Evaluation of expression and titration of recombinant nucleocapsid protein as an immunogenic candidate against SARS-CoV2

Introduction: Covid-19 epidemic results from an infection caused by SARS-CoV2. Evolution-based analyses on the nucleotide sequences show that SARS-CoV2 is a member of the genus Beta-coronaviruses and its genome consists of a single-stranded RNA, encoding 16 proteins. Among the structural proteins, the nucleocapsid is the most abundant protein in virus structure, highly immunogenic, with sequence conservatory. Due to a large number of mutations in the spike protein, the aim of this study was to investigate bioinformatics, expression of nucleocapsid protein and evaluate its immunogenicity as an immunogenic candidate. Materials and Methods: B and T cell epitopes of nucleocapsid protein were examined in the IEDB database. The PET28a-N plasmid was transferred to E. coli BL21(DE3) expression host, and IPTG induced recombinant protein expression. The protein was purified using Ni-NTA column affinity chromatography, and the Western blotting method was utilized to confirm it. Finally, mice were immunized with three routes of purified protein. Statistical analysis of the control group injection and test results was carried out by t-test from SPSS software. Results: The optimized gene had a Codon adaptation index (CAI) of 0/97 Percentage of codons having high- frequency distribution was improved to 85%. Expression of recombinant protein in E. coli led to the production of BoNT/B-HCC with a molecular weight of 45 kDa. The total yield of purified protein was 43 mg/L. Immunization of mice induced serum antibody response. Statistical analysis showed that the antibody titer ratio was significantly different compared to the control sample and the antibody titer was acceptable up to a dilution of 1.256000. Conclusion: According to the present study results, the protein can be used as an immunogenic candidate for developing vaccines against SARS-CoV2 in future research.

FEATURES OF POST-VACCINATION HUMORAL IMMUNE RESPONSE IN THE PERSONS WHO UNDERWENT COVID-19 OF VARIOUS SEVERITY.

The studies on humoral immune response in the individuals who have undergone COVID-19 and vaccinated with anti-COVID vaccines allows us to assess the development of "hybrid" immunity, which contributes to understanding the mechanisms of its formation from the effector phase to the step of immunological memory. We assessed the relative and absolute contents of B cell populations and subpopulations, development of humoral immunity in the patients who suffered with COVID-19 of varying severity being thereafter vaccinated with "KoviVak" and "Sputnik V". The study involved volunteers (age 47.3+/-14.5 years) who beared COVID-19 asymptomatically (n = 32), at moderate severity (n = 21), or had severe form of the disease (n = 12), then being vaccinated with "KoviVak" and "Sputnik V" 6-9 months after their recovery. The groups of vaccinated persons consisted of those who beared severe disease being vaccinated with "KoviVak" (n = 6) or "Sputnik V" (n = 6);moderate cases, vaccinated with "KoviVak" (n = 10) and "Sputnik V" (n = 11);asymptomatic cases vaccinated with "KoviVak" (n = 10) and "Sputnik V" (n = 22). We have determined relative and absolute numbers of B lymphocytes (CD45+CD19+), B1 lymphocytes (CD45+CD5+CD19-CD27-), B2 lymphocytes (CD45+CD19+CD5-CD27-), total population of memory B cells (CD45+CD19+CD5-CD27+), non-switched (CD45+CD19+IgD+CD27+), and switched (CD45+CD19+IgD-CD27+) memory B cells;mature naive B lymphocytes (CD45+CD19+CD27-IgD+), plasmoblasts (CD45+CD19+ CD38+++IgD-CD27+), as well as presence of IgG to S(RBD)-SARS-CoV-2 protein. We have found that the humoral immunity among survivors of COVID-19 of varying severity is expressed for up to nine months. The largest number of volunteers who raised antibodies to SARS-CoV-2 S-protein was registered in the group of seriously ill patients. As soon as 1 month after "Sputnik V" vaccination and until the end of the observation, all the examined subjects in this group became seropositive. 4-5 months after injection of this vaccine, specific immunoglobulins were present in all patients who had asymptomatic or average-severity infection. All volunteers who received "KoviVak" had antibodies to the COVID-19 viral S protein from the beginning to the end of the study. Vaccination, especially with "KoviVak", contributed to the highest increase, both in relative and absolute numbers of memory B lymphocytes in asymptomatic patients. Less pronounced changes in the content of B lymphocytes in COVID-19 patients who had severe and moderate clinical course may be associated with higher levels of these cells prior to injection of the vaccines. A positive correlation was found between the number of memory B cells and presence of immunoglobulins to the S protein SARS-CoV-2 in all examined patients.Copyright © 2023 Russian Association of Allergologists and Clinical Immunologists, St. Petersburg Regional Branch (SPb RAACI). All rights reserved.

In This Issue

The article presents highlights from this issue of the publisher. Topics include information on Systemic lupus erythematosus and its response to Rituximab, durable treatment for Antineutrophilic cytoplasmic antibody associated vasculitis, and earlier recognition of immune checkpoint inhibitors induced inflammatory arthritis.

Alterations in immunophenotype and metabolic profile of mononuclear cells during follow up in children with multisystem inflammatory syndrome (MIS-C).

Introduction: Although children seem to be less susceptible to COVID-19, some of them develop a rare but serious hyperinflammatory condition called multisystem inflammatory syndrome in children (MIS-C). While several studies describe the clinical conditions of acute MIS-C, the status of convalescent patients in the months after acute MIS-C is still unclear, especially the question of persistence of changes in the specific subpopulations of immune cells in the convalescent phase of the disease. Methods: We therefore analyzed peripheral blood of 14 children with MIS-C at the onset of the disease (acute phase) and 2 to 6 months after disease onset (post-acute convalescent phase) for lymphocyte subsets and antigen-presenting cell (APC) phenotype. The results were compared with six healthy age-matched controls. Results: All major lymphocyte populations (B cells, CD4 + and CD8+ T cells, and NK cells) were decreased in the acute phase and normalized in the convalescent phase. T cell activation was increased in the acute phase, followed by an increased proportion of γ/δ-double-negative T cells (γ/δ DN Ts) in the convalescent phase. B cell differentiation was impaired in the acute phase with a decreased proportion of CD21 expressing, activated/memory, and class-switched memory B cells, which normalized in the convalescent phase. The proportion of plasmacytoid dendritic cells, conventional type 2 dendritic cells, and classical monocytes were decreased, while the proportion of conventional type 1 dendritic cells was increased in the acute phase. Importantly the population of plasmacytoid dendritic cells remained decreased in the convalescent phase, while other APC populations normalized. Immunometabolic analysis of peripheral blood mononuclear cells (PBMCs) in the convalescent MIS-C showed comparable mitochondrial respiration and glycolysis rates to healthy controls. Conclusions: While both immunophenotyping and immunometabolic analyzes showed that immune cells in the convalescent MIS-C phase normalized in many parameters, we found lower percentage of plasmablasts, lower expression of T cell co-receptors (CD3, CD4, and CD8), an increased percentage of γ/δ DN Ts and increased metabolic activity of CD3/CD28-stimulated T cells. Overall, the results suggest that inflammation persists for months after the onset of MIS-C, with significant alterations in some immune system parameters, which may also impair immune defense against viral infections.

Reactogenicity and immunogenicity of the second COVID-19 vaccination in patients with inborn errors of immunity or mannan-binding lectin deficiency.

Background: Patients with inborn errors of immunity (IEI) are at increased risk for severe courses of SARS-CoV-2 infection. COVID-19 vaccination provides effective protection in healthy individuals. However, it remains unclear whether vaccination is efficient and safe in patients with constitutional dysfunctions of the immune system. Thus, we analyzed the humoral response, adverse reactions and assessed the disease activity of the underlying disease after COVID-19 vaccination in a cohort of patients suffering from IEIs or mannan-binding lectin deficiency (MBLdef). Methods: Vaccination response was assessed after basic immunization using the Elecsys anti-SARS-CoV-2 S immunoassay and via Vero E6 cell based assay to detect neutralization capabilities. Phenotyping of lymphocytes was performed by flow cytometry. Patient charts were reviewed for disease activity, autoimmune phenomena as well as immunization status and reactogenicity of the vaccination. Activity of the underlying disease was assessed using a patient global numeric rating scale (NRS). Results: Our cohort included 11 individuals with common variable immunodeficiency (CVID), one patient with warts hypogammaglobulinemia immunodeficiency myelokathexis (WHIM) syndrome, two patients with X-linked agammaglobulinemia (XLA), one patient with Muckle Wells syndrome, two patients with cryopyrin-associated periodic syndrome, one patient with Interferon-gamma (IFN-gamma) receptor defect, one patient with selective deficiency in pneumococcal antibody response combined with a low MBL level and seven patients with severe MBL deficiency. COVID-19 vaccination was generally well tolerated with little to no triggering of autoimmune phenomena. 20 out of 26 patients developed an adequate humoral vaccine response. 9 out of 11 patients developed a T cell response comparable to healthy control subjects. Tested immunoglobulin replacement therapy (IgRT) preparations contained Anti-SARS-CoV-2 S antibodies implicating additional protection through IgRT. Summary: In summary the data support the efficacy and safety of a COVID-19 vaccination in patients with IEIs/MBLdef. We recommend evaluation of the humoral immune response and testing for virus neutralization after vaccination in this cohort.

FEATURES OF POST-VACCINATION HUMORAL IMMUNE RESPONSE IN THE PERSONS WHO UNDERWENT COVID-19 OF VARIOUS SEVERITY.

The studies on humoral immune response in the individuals who have undergone COVID-19 and vaccinated with anti-COVID vaccines allows us to assess the development of "hybrid" immunity, which contributes to understanding the mechanisms of its formation from the effector phase to the step of immunological memory. We assessed the relative and absolute contents of B cell populations and subpopulations, development of humoral immunity in the patients who suffered with COVID-19 of varying severity being thereafter vaccinated with "KoviVak" and "Sputnik V". The study involved volunteers (age 47.3+/-14.5 years) who beared COVID-19 asymptomatically (n = 32), at moderate severity (n = 21), or had severe form of the disease (n = 12), then being vaccinated with "KoviVak" and "Sputnik V" 6-9 months after their recovery. The groups of vaccinated persons consisted of those who beared severe disease being vaccinated with "KoviVak" (n = 6) or "Sputnik V" (n = 6);moderate cases, vaccinated with "KoviVak" (n = 10) and "Sputnik V" (n = 11);asymptomatic cases vaccinated with "KoviVak" (n = 10) and "Sputnik V" (n = 22). We have determined relative and absolute numbers of B lymphocytes (CD45+CD19+), B1 lymphocytes (CD45+CD5+CD19-CD27-), B2 lymphocytes (CD45+CD19+CD5-CD27-), total population of memory B cells (CD45+CD19+CD5-CD27+), non-switched (CD45+CD19+IgD+CD27+), and switched (CD45+CD19+IgD-CD27+) memory B cells;mature naive B lymphocytes (CD45+CD19+CD27-IgD+), plasmoblasts (CD45+CD19+ CD38+++IgD-CD27+), as well as presence of IgG to S(RBD)-SARS-CoV-2 protein. We have found that the humoral immunity among survivors of COVID-19 of varying severity is expressed for up to nine months. The largest number of volunteers who raised antibodies to SARS-CoV-2 S-protein was registered in the group of seriously ill patients. As soon as 1 month after "Sputnik V" vaccination and until the end of the observation, all the examined subjects in this group became seropositive. 4-5 months after injection of this vaccine, specific immunoglobulins were present in all patients who had asymptomatic or average-severity infection. All volunteers who received "KoviVak" had antibodies to the COVID-19 viral S protein from the beginning to the end of the study. Vaccination, especially with "KoviVak", contributed to the highest increase, both in relative and absolute numbers of memory B lymphocytes in asymptomatic patients. Less pronounced changes in the content of B lymphocytes in COVID-19 patients who had severe and moderate clinical course may be associated with higher levels of these cells prior to injection of the vaccines. A positive correlation was found between the number of memory B cells and presence of immunoglobulins to the S protein SARS-CoV-2 in all examined patients.Copyright © 2023 Russian Association of Allergologists and Clinical Immunologists, St. Petersburg Regional Branch (SPb RAACI). All rights reserved.

Metabolomic Profiling of Lungs from Mice Reveals the Variability of Metabolites in Pneumocystis Infection and the Metabolic Abnormalities in BAFF-R-Deficient Mice.

Purpose: The incidence of Pneumocystis pneumonia (PCP) in patients without human immunodeficiency virus (HIV) has been increasing. In this study, we aimed to investigate the metabolic changes in Pneumocystis infection and the metabolic abnormalities in B-cell-activating factor receptor (BAFF-R)-deficient mice with Pneumocystis infection. Methods: The important function of B cells during Pneumocystis infection is increasingly recognized. In this study, a Pneumocystis-infected mouse model was constructed in BAFF-R-/- mice and wild-type (WT) mice. Lungs of uninfected WT C57BL/6, WT Pneumocystis-infected, and BAFF-R-/- Pneumocystis-infected mice were used for metabolomic analyses to compare the metabolomic profiles among the groups, with the aim of exploring the metabolic influence of Pneumocystis infection and the influence of mature B-cell deficiency during infection. Results: The results indicated that many metabolites, mainly lipids and lipid-like molecules, were dysregulated in Pneumocystis-infected WT mice compared with uninfected WT C57BL/6 mice. The data also demonstrated significant changes in tryptophan metabolism, and the expression levels of key enzymes of tryptophan metabolism, such as indoleamine 2,3-dioxygenase 1 (IDO1), were significantly upregulated. In addition, B-cell development and function might be associated with lipid metabolism. We found a lower level of alitretinoin and the abnormalities of fatty acid metabolism in BAFF-R-/- Pneumocystis-infected mice. The mRNA levels of enzymes associated with fatty acid metabolism in the lung were upregulated in BAFF-R-/- Pneumocystis-infected mice and positively correlated with the level of IL17A, thus suggesting that the abnormalities of fatty acid metabolism may be associated with greater inflammatory cell infiltration in the lung tissue of BAFF-R-/- Pneumocystis-infected mice compared with the WT Pneumocystis-infected mice. Conclusion: Our data revealed the variability of metabolites in Pneumocystis-infected mice, suggesting that the metabolism plays a vital role in the immune response to Pneumocystis infection.

Prospective Analysis of B Lymphocyte Subtypes, before and after Initiation of Dialysis, in Patients with End-Stage Renal Disease.

End-stage renal disease (ESRD) is followed by alterations in adaptive immunity. The aim of this study was to evaluate B lymphocyte subtypes in ESRD patients before and after hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD). PATIENTS AND METHODS: CD5, CD27, BAFF, IgM and annexin were evaluated by flow cytometry on CD19+ cells in ESRD patients (n = 40), at time of initiating HD or CAPD (T0) and 6 months later (T6). RESULTS: A significant reduction in ESRD-T0 compared to controls was noticed for CD19+, 70.8 (46.5) vs. 171 (249), p < 0.0001, CD19+CD5-, 68.6 (43) vs. 168.9 (106), p < 0.0001, CD19+CD27-, 31.2 (22.1) vs. 59.7 (88.4), p < 0.0001, CD19+CD27+, 42.1 (63.6) vs. 84.3 (78.1), p = 0.002, CD19+BAFF+, 59.7 (37.8) vs. 127.9 (123.7), p < 0.0001 and CD19+IgM+ cells, 48.9 (42.8) vs. 112.5 (81.7) (K/µL), p < 0.0001. The ratio of early/late apoptotic B lymphocytes was reduced (16.8 (10.9) vs. 110 (25.4), p = 0.03). CD19+CD5+ cells were the only cell type with an increased proportion in ESRD-T0 patients (2.7 (3.7) vs. 0.6 (1.1), p < 0.0001). After 6 months on CAPD or HD, CD19+CD27-(%) and early apoptotic lymphocytes were reduced further. The HD patients also showed a significant increase in late apoptotic lymphocytes, from 1.2 (5.7) to 4.2 (7.2) K/mL, p = 0.02. CONCLUSIONS: B cells and most of their subtypes were significantly reduced in ESRD-T0 patients compared to controls, the only exception being CD19+CD5+ cells. Apoptotic changes were prominent in ESRD-T0 patients and were exacerbated by HD.

A flow cytometric evaluation of B lymphocyte cells and subgroups of children diagnosed with COVID-19

Objective: During viral infections, antibody production of B cells are critical for protective immunity. It is known that the COVID-19 disease has a milder course in children. It is crucial to evaluate the causes of this situation from a pediatrician's perspective to determine the treatment goals of the disease. We aimed to examine the flow cytometric changes in B cells and subtypes observed in children diagnosed with the COVID-19 infection. Materials and Methods: This is a prospective cohort study including 22 children aged 0-18 who had been diagnosed with COVID-19. CD19+B cells, CD27- IgD+ naive B, CD21low immature B, CD21lowCD38low active B, CD27- IgD- double-negative B, CD27- non-memory B, CD27+ memory B, CD27+IgD- switched memory B, and CD27+IgD+ non-switched memory B cells were studied using flow cytometry. Results: B cells counts decreased as a percentage in the 2-5 years age group and the 10-16 age group as an absolute number. Naive and non-memory B cell frequencies increased in the 5-10 years old and over 16 years old groups. Double negative B cells were normal in all age groups. Non-memory B cells increased in the 5-10 and over 16 years old groups, whereas memory B cells decreased. In all groups, switched memory B cells decreased. Non-switched memory B cell counts were within reference ranges in all groups except for the over 16 years group. Conclusion: Although the decrease in B cell count is associated with the severity of the disease, naive B cell subgroups did not decrease in the pediatric patients included in the study. All groups showed increased switched memory B cell counts, in accordance with the literature. Unlike adults, naive B cells, non-switched memory B cells, and double-negative B cells were normal in children.

Evolutive emergence and divergence of an Ig regulatory node: An environmental sensor getting cues from the aryl hydrocarbon receptor?

One gene, the immunoglobulin heavy chain (IgH) gene, is responsible for the expression of all the different antibody isotypes. Transcriptional regulation of the IgH gene is complex and involves several regulatory elements including a large element at the 3' end of the IgH gene locus (3'RR). Animal models have demonstrated an essential role of the 3'RR in the ability of B cells to express high affinity antibodies and to express different antibody classes. Additionally, environmental chemicals such as aryl hydrocarbon receptor (AhR) ligands modulate mouse 3'RR activity that mirrors the effects of these chemicals on antibody production and immunocompetence in mouse models. Although first discovered as a mediator of the toxicity induced by the high affinity ligand 2,3,7,8-tetracholordibenzo-p-dioxin (dioxin), understanding of the AhR has expanded to a physiological role in preserving homeostasis and maintaining immunocompetence. We posit that the AhR also plays a role in human antibody production and that the 3'RR is not only an IgH regulatory node but also an environmental sensor receiving signals through intrinsic and extrinsic pathways, including the AhR. This review will 1) highlight the emerging role of the AhR as a key transducer between environmental signals and altered immune function; 2) examine the current state of knowledge regarding IgH gene regulation and the role of the AhR in modulation of Ig production; 3) describe the evolution of the IgH gene that resulted in species and population differences; and 4) explore the evidence supporting the environmental sensing capacity of the 3'RR and the AhR as a transducer of these cues. This review will also underscore the need for studies focused on human models due to the premise that understanding genetic differences in the human population and the signaling pathways that converge at the 3'RR will provide valuable insight into individual sensitivities to environmental factors and antibody-mediated disease conditions, including emerging infections such as SARS-CoV-2.

B Cell Reconstitution is Associated With COVID-19 Booster Vaccine Responsiveness in Patients Previously Seronegative Treated With Rituximab.

OBJECTIVE: To assess factors associated with serologic response to the coronavirus 2019 (COVID-19) booster vaccine in patients with autoimmune rheumatic diseases treated with rituximab (RTX) who were previously serologically unresponsive to the initial vaccine series. METHODS: A retrospective chart review of patients treated with RTX who failed to demonstrate a serologic response to the first SARS-CoV-2 vaccination series and subsequently received an mRNA vaccine booster was performed. Serologic response ≥ 4 weeks after the booster was the primary outcome. Fisher exact tests, t tests, and Wilcoxon rank-sum tests were used for comparisons. RESULTS: In 31 patients who were previously seronegative, 68% seroconverted following a booster of the COVID-19 vaccine. B cell reconstitution was significantly different between those with positive (median 1.79, IQR 0.65-3.00) and negative (median 0, IQR 0-0) serologic responses to the booster. The days from last RTX dose were also statistically different among seroconverters (median 301, IQR 251-368) vs nonseroconverters (median 188, IQR 169-245). Demographic characteristics were not associated with serologic positivity. Positive predictive value of B cell presence was 90.9% (95% CI 70.8-98.9) and negative predictive value was 100% (95% CI 59-100) for serologic response to the mRNA booster vaccine. Positive predictive value of time ≥ 6 months from last RTX dose to booster was 78.3% (95% CI 56.3-92.5) and the negative predictive value was 62.5% (95% CI 24.5-91.5). CONCLUSION: Detectable B cells and longer time from last RTX exposure were associated with the development of anti-SARS-CoV-2 spike protein antibodies following the booster vaccine. These findings should be considered in timing boosters in patients treated with RTX.

Distinct platelet crosstalk with adaptive and innate immune cells after adenoviral and mRNA vaccination against SARS-CoV-2.

BACKGROUND: Genetic-based COVID-19 vaccines have proved to be highly effective in reducing the risk of hospitalization and death. Because they were first distributed in a large-scale population, the adenoviral-based vaccines were linked to a very rare thrombosis with thrombocytopenia syndrome, and the interplay between platelets and vaccinations increasingly gained attention. OBJECTIVES: The objective of this article was to study the crosstalk between platelets and the vaccine-induced immune response. METHODS: We prospectively enrolled young healthy volunteers who received the mRNA-based vaccine, BNT162b2 (n = 15), or the adenovirus-based vaccine, AZD1222 (n = 25) and studied their short-term platelet and immune response before and after vaccine injections. In a separate cohort, we retrospectively analyzed the effect of aspirin on the antibody response 1 and 5 months after BNT162b2 vaccination. RESULTS: Here, we show that a faster antibody response to either vaccine is associated with the formation of platelet aggregates with marginal zone-like B cells, a subset geared to bridge the temporal gap between innate and adaptive immunities. However, although the mRNA-based vaccine is associated with a more gradual and tolerogenic response that fosters the crosstalk between platelets and adaptive immunity, the adenovirus-based vaccine, the less immunogenic of the 2, evokes an antiviral-like response during which the platelets are cleared and less likely to cooperate with B cells. Moreover, subjects taking aspirin (n = 56) display lower antibody levels after BNT162b2 vaccination compared with matched individuals. CONCLUSION: Platelets are a component of the innate immune pathways that promote the B-cell response after vaccination. Future studies on the platelet-immune crosstalk post-immunization will improve the safety, efficacy, and strategic administration of next-generation vaccines.

CD19+ B cell values predict the increase of anti-SARS CoV2 antibodies in fingolimod-treated and COVID-19-vaccinated patients with multiple sclerosis.

BACKGROUND: Treatment with fingolimod for multiple sclerosis (MS) reduces the efficacy of COVID-19 vaccination. The aim of this exploratory study was to evaluate whether main lymphocyte subsets and demographic features correlated to the subsequent increase in anti-SARS-CoV2 antibodies following the third dose of COVID-19 vaccination in fingolimod-treated MS patients. METHODS: This was a prospective single-center observational exploratory study including a subgroup of adult patients with MS (pwMS) in treatment with fingolimod who underwent COVID-19 vaccination. The association of anti-SARS-CoV2 antibody levels (reported as the Log10 of the difference between the post and pre third dose levels) with the total number and percentage of CD3+ T and CD19+ B was assessed by a linear regression model adjusted for age and sex. RESULTS: We found that peripheral blood CD19+ B lymphocytes before the third dose of vaccination in pwMS treated with fingolimod predict the subsequent increase of anti-SARS-CoV2 antibodies. CONCLUSION: This work suggests that evaluating the percentage of CD19+ B cells may be important to identify patients at risk of not producing SARS-CoV-2 antibodies, with possible reduced protection from COVID-19.

Case series evaluating lymphocyte subgroups at diagnosis and after treatment in multisystem inflammatory syndrome associated with COVID-19 in children

Objective: In this case series, we aimed to examine the changes in lymphocyte subgroups in children diagnosed with the multisystem inflammatory syndrome (MIS-C) during the acute phase and in the first month after treatment. Material and Methods: Ethics committee approval was received for the study from the Ethics Committee of Ondokuz Mayis University patient data were analyzed from medical records in an electronic database. Initial immunological evaluations of our first five patients diagnosed with MIS-C were made, steroid and IVIG treatments were given to the patients, and lymphocyte subgroups were evaluated for the second time in the first month for control purposes.

Special Issue: SARS-CoV-2 immunity. (Special Issue: SARS-CoV-2 immunity.)

This special issue contains 9 review articles that discuss the biology of SARS-CoV-2 infection, focusing on the immunological aspects to the disease, immunity to this pathogen, and production of life-saving vaccines. The following areas are given special attention: the creation of a system of biospecimen sample collection, antiviral functions of interferon family members, diversity of SARS-COV-2-specific B cells, inflammatory response and mucosal immunity, the importance of taking sex into account as a biological variable in susceptibility to infectious disease, paediatric SARS-CoV-2 infection and the importance of early life SARS-CoV-2 vaccination, and the immune response to tuberculosis both before and during the pandemic.

Universal nature of cholinergic regulation demonstrated with nicotinic acetylcholine receptors.

Mammalian nicotinic acetylcholine receptors (nAChRs) were initially discovered as ligand-gated ion channels mediating fast synaptic transmission in the neuro-muscular junctions and autonomic ganglia. They were further found to be involved in a wide range of basic biological processes within the brain and in non-excitable tissues. The present review summarizes the data obtained in our laboratory during last two decades. Investigation of autonomic ganglia with the nAChR subunit-specific antibodies was followed by identification of nAChRs in B lymphocytes, discovery of mitochondrial nAChRs and their role in mitochondrial apoptosis pathway, and revealing the role of α7 nAChRs and α7-specific antibodies in neuroinflammation-related Alzheimer disease and COVID-19. The data obtained demonstrate the involvement of nAChRs in cell survival, proliferation, cell-to-cell communication and inflammatory reaction. Together with the ability of nAChRs to function in both ionotropic and metabotropic way, these data illustrate the universal nature of cholinergic regulation mediated by nAChRs.

B-lymphocyte-guided retreatment contributes to establish good effectiveness and safety profile in MS patients treated with rituximab.

BACKGROUND: Rituximab is extensively used for multiple sclerosis (MS) treatment. However, the best dosage remains to be established. It has been proposed that retreatment could be guided by B lymphocyte (BL) percentages. OBJECTIVE: To establish the best BL value for retreatment with rituximab in MS and to confirm the safety and efficacy of this approach. METHODS: A prospective study was done with an exploratory cohort and a confirmatory cohort of MS patients treated with rituximab between 2017 and 2021. The first one comprised 10 MS patients with BL assessed every 3 months after rituximab infusion and retreatment done when BL values were ≥0.5%. The confirmatory cohort included 41 MS patients (41.5% women, 87.8% with secondary progressive MS, median age = 46.3 (interquartile range: 41.3-52.1) years, disease duration = 14.1 (9-19.6) years, EDSS score = 5.5 (4.0-6.5)). The confirmatory cohort was treated with rituximab following the pattern established in the exploratory cohort. RESULTS: In the exploratory cohort, ≥0.2% BL was established as the best value for retreatment because in most cases, a substantial increase of BL counts was preceded by initial values of 0.2-0.3%. In the confirmatory cohort, rituximab reduced the annualized relapse rate (ARR 0.56 vs. 0.125, p < 0.001), proportion of patients with appearance of new/enlarged T2 lesions (63.4% vs. 12.2%, p < 0.001), gadolinium-enhancing lesions (39% vs. 0%, p < 0.001), and confirmed disability progression (55% vs. 27.5%, p = 0.037). There were 22 patients (53.7%) who achieved NEDA-3. No patients had severe infections, and 10.7% cases had reduced IgG levels. CONCLUSION: Rituximab treatment guided by BL showed high effectiveness and a good safety profile for MS patients after one year of treatment.

Features of postinfectious immunity formation in a patient with common variable immune deficiency and severe COVID-19 course: a description of a clinical case

Background. Common variable immune deficiency (CVID) is a complicating comorbid background of COVID-19. Post-infectious immunity formation to SARS-CoV-2 during a pandemic is of particular relevance for such patients. Aim of the study - to present the features of the development of postinfectious humoral immune response in a patient with CVID. Material and methods. Patient K., 49 years old, the diagnosis of CVID verified at the age of 33, has been receiving regular replacement therapy with intravenous immunoglobulins for the last 10 years. After intrafamily contact and infection with SARS-CoV-2 due to the progressive deterioration of the clinical course of COVID-19, he was admitted to a monoinfection hospital. Results. During the treatment of the severe clinical case of COVID-19 a patient with CVID proved to be effective therapy combining anti-cytokine drugs and additional courses of replacement therapy with intravenous immunoglobulins. 6 weeks later from the development of the clinic, the patient was detected specific antibodies to SARS-CoV-2 antigens - IgM (CP 4.73) and IgG (43 BAU), in 4 months the corresponding parameters were 3.55 (CP IgM) and 487 BAU (CP IgG). Comparative analysis of immunophenotyping of the patient's B lymphocytes before the disease, during periods of early and late convalescence showed the dynamics of changes in the number of naive B-lymphocytes, unswitched and switched B-memory cells, plasmablasts, B-reg and B-lymphocytes expressing intercellular cooperation molecules. Conclusion. In the patient with CVID the development of a specific humoral immune response to SARS-CoV-2 after a COVID-19 infection is accompanied by an increase in the proportion of B-memory cells, increased maturation of B-lymphocytes, coordinated dynamics of B-cell suppression and activation parameters. Copyright © 2022 Authors. All rights reserved.