays a key role in overcoming the ongoing COVID-19 pandemic despite its relative successive waves and the continuous emergence of new variants. Many technological approaches are currently applied for the whole genome sequencing (WGS) of SARS-CoV-2. They differ in key stages of the process, and they feature some differences in genomic coverage, sequencing depth, and in the accuracy of variant-calling options. In this study, three different protocols for SARS-CoV-2 WGS library construction are compared: an amplicon-based protocol with a commercial primer panel; an amplicon-based protocol with a custom panel; and a hybridization capture protocol. Specific differences in sequencing depth and genomic coverage as well as differences in SNP number were found. The custom panel showed suitable results and a predictable output applicable for the epidemiological surveillance of SARS-CoV-2 variants.

Prevalence of drug resistant HIV-1 forms in patients without any history of antiretroviral therapy in the Republic of Guinea.

To study the structure of human immunodeficiency virus (HIV)-1 drug resistance (DR) in patients with newly diagnosed infection. Residents of the Republic of Guinea (N = 2168) were tested for HIV using enzyme-linked immunosorbent assay (ELISA). Individuals with a positive result were further examined for the presence of viral load in blood plasma. HIV was analyzed using Sanger sequencing. The obtained sequences were genotyped using REGA (version 3.0) and analyzed in MEGA 7. Analysis for the presence of DR mutations was performed using the Stanford University HIV DR Database. Serological markers of HIV were detected in 239 people, which represents 11.02% of the entire sample. HIV RNA was detected in 58 people. The following subtypes were seen: HIV CRF02_AG (41.9%); A1 (29.1%); A3 (12.9%); URF A1_G (12.9%); and G (3.2%). In 25% of patients, at least one significant mutation was encountered leading directly to HIV DR. The mutations encountered cause resistance to NRTI and NNRTI; one case of multiple resistance was identified. Major resistance to protease inhibitor was not seen. The detection of HIV-1 mutations associated with DR, in individuals who have never received antiretroviral therapy, is a cause for concern. It suggests that: new infections are occurring with strains that already have resistance; and the expansion of resistance is not always directly associated with selective drug pressure. Among the likely reasons for the high prevalence of primary HIV DR in the Republic of Guinea, drug availability is probably the key. The consequence of this is the lack of adherence of patients to treatment, the formation and transmission of resistant variants of the virus in the population. These findings suggest the need to test patients for resistant virus variants before initiating treatment.

Cytokine Profiling in Different SARS-CoV-2 Genetic Variants.

This study is a successor of our previous work concerning changes in the chemokine profile in infection that are associated with different SARS-CoV-2 genetic variants. The goal of our study was to take into account both the virus and the host immune system by assessing concentrations of cytokines in patients infected with different SARS-CoV-2 variants (ancestral Wuhan strain, Alpha, Delta and Omicron). Our study was performed on 340 biological samples taken from COVID-19 patients and healthy donors in the timespan between May 2020 and April 2022. We performed genotyping of the virus in nasopharyngeal swabs, which was followed by assessment of cytokines' concentration in blood plasma. We noted that out of nearly 30 cytokines, only four showed stable elevation independently of the variant (IL-6, IL-10, IL-18 and IL-27), and we believe them to be 'constant' markers for COVID-19 infection. Cytokines that were studied as potential biomarkers lose their diagnostic value as the virus evolves, and the specter of potential targets for predictive models is narrowing. So far, only four cytokines (IL-6, IL-10, IL-18, and IL-27) showed a consistent rise in concentrations independently of the genetic variant of the virus. Although we believe our findings to be of scientific interest, we still consider them inconclusive; further investigation and comparison of immune responses to different variants of SARS-CoV-2 is required.

HLA Genotypes in Patients with Infection Caused by Different Strains of SARS-CoV-2.

The aggressive infectious nature of SARS-CoV-2, its rapid spread, and the emergence of mutations necessitate investigation of factors contributing to differences in SARS-CoV-2 susceptibility and severity. The role of genetic variations in the human HLA continues to be studied in various populations in terms of both its effect on morbidity and clinical manifestation of illness. The study included 484 COVID-19 convalescents (northwest Russia residents of St. Petersburg). Cases in which the responsible strain was determined were divided in two subgroups: group 1 (n = 231) had illness caused by genovariants unrelated to variant of concern (VOC) strains; and group 2 (n = 80) had illness caused by the delta (B.1.617.2) VOC; and a control group (n = 1456). DNA typing (HLA-A, B, DRB1) was performed at the basic resolution level. HLA-A*02 was associated with protection against infection caused by non-VOC SARS-CoV-2 genetic variants only but not against infection caused by delta strains. HLA-A*03 was associated with protection against infection caused by delta strains; and allele groups associated with infection by delta strains were HLA-A*30, B*49, and B*57. Thus, in northwest Russia, HLA-A*02 was associated with protection against infection caused by non-VOC SARS-CoV-2 genetic variants but not against delta viral strains. HLA-A*03 was associated with a reduced risk of infection by delta SARS-CoV-2 strains. HLA-A*30, HLA-B*49, and HLA-B*57 allele groups were predisposing factors for infection by delta (B.1.617.2) strains.

Heterogenous CD8+ T Cell Maturation and 'Polarization' in Acute and Convalescent COVID-19 Patients.

BACKGROUND: The adaptive antiviral immune response requires interaction between CD8+ T cells, dendritic cells, and Th1 cells for controlling SARS-CoV-2 infection, but the data regarding the role of CD8+ T cells in the acute phase of COVID-19 and post-COVID-19 syndrome are still limited. METHODS: . Peripheral blood samples collected from patients with acute COVID-19 (n = 71), convalescent subjects bearing serum SARS-CoV-2 N-protein-specific IgG antibodies (n = 51), and healthy volunteers with no detectable antibodies to any SARS-CoV-2 proteins (HC, n = 46) were analyzed using 10-color flow cytometry. RESULTS: Patients with acute COVID-19 vs. HC and COVID-19 convalescents showed decreased absolute numbers of CD8+ T cells, whereas the frequency of CM and TEMRA CD8+ T cells in acute COVID-19 vs. HC was elevated. COVID-19 convalescents vs. HC had increased naïve and CM cells, whereas TEMRA cells were decreased compared to HC. Cell-surface CD57 was highly expressed by the majority of CD8+ T cells subsets during acute COVID-19, but convalescents had increased CD57 on 'naïve', CM, EM4, and pE1 2-3 months post-symptom onset. CXCR5 expression was altered in acute and convalescent COVID-19 subjects, whereas the frequencies of CXCR3+ and CCR4+ cells were decreased in both patient groups vs. HC. COVID-19 convalescents had increased CCR6-expressing CD8+ T cells. Moreover, CXCR3+CCR6- Tc1 cells were decreased in patients with acute COVID-19 and COVID-19 convalescents, whereas Tc2 and Tc17 levels were increased compared to HC. Finally, IL-27 negatively correlated with the CCR6+ cells in acute COVID-19 patients. CONCLUSIONS: We described an abnormal CD8+ T cell profile in COVID-19 convalescents, which resulted in lower frequencies of effector subsets (TEMRA and Tc1), higher senescent state (upregulated CD57 on 'naïve' and memory cells), and higher frequencies of CD8+ T cell subsets expressing lung tissue and mucosal tissue homing molecules (Tc2, Tc17, and Tc17.1). Thus, our data indicate that COVID-19 can impact the long-term CD8+ T cell immune response.

Method for hepatitis B virus DNA detecting in biological material at low viral load based on nested PCR with detection on three viral targets in real-time mode.

A method has been developed for HBV DNA finding in biological material at low viral load based on nested PCR with real-time detection of three viral targets. When developing the method, blood plasma samples were used from 128 CHB patients living in the regions of the Russian Federation and countries of Central Asia and 173 hemodialysis center patients living in the North-West Federal District. Analytical sensitivity was tested using the stepwise dilution method. HBV was detected by nested PCR. According to the method developed by us, at the first stage, the HBV DNA is amplified using at the first stage oligonucleotides complementary to the greatest similarity regions of the various HBV isolates genomes flanking the entire virus genome. At the second stage, when using the amplification product of the first stage as a template, PCR was performed using three pairs of oligonucleotides and the corresponding oligonucleotide fluorescently labeled probes to three virus genome regions (Core gene, S gene and X gene), as well as one pair of primers and the corresponding probe complementary to a human HPRT gene region. The method sensitivity for DNA extraction from plasma with a 100 µl volume was 10 IU/ml. Obtaining a threshold Ct cycle for only one fluorophore may indicate the presence of HBV DNA in the sample at a load of less than 10 IU/ml, HBV detection in this case is possible with a repeated PCR study of the corresponding sample with HBV DNA extraction from an increased plasma volume (200-1000 µl). The developed method makes it possible to identify the disease in various HBV subgenotypes and can be used to diagnose CHB in the population and risk groups, including those with the HBsAg-negative form of the disease.