The spike-specific TCRß repertoire shows distinct features in unvaccinated or vaccinated patients with SARS-CoV-2 infection.

BACKGROUND: The evolving variants of SARS-CoV-2 may escape immunity from prior infections or vaccinations. It's vital to understand how immunity adapts to these changes. Both infection and mRNA vaccination induce T cells that target the Spike protein. These T cells can recognize multiple variants, such as Delta and Omicron, even if neutralizing antibodies are weakened. However, the degree of recognition can vary among people, affecting vaccine efficacy. Previous studies demonstrated the capability of T-cell receptor (TCR) repertoire analysis to identify conserved and immunodominant peptides with cross-reactive potential among variant of concerns. However, there is a need to extend the analysis of the TCR repertoire to different clinical scenarios. The aim of this study was to examine the Spike-specific TCR repertoire profiles in natural infections and those with combined natural and vaccine immunity. METHODS: A T-cell enrichment approach and bioinformatic tools were used to investigate the Spike-specific TCRß repertoire in peripheral blood mononuclear cells of previously vaccinated (n = 8) or unvaccinated (n = 6) COVID-19 patients. RESULTS: Diversity and clonality of the TCRß repertoire showed no significant differences between vaccinated and unvaccinated groups. When comparing the TCRß data to public databases, 692 unique TCRß sequences linked to S epitopes were found in the vaccinated group and 670 in the unvaccinated group. TCRß clonotypes related to spike regions S135-177, S264-276, S319-350, and S448-472 appear notably more prevalent in the vaccinated group. In contrast, the S673-699 epitope, believed to have super antigenic properties, is observed more frequently in the unvaccinated group. In-silico analyses suggest that mutations in epitopes, relative to the main SARS-CoV-2 variants of concern, don't hinder their cross-reactive recognition by associated TCRß clonotypes. CONCLUSIONS: Our findings reveal distinct TCRß signatures in vaccinated and unvaccinated individuals with COVID-19. These differences might be associated with disease severity and could influence clinical outcomes. TRIAL REGISTRATION: FESR/FSE 2014-2020 DDRC n. 585, Action 10.5.12, noCOVID19@UMG.

T-cell immunity against Severe Acute Respiratory Syndrome Coronavirus 2 proteins in patients with type 1 diabetes.

AIMS: Individuals with type 1 diabetes (T1D) do not appear to have an elevated risk of severe Coronavirus Disease 19 (COVID-19). Pre-existing immune reactivity to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in unexposed individuals may serve as a protective factor. Hence, our study was designed to evaluate the existence of T cells with reactivity against SARS-CoV-2 antigens in unexposed patients with T1D. MATERIALS AND METHODS: Peripheral blood mononuclear cells (PBMCs) were collected from SARS-CoV-2 unexposed patients with T1D and healthy control subjects. SARS-CoV-2 specific T cells were identified in PBMCs by ex-vivo interferon (IFN)γ-ELISpot and flow cytometric assays. The epitope specificity of T cells in T1D was inferred through T Cell Receptor sequencing and GLIPH2 clustering analysis. RESULTS: T1D patients unexposed to SARS-CoV-2 exhibited higher rates of virus-specific T cells than controls. The T cells primarily responded to peptides from the ORF7/8, ORF3a, and nucleocapsid proteins. Nucleocapsid peptides predominantly indicated a CD4+ response, whereas ORF3a and ORF7/8 peptides elicited both CD4+ and CD8+ responses. The GLIPH2 clustering analysis of TCRß sequences suggested that TCRß clusters, associated with the autoantigens proinsulin and Zinc transporter 8 (ZnT-8), might share specificity towards ORF7b and ORF3a viral epitopes. Notably, PBMCs from three T1D patients exhibited T cell reactivity against both ORF7b/ORF3a viral epitopes and proinsulin/ZnT-8 autoantigens. CONCLUSIONS: The increased frequency of SAR-CoV-2- reactive T cells in T1D patients might protect against severe COVID-19 and overt infections. These results emphasise the long-standing association between viral infections and T1D.

Humoral and T-cell response to SARS-CoV-2 mRNA vaccine in multiple sclerosis patients: Correlations with DMTs and clinical variables.

Disease-modifying therapies (DMTs) can affect vaccine responses in individuals with multiple sclerosis (MS). We assessed the humoral and T-cell responses following SARS-CoV-2 mRNA vaccination in MS patients receiving various DMTs. We prospectively enrolled 243 participants, including 113 healthy control subjects and 130 MS patients. Blood samples for detecting SARS-CoV-2 antibodies were collected at three time points: T0, before the first vaccine dose; T1, before the second dose; and T2, one month after the second dose. In a subgroup of 51 patients and 20 controls, samples were collected at T0 and T2 to assess the T-cell immune response to the Spike antigen of SARS-CoV-2 using ELISPOT-IFNγ. The IgG levels in patients treated with fingolimod and ocrelizumab (159.1 AU/ml and 467.1 AU/ml, respectively) were significantly lower than those in healthy controls and patients on other DMTs (P â€‹< â€‹0.0001). The mean Ig titers were higher in patients with an absolute lymphocyte count ≥1000 â€‹cells/mm3 compared to those with a count between 500 and 1000 and with a count <500 (mean â€‹± â€‹SD:7205.6 â€‹± â€‹7339.2, 2413.1 â€‹± â€‹4515.4 and 165.9 â€‹± â€‹152.2, respectively; p â€‹= â€‹0.008). We found correlations between antibody levels and age (r â€‹= â€‹0.233, p â€‹= â€‹0.008). A positive Spike-specific T-cell response was detectable in 100 â€‹% of vaccinated healthy controls and patients treated with teriflunomide, dimethyl-fumarate, and natalizumab, in 90.5 â€‹% of fingolimod patients, and in 63.8 â€‹% of ocrelizumab patients. There is a correlation between IgG-specific titer after SARS-CoV-2 vaccination and clinical variables (age, lymphocyte count). Notably, a T-cell-specific response to SARS-CoV-2 developed in patients treated with fingolimod and ocrelizumab, even with lower rates of humoral response.

The biological variation of serum 1,25-dihydroxyvitamin D and parathyroid hormone, and plasma fibroblast growth factor 23 in healthy individuals.

BACKGROUND AND AIMS: Measuring 1,25-dihydroxyvitamin D (1,25(OH)2D), parathyroid hormone 1-84 (PTH 1-84) and intact FGF23 (iFGF23) is crucial for diagnosing a variety of diseases affecting bone and mineral homeostasis. Biological variability (BV) data are important for defining analytical quality specifications (APS), the usefulness of reference intervals, and the significance of variations in serial measurements in the same subject. The aim of this study was to pioneer the provision of BV estimates for 1,25(OH)2D and to improve existing BV estimates for iFGF23 and PTH 1-84. MATERIALS AND METHODS: Serum and plasma-EDTA samples of sixteen healthy subjects have been collected for seven weeks and measured in duplicate by chemiluminescent immunoassay on the DiaSorin Liaison platform. After variance verification, within-subject (CVI) and between-subject (CVG) BV estimates were assessed by either standard ANOVA, or CV-ANOVA. The APSs were calculated according to the EFLM-BV-model. RESULTS: We found the following CVI estimates with 95% confidence intervals:1,25(OH)2D, 22.2% (18.9-26.4); iFGF23, 16.1% (13.5-19.5); and PTH 1-84, 17.9% (14.8-21.8). The CVG were: 1,25(OH)2D, 21.2% (14.2-35.1); iFGF23, 21.1% (14.5-35.8); and PTH 1-84, 31.1% (22.1-50.8). CONCLUSIONS: We report for the first time BV estimates for 1,25(OH)2D and enhance existing data about iFGF23-BV and PTH 1-84-BV through cutting-edge immunometric methods.

Spike-specific T-cell responses in patients with COVID-19 successfully treated with neutralizing monoclonal antibodies against SARS-CoV-2.

OBJECTIVES: Neutralizing monoclonal antibodies (moAbs) improves clinical outcomes in patients with COVID-19 when administered during the initial days of infection. The action of moAbs may impair the generation or maintenance of effective immune memory, similar to that demonstrated in other viral diseases. We aimed to evaluate short-term memory T-cell responses in patients effectively treated with bamlanivimab/etesevimab, casirivimab/imdevimab, or sotrovimab (SOT). METHODS: Spike (S)-specific T-cell responses were analyzed in 23 patients with COVID-19 (vaccinated or unvaccinated) before and after a median of 50 (range: 28-93) days from moAb treatment, compared with 11 vaccinated healthy controls. T-cell responses were measured by interferon-γ-enzyme-linked immunospot and flow cytometric activation-induced marker assay. RESULTS: No statistically significant difference in S-specific T-cell responses was observed between patients treated with moAb and vaccinated healthy controls. Bamlanivimab/etesevimab and casirivimab/imdevimab groups showed significant increases in cellular responses in paired baseline/postrecovery series, as well as vaccinated patients receiving SOT. In contrast, unvaccinated patients prescribed SOT presented no statistically significant increases in T-cell-responses, suggesting diverse impacts of different moAbs on the evolution of S-specific T-cell responses in vaccinated and unvaccinated patients. CONCLUSION: The moAbs did not hinder short-term memory S-specific T-cell responses in the overall group of patients; however, differences among moAbs must be further investigated both in vaccinated and unvaccinated individuals.