Role of TAM Receptors in Antimalarial Humoral Immune Response.

Immune response against malaria and the clearance of Plasmodium parasite relies on germinal-center-derived B cell responses that are temporally and histologically layered. Despite a well-orchestrated germinal center response, anti-Plasmodium immune response seldom offers sterilizing immunity. Recent studies report that certain pathophysiological features of malaria such as extensive hemolysis, hypoxia as well as the extrafollicular accumulation of short-lived plasmablasts may contribute to this suboptimal immune response. In this review, we summarize some of those studies and attempt to connect certain host intrinsic features in response to the malarial disease and the resultant gaps in the immune response.

Protein-Centric Analysis of Personalized Antibody Repertoires Using LC-MS-Based Fab-Profiling on a timsTOF.

Endogenous antibodies, or immunoglobulins (Igs), abundantly present in body fluids, represent some of the most challenging samples to analyze, largely due to the immense variability in their sequences and concentrations. It has been estimated that our body can produce billions of different Ig proteins with different isotypes, making their individual analysis seemingly impossible. However, recent advances in protein-centric proteomics using LC-MS coupled to Orbitrap mass analyzers to profile intact Fab fragments formed by selective cleavage at the IgG-hinge revealed that IgG repertoires may be less diverse, albeit unique for each donor. Serum repertoires seem to be dominated by a few hundred clones that cumulatively make up 50-95% of the total IgG content. Enabling such analyses required careful optimization of the chromatography and mass analysis, as all Fab analytes are highly alike in mass (46-51 kDa) and sequence. To extend the opportunities of this mass-spectrometry-based profiling of antibody repertoires, we here report the optimization and evaluation of an alternative MS platform, namely, the timsTOF, for antibody repertoire profiling. The timsTOF mass analyzer has gained traction in recent years for peptide-centric proteomics and found wide applicability in plasma proteomics, affinity proteomics, and HLA peptidomics, to name a few. However, for protein-centric analysis, this platform has been less explored. Here, we demonstrate that the timsTOF platform can be adapted to perform protein-centric LC-MS-based profiling of antibody repertoires. In a side-by-side comparison of the timsTOF and the Orbitrap we demonstrate that the extracted serum antibody repertoires are alike qualitatively and quantitatively, whereby in particular the sensitivity of the timsTOF platform excels. Future incorporation of advanced top-down capabilities on the timsTOF may make this platform a very valuable alternative for protein-centric proteomics and top-down proteomics and thus also for personalized antibody repertoire profiling.

Humoral immune transcriptome signature in myelomeningocele patients.

INTRODUCTION: Myelomeningocele (MMC) results from incomplete closure of the neural tube, and has a complex multifactorial etiology, including an inflammatory microenvironment. OBJECTIVE: We evaluated the contribution of humoral immune response for development of inflammatory milieu. METHODS: Using public repository Gene Expression Omnibus (GEO), we retrieve dataset transcriptome from the amniotic fluid of ten fetuses with myelomeningocele and ten healthy control fetuses to found differential gene expression associated with disturbances and inflammatory signatures in MMC. The identified DEGs were submitted to enrichment, network, and matrix correlation analyses. RESULTS: Our initial analysis revealed 90 DEGs in MMC, mainly associated with signaling pathways of inflammation, including the immune modules, humoral immune response and IFN-type I signatures. Protein-protein analysis (PPI) revealed an association with three protein networks; positive regulation of B cell proliferation constituted the largest network. Matrix correlation analyses showed that MMC alters the co-expression of genes related to inflammatory processes that promote microenvironment inflammation. CONCLUSION: These results revealed an altered humoral immune response in MMC patients, contributing to an inflammatory profile and providing opportunities for identifying potential biomarkers in myelomeningocele disease.

Immunogenicity Parameters of Cancer Patients Receiving the mRNA Vaccine BNT162b2 While Obtaining Radiotherapy: A Longitudinal Cohort Evaluation.

BACKGROUND: Cancer patients are highly prone to infectious diseases. While undergoing antineoplastic treatment, the risk of severe symptoms upon infection increases, necessitating efficient protective measures, such as vaccination. For patients receiving radiotherapy, there is no specific information about humoral immunity. During the COVID-19 pandemic, serial antibody measurements were therefore offered to cancer patients, following SARS-CoV-2 vaccination while obtaining radiotherapy. METHODS: Out of 74 enrolled patients, 46 met the inclusion criteria. Two cohorts were allocated, depending on an association with chemotherapy or pure radiotherapy. An additional healthy control cohort of 16 healthcare workers was enrolled. All participants followed a two-fold BNT162b2 vaccine schedule. SARS-CoV-2 binding antibodies were measured serially in a 7-day cycle for 35 days and over the long-term, using the Elecsys® Anti-SARS-CoV-2 immunoassay. RESULTS: Cancer patients under pure radiotherapy have a comparable humoral vaccination response and long-term persistency of antibodies to healthy controls. Patients receiving additional chemotherapy show a significantly delayed immune response and decreased antibody titers. The vaccine was well tolerated in all cohorts. CONCLUSIONS: Pure radiotherapy in cancer patients does not interfere with the vaccine-induced humoral immune response or other immunogenetic aspects, whereas previous or simultaneous chemotherapy does. Findings are of particular relevance for future epidemic or pandemic scenarios.

Cell-Mediated Proteomics, and Serological and Mucosal Humoral Immune Responses after Seasonal Influenza Immunization: Characterization of Serological Responders and Non-Responders.

Immunization against influenza through vaccination is the most effective method with which to prevent infection. To assess protection after immunization, analysing humoral response with a hemagglutinin inhibition assay is the gold standard, but cell-mediated immune response has been shown to better correlate with protection in the elderly. Our aim was to explore the influenza-specific cell-mediated and mucosal humoral responses in serologically defined responders and non-responders. We analysed sera for total immunoglobulins (Ig) A, G, and M and nasal swab samples for influenza-specific IgA. Peripheral blood mononuclear cells were stimulated with trivalent influenza vaccine VaxiGripTetra, and supernatants were analysed for influenza-specific responses with the Olink Immune-Oncology panel using a proximity extension assay. We included 73 individuals, of which 69 completed the study with follow-up sampling at one and six months post-vaccination. Of the 73, 51 (70%) were found to be serological responders and 22 (30%) were non-responders. We did not find any significant differences in sex or mucosal humoral response between responders and non-responders; however, a higher IFNγ/IL-10 ratio in individuals ≤65 years of age indicates an enhanced cell-mediated immune response in this age group. Characteristics of the non-responders were found to be higher levels of IgM, Granzyme B and Interleukin 12, and lower levels of C-X-C motif chemokine 13 compared with those of the responders. In conclusion, our results did not show any correlation between serological response and age. Furthermore, the majority of influenza-specific cell-mediated immune markers did not differ between responders and non-responders; the immune marker profile of the non-responders and its contribution to protection is of interest but needs to be further explored.

B-cell intrinsic regulation of antibody mediated immunity by histone H2A deubiquitinase BAP1.

Introduction: BAP1 is a deubiquitinase (DUB) of the Ubiquitin C-terminal Hydrolase (UCH) family that regulates gene expression and other cellular processes, through its direct catalytic activity on the repressive epigenetic mark histone H2AK119ub, as well as on several other substrates. BAP1 is also a highly important tumor suppressor, expressed and functional across many cell types and tissues. In recent work, we demonstrated a cell intrinsic role of BAP1 in the B cell lineage development in murine bone marrow, however the role of BAP1 in the regulation of B cell mediated humoral immune response has not been previously explored. Methods and results: In the current study, we demonstrate that a B-cell intrinsic loss of BAP1 in activated B cells in the Bap1 fl/fl Cγ1-cre murine model results in a severe defect in antibody production, with altered dynamics of germinal centre B cell, memory B cell, and plasma cell numbers. At the cellular and molecular level, BAP1 was dispensable for B cell immunoglobulin class switching but resulted in an impaired proliferation of activated B cells, with genome-wide dysregulation in histone H2AK119ub levels and gene expression. Conclusion and discussion: In summary, our study establishes the B-cell intrinsic role of BAP1 in antibody mediated immune response and indicates its central role in the regulation of the genome-wide landscapes of histone H2AK119ub and downstream transcriptional programs of B cell activation and humoral immunity.

Evaluation of immunomodulatory (humoral as well as cell-mediated) and cytokines (TNF-α & IL-10) regulating potential of Neolamarckia cadamba fruit extract in Wistar albino rats.

Current work has been designed to investigate the immunomodulatory efficacy with particular reference to humoral, cell-mediated and cytokine-modulating potential of hot aqueous extract of Neolamarckia cadamba (HAENC) fruits in Wistar albino rats. The effect of different concentrations of HAENC fruits over cell-mediated immune response was assessed using six groups (Gp-I as control, Gp-II with 20 µg/mL, Gp-III with 50 µg/mL, Gp-IV with 100 µg/mL, Gp-V with 250 µg/mL, and Gp-VI with 500 µg/mL) of Wistar albino rats having six animals in each. The amount of tumor necrosis factor-α (TNF-α) and interleukin (IL)-10 was measured by sandwich ELISA with different concentrations of HAENC (50-500 µg/mL) in splenocyte culture supernatant and their expression was determined by qRT-PCR Humoral immune response was determined by measuring the serum antibody titer of Wistar albino rats against Salmonella typhimurium 'O' antigen using four groups containing six animals each (Gp-I as control, Gp II, III & IV were respectively fed orally with 125, 250, and 500 mg/Kg body weight using HAENC fruits). LC-MS analysis suggested the presence of cadambine, chlorogenic acid, cadambagenic acid, stearic acid, octadecanoic acid ethyl ether, and 7-hydroxy-5,2'-4'-trimethoxyflavonon in the extract based on their m/z ratio. The result suggested significant (p < 0.01) dose-dependent proliferation of Concanavalin A (Con A)-treated splenocytes, depicting cell-mediated immunostimulatory potential of HAENC fruits. A dose-dependent significant decrease (p < 0.01) was found in the amount of TNF-α and IL-10 was found to increase significantly (p < 0.01) as extract concentrations increased. TNF-α and IL-10 expressions were confirmed at the molecular level by qRT-PCR analysis of mRNA transcripts of TNF-α and IL-10 genes. Fold expression of TNF-α and IL-10 gene was 0.197 and 3.58 at 250 µg/mL, 0.02 and 20.11 at 500 µg/mL concentrations of HAENC respectively in comparison to control. Serum antibody titer was significantly increased (p < 0.01) in animals fed with different doses of HAENC fruits. The present study suggested the anti-inflammatory effect of HAENC fruits which also influences the networking of cytokines, implying that it may play a role in regulating the activity of the host's immune system and can serve as a potent herbal drug with immuno-stimulatory potential.

Highly heterogenous humoral immune response in Lyme disease patients revealed by broad machine learning-assisted antibody binding profiling with random peptide arrays.

Introduction: Lyme disease (LD), a rapidly growing public health problem in the US, represents a formidable challenge due to the lack of detailed understanding about how the human immune system responds to its pathogen, the Borrelia burgdorferi bacterium. Despite significant advances in gaining deeper insight into mechanisms the pathogen uses to evade immune response, substantial gaps remain. As a result, molecular tools for the disease diagnosis are lacking with the currently available tests showing poor performance. High interpersonal variability in immune response combined with the ability of the pathogen to use a number of immune evasive tactics have been implicated as underlying factors for the limited test performance. Methods: This study was designed to perform a broad profiling of the entire repertoire of circulating antibodies in human sera at the single-individual level using planar arrays of short linear peptides with random sequences. The peptides sample sparsely, but uniformly the entire combinatorial sequence space of the same length peptides for profiling the humoral immune response to a B.burg. infection and compare them with other diseases with etiology similar to LD and healthy controls. Results: The study revealed substantial variability in antibody binding profiles between individual LD patients even to the same antigen (VlsE protein) and strong similarity between individuals diagnosed with Lyme disease and healthy controls from the areas endemic to LD suggesting a high prevalence of seropositivity in endemic healthy control. Discussion: This work demonstrates the utility of the approach as a valuable analytical tool for agnostic profiling of humoral immune response to a pathogen.

Association of Nirmatrelvir/Ritonavir Treatment and COVID-19-Neutralizing Antibody Titers in a Longitudinal Health Care Worker Cohort.

Nirmatrelvir/ritonavir (NMV/r) is used for the treatment of coronavirus disease 2019 (COVID-19) infection. However, rebound COVID-19 infections can occur after taking NMV/r. We examined neutralizing antibodies to the severe acute respiratory syndrome coronavirus 2 spike protein before and after infection in people who did and did not take NMV/r to determine if NMV/r impedes the humoral immune response.

Transcriptomic Analysis Reveals Sixteen Potential Genes Associated with the Successful Differentiation of Antibody-Secreting Cells through the Utilization of Unfolded Protein Response Mechanisms in Robust Responders to the Influenza Vaccine.

The seasonal influenza vaccine remains one of the vital recommended infection control measures for the elderly with chronic illnesses. We investigated the immunogenicity of a single dose of influenza vaccine in 123 seronegative participants and classified them into four distinct groups, determined by the promptness of vaccine response, the longevity of humoral immunity, and the likelihood of exhibiting cross-reactivity. Subsequently, we used transcriptional profiling and differential gene expression analysis to identify potential genes directly associated with the robust response to the vaccine. The group of exemplary vaccine responders differentially expressed 16 genes, namely: MZB1, MYDGF, TXNDC5, TXNDC11, HSP90B1, FKBP11, PDIA5, PRDX4, CD38, SDC1, TNFRSF17, TNFRSF13B, PAX5, POU2AF1, IRF4, and XBP1. Our findings point out a list of expressed proteins that are related to B cell proliferation, unfolded protein response, and cellular haemostasis, as well as a linkage of these expressions to the survival of long-lived plasma cells.

High vaccination coverage and infection rate result in a robust SARS-CoV-2-specific immunity in the majority of liver cirrhosis and transplant patients: A single-center cross-sectional study.

BACKGROUND: In the third year of the SARS-CoV-2 pandemic, little is known about the vaccine- and infection-induced immune response in liver transplant recipients (LTR) and liver cirrhosis patients (LCP). OBJECTIVE: This cross-sectional study assessed the vaccination coverage, infection rate, and the resulting humoral and cellular SARS-CoV-2-specific immune responses in a cohort of LTR and LCP at the University Medical Center Hamburg-Eppendorf, Germany between March and May 2023. METHODS: Clinical and laboratory data from 244 consecutive patients (160 LTR and 84 LCP) were collected via chart review and a patient survey. Immune responses were determined via standard spike(S)- and nucleocapsid-protein serology and a spike-specific Interferon-gamma release assay (IGRA). RESULTS: On average, LTR and LCP were vaccinated 3.7 and 3.3 times, respectively and 59.4% of patients received ≥4 vaccinations. Altogether, 68.1% (109/160) of LTR and 70.2% (59/84) of LCP experienced a SARS-CoV-2 infection. Most infections occurred during the Omicron wave in 2022 after an average of 3.0 vaccinations. Overall, the hospitalization rate was low (<6%) in both groups. An average of 4.3 antigen contacts by vaccination and/or infection resulted in a seroconversion rate of 98.4%. However, 17.5% (28/160) of LTR and 8.3% (7/84) of LCP demonstrated only low anti-S titers (<1000 AU/ml), and 24.6% (16/65) of LTR and 20.4% (10/59) of LCP had negative or low IGRA responses. Patients with hybrid immunity (vaccination plus infection) elicited significantly higher anti-S titers compared with uninfected patients with the same number of spike antigen contacts. A total of 22.2% of patients refused additional booster vaccinations. CONCLUSION: By spring 2023, high vaccination coverage and infection rate have resulted in a robust, mostly hybrid, humoral and cellular immune response in most LTR and LCP. However, booster vaccinations with vaccines covering new variants seem advisable, especially in patients with low immune responses and risk factors for severe disease.

A Potential Association between Abdominal Obesity and the Efficacy of Humoral Immunity Induced by COVID-19 and by the AZD1222, Convidecia, BNT162b2, Sputnik V, and CoronaVac Vaccines.

Abdominal obesity is highly prevalent in Mexico and has a poor prognosis in terms of the severity of coronavirus disease (COVID-19) and low levels of antibodies induced by infection and vaccination. We evaluated the humoral immune response induced by COVID-19 and five different vaccination schedules in Mexican individuals with abdominal obesity and the effects of other variables. This prospective longitudinal cohort study included 2084 samples from 389 participants. The levels of anti-S1/S2 and anti-RBD IgG antibodies were measured at various time points after vaccination. A high prevalence of hospitalization and oxygen use was observed in individuals with abdominal obesity (AO) who had COVID-19 before vaccination; however, they also had high levels of anti-S1/S2 and anti-RBD-neutralizing IgG antibodies. The same was true for vaccination-induced antibody levels. However, their longevity was low. Interestingly, we did not observe significant differences in vaccine reactogenicity between abdominally obese and abdominally non-obese groups. Finally, individuals with a higher body mass index, older age, and previous COVID-19 had higher levels of antibodies induced by COVID-19 and vaccination. Therefore, it is important to evaluate other immunological and inflammatory factors to better understand the pathogenesis of COVID-19 in the presence of risk factors and to propose effective vaccination schedules for vulnerable populations.

Performance Analysis of Serodiagnostic Tests to Characterize the Incline and Decline of the Individual Humoral Immune Response in COVID-19 Patients: Impact on Diagnostic Management.

Serodiagnostic tests for antibody detection to estimate the immunoprotective status regarding SARS-CoV-2 support diagnostic management. This study aimed to investigate the performance of serological assays for COVID-19 and elaborate on test-specific characteristics. Sequential samples (n = 636) of four panels (acute COVID-19, convalescent COVID-19 (partly vaccinated post-infection), pre-pandemic, and cross-reactive) were tested for IgG by indirect immunofluorescence test (IIFT) and EUROIMMUN EUROLINE Anti-SARS-CoV-2 Profile (IgG). Neutralizing antibodies were determined by a virus neutralization test (VNT) and two surrogate neutralization tests (sVNT, GenScript cPass, and EUROIMMUN SARS-CoV-2 NeutraLISA). Analysis of the acute and convalescent panels revealed high positive (78.3% and 91.6%) and negative (91.6%) agreement between IIFT and Profile IgG. The sVNTs revealed differences in their positive (cPass: 89.4% and 97.0%, NeutraLISA: 71.5% and 72.1%) and negative agreement with VNT (cPass: 92.3% and 50.0%, NeutraLISA: 95.1% and 92.5%) at a diagnostic specificity of 100% for all tests. The cPass showed higher inhibition rates than NeutraLISA at VNT titers below 1:640. Cross-reactivities were only found by cPass (57.1%). Serodiagnostic tests, which showed substantial agreement and fast runtime, could provide alternatives for cell-based assays. The findings of this study suggest that careful interpretation of serodiagnostic results obtained at different times after SARS-CoV-2 antigen exposure is crucial to support decision-making in diagnostic management.

Evaluation the effect of dietary vitamin E, sesamin and thymoquinone bioactive compounds on immunological response, intestinal traits and MUC-2 gene expression in broiler Japanese quails (Coturnix japonica).

The current study was performed to determine the effect of dietary vitamin E, sesamin and thymoquinone bioactive lignans derived from sesame and black seed on immunological response, intestinal traits and Mucin2 gene expression in broiler quails. Three hundred and fifty (one days-old) quails were allotted to seven dietary treatments with five replicates as an experimental randomized design study. Treatments were basal diet as a control, control +100 and +200 mg of vitamin E, sesamin and thymoquinone per each kg of diet respectively. At 35 d of age, two quails from each pen were chosen, weighted, slaughtered, eviscerated and lymphoid organ relative weights were measured. Anti-body titers against Newcastle disease (ND), Sheep red blood cell (SRBC), and infectious bronchitis virus (IBV) and Avian influenza (AI) vaccination were determined. The serum activities of alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and serum antioxidant activates such as superoxide dismutase (SOD),glutathione peroxidase(GPX), catalase (CAT) and total antioxidant capacity (TAC) were examined. The cell mediated immunity by dinitrochlorobenzene (DNCB) and phytohemagglutinin (PHA) challenges were assessed. The microflora populations of ileum, morphological traits of jejunum and mucin2 gene expression were analyzed. Data showed that the lymphoid organ (thymus, spleen and Bursa) relative weights and antibody titer against HI, AI, SRBC and IB vaccination were increased compared to the control (p ≤ 0.05). Serum activities of ALP, ALT and AST were decreased under influences of dietary treatments (p ≤ 0.05). The serum antioxidant activates of GPX,SOD,CAT and TAC were increased and Increasing in mean skin thickness after DNCB challenge and decrease wing web swelling response to PHA mitojen injection were observed (p ≤ 0.05). Salmonella enterica, E-coli and Coliforms colonies were decrease and Lactobacillus colonies increased instead (p ≤ 0.05). The villus height and surface, crypt depth and goblet cells density were increased compared to the control (p ≤ 0.05). The expression of MUC2 gene increased under influnces of vitamin E, sesamin and thymoquinone supplemented diets (p ≤ 0.05).

Long-Term Analyses of SARS-CoV-2 Humoral and T Cell Responses and Breakthrough SARS-CoV-2 Infections after Two Doses of BNT162b2 Followed by mRNA-1273 and Bivalent Omicron-Adapted BNT162b2 Vaccines: A Prospective Study over 2 Years in Non-Immunocompromised Individuals.

Long-term analyses of the immune response following SARS-CoV-2 mRNA vaccines are essential to determining its characteristics and providing the basis for vaccination strategies. We conducted a prospective study in a cohort of 268 healthy adults followed for >2 years after two doses of BNT162b2. Antibodies targeting the receptor-binding domain of the S1 subunit of the spike of SARS-CoV-2 (anti-RBD) were measured at eight time points; T cell response was analyzed using an interferon-γ release assay. A total of 248 (93%) subjects received mRNA-1273 on month 9; 93 (35%) received the bivalent Omicron-adapted BNT162b2 vaccine between months 19 and 26. Breakthrough infections occurred in 215 (80%) participants, with frequencies unaffected by the additional vaccines. Anti-RBD declined over the initial 9 months, increased after mRNA-1273, and declined gradually thereafter. In 50 (17%) previously infected subjects, anti-RBD levels were significantly higher up to month 9 (p < 0.05) but subsequently declined below those of uninfected individuals. Anti-RBD titers protective against SARS-CoV-2 could not be defined. Most subjects developed a positive T cell response that remained after 26 months. Waning of protection against SARS-CoV-2 infection occurred over time, resulting in non-severe breakthrough infections in most participants. The evolution of anti-RBD suggests modulation of the immune response through immune imprinting.

Evaluation of Two Recombinant Protein-Based Vaccine Regimens against Campylobacter jejuni: Impact on Protection, Humoral Immune Responses and Gut Microbiota in Broilers.

Campylobacter infections in humans are traced mainly to poultry products. While vaccinating poultry against Campylobacter could reduce the incidence of human infections, no vaccine is yet available on the market. In our previous study using a plasmid DNA prime/recombinant protein boost vaccine regimen, vaccine candidate YP437 induced partial protective immune responses against Campylobacter in broilers. In order to optimise vaccine efficacy, the vaccination protocol was modified using a protein prime/protein boost regimen with a different number of boosters. Broilers were given two or four intramuscular protein vaccinations (with the YP437 vaccine antigen) before an oral challenge by C. jejuni during a 42-day trial. The caecal Campylobacter load, specific systemic and mucosal antibody levels and caecal microbiota in the vaccinated groups were compared with their respective placebo groups and a challenge group (Campylobacter infection only). Specific humoral immune responses were induced, but no reduction in Campylobacter caecal load was observed in any of the groups (p > 0.05). Microbiota beta diversity analysis revealed that the bacterial composition of the groups was significantly different (p ≤ 0.001), but that vaccination did not alter the relative abundance of the main bacterial taxa residing in the caeca. The candidate vaccine was ineffective in inducing a humoral immune response and therefore did not provide protection against Campylobacter spp. infection in broilers. More studies are required to find new candidates.

Diverging humoral and cellular immune responses due to Omicron-a national study from the Faroe Islands.

IMPORTANCE: The immunity following infection and vaccination with the SARS-CoV-2 Omicron variant is poorly understood. We investigated immunity assessed with antibody and T-cell responses under different scenarios in vaccinated and unvaccinated individuals with and without Omicron infection. We found that the humoral response was higher among vaccinated-naïve than unvaccinated convalescent. Unvaccinated with and without infection had comparable low humoral responses, whereas vaccinated with a second or third dose, independent of infection status, had increasingly higher levels. Only a minor fraction of unvaccinated individuals had detectable humoral responses following Omicron infection, while almost all had positive T-cell responses. In conclusion, primary Omicron infection mounts a low humoral immune response, enhanced by prior vaccination. Omicron infection induced a robust T-cell response in both unvaccinated and vaccinated, demonstrating that immune evasion of primary Omicron infection affects humoral immunity more than T-cell immunity.

SpiB regulates the expression of B-cell-related genes and increases the longevity of memory B cells.

Generation of memory B cells is one of the key features of adaptive immunity as they respond rapidly to re-exposure to the antigen and generate functional antibodies. Although the functions of memory B cells are becoming clearer, the regulation of memory B cell generation and maintenance is still not well understood. Here we found that transcription factor SpiB is expressed in some germinal center (GC) B cells and memory B cells and participates in the maintenance of memory B cells. Overexpression and knockdown analyses revealed that SpiB suppresses plasma cell differentiation by suppressing the expression of Blimp1 while inducing Bach2 in the in-vitro-induced germinal center B (iGB) cell culture system, and that SpiB facilitates in-vivo appearance of memory-like B cells derived from the iGB cells. Further analysis in IgG1+ cell-specific SpiB conditional knockout (cKO) mice showed that function of SpiB is critical for the generation of late memory B cells but not early memory B cells or GC B cells. Gene expression analysis suggested that SpiB-dependent suppression of plasma cell differentiation is independent of the expression of Bach2. We further revealed that SpiB upregulates anti-apoptosis and autophagy genes to control the survival of memory B cells. These findings indicate the function of SpiB in the generation of long-lasting memory B cells to maintain humoral memory.

Vaccine-induced SARS-CoV-2 antibody response: the comparability of S1-specific binding assays depends on epitope and isotype discrimination.

Background: Quantification of the SARS-CoV-2-specific immune response by serological immunoassays is critical for the management of the COVID-19 pandemic. In particular, neutralizing antibody titers to the viral spike (S) protein have been proposed as a correlate of protection (CoP). The WHO established the First International Standard (WHO IS) for anti-SARS-CoV-2 immunoglobulin (Ig) (NIBSC 20/136) to harmonize binding assays with the same antigen specificity by assigning the same unitage in binding antibody units (BAU)/ml. Method: In this study, we analyzed the S1-specific antibody response in a cohort of healthcare workers in Germany (n = 76) during a three-dose vaccination course over 8.5 months. Subjects received either heterologous or homologous prime-boost vaccination with ChAdOx1 nCoV-19 (AstraZeneca) and BNT162b2 (Pfizer-BioNTech) or three doses of BNT162b2. Antibodies were quantified using three anti-S1 binding assays (ELISA, ECLIA, and PETIA) harmonized to the WHO IS. Serum levels of neutralizing antibodies were determined using a surrogate virus neutralization test (sVNT). Binding assays were compared using Spearman's rank correlation and Passing-Bablok regression. Findings: All assays showed good correlation and similar antibody kinetics correlating with neutralizing potential. However, the assays show large proportional differences in BAU/ml. ECLIA and PETIA, which detect total antibodies against the receptor- binding domain (RBD) within the S1 subunit, interact similarly with the convalescent plasma-derived WHO IS but differently with vaccine serum, indicating a high sensitivity to the IgG/IgM/IgA ratio. Conclusion: All three binding assays allow monitoring of the antibody response in COVID-19-vaccinated individuals. However, the assay-specific differences hinder the definition of a common protective threshold in BAU/ml. Our results highlight the need for the thoughtful use of conversion factors and consideration of method-specific differences. To improve the management of future pandemics and harmonize total antibody assays, we should strive for reference material with a well-characterized Ig isotype composition.

Comparative immunogenicity and safety of Gam-COVID-Vac and Sinopharm BBIBP-CorV vaccines: results of a pilot clinical study.

Introduction: There are few comparative studies on efficiency of broad range COVID19 vaccination strategy. This pilot aims to describe the effect of mixed COVID19 vaccination on vaccination adoption and subsequent total immunity, Conducted in Republic of Belarus, this pilot clinical study shows varying immunogenic responses to Sputnik V (Gam-COVID-Vac), Russian Federation (RF) and Sinopharm (BBIBP-CorV), People's Republic of China (PRC) vaccines. Objective: To compare the immunogenicity and reactogenicity of Sputnik V (Gam-COVID-Vac) and Sinopharm (BBIBP-CorV) vaccines in vaccinated individuals.Materials and MethodsA total of 60 adults participated in the present study. The immune response after vaccination was assessed using enzyme immunoassay. IgG levels were measured in all participants at three time points: before vaccination, on the 42nd day after the first vaccine dose, and in 6 months after the first vaccine dose. Age, sex of participants, vaccine type, history of COVID-19/IgG seropositivity were included in the multivariate analysis. The results of the SARS-CoV-2 infection antibody test were quantified according to the WHO First International Standard (NIBSC code:20/136) and measured in international units (BAU/ml). Results: The study participants (n = 60) were divided into two groups where 50 % (n = 30) were vaccinated with Sputnik V (Gam-COVID-Vac), and 50 % (n = 30) were vaccinated with Sinopharm (BBIBP-CorV). Women represented 63 % and 77 % of Sputnik V and Sinopharm groups, respectively. The IgG levels on day 42 after the first vaccine dose were: Sputnik V (Gam-COVID-Vac): Me = 650.4 (642.2-669.4); Sinopharm (BBIBP-CorV: Me = 376.5 (290.9-526.4) (UMann-Whitney = 164, p = 0.000024). The IgG levels in 6 months after the first vaccine dose were: Sputnik V (Gam-COVID-Vac)Me = 608.7 (574.6-647.1); Sinopharm (BBIBP-CorV) Me = 106.3 (78.21-332.4); (UMann-Whitney = 172.5, p-value = 0.000042)). In a multivariate model Sputnik V vaccine type and IgG seropositivity at the baseline were significantly associated with higher levels of IgG both at 42 days and 6 months post-vaccination. Reactions after vaccination appeared in 27 vaccinated people (45 %). Conclusion: This pilot study demonstrated that Sputnik V (Gam-COVID-Vac) vaccine was more immunogenic than Sinopharm (BBIBP-CorV) vaccine. IgG levels in vaccinated individuals who previously recovered from SARS-CoV-2 infection (hybrid immunity) were higher than in SARS-CoV-2 infection immune-naive people. Reactions after vaccines administration were mild to moderate.