The durability of immune memory after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger RNA (mRNA) vaccination remains unclear. In this study, we longitudinally profiled vaccine ...responses in SARS-CoV-2–naïve and –recovered individuals for 6 months after vaccination. Antibodies declined from peak levels but remained detectable in most subjects at 6 months. By contrast, mRNA vaccines generated functional memory B cells that increased from 3 to 6 months postvaccination, with the majority of these cells cross-binding the Alpha, Beta, and Delta variants. mRNA vaccination further induced antigen-specific CD4
and CD8
T cells, and early CD4
T cell responses correlated with long-term humoral immunity. Recall responses to vaccination in individuals with preexisting immunity primarily increased antibody levels without substantially altering antibody decay rates. Together, these findings demonstrate robust cellular immune memory to SARS-CoV-2 and its variants for at least 6 months after mRNA vaccination.
We examined antibody and memory B cell responses longitudinally for ∼9–10 months after primary 2-dose SARS-CoV-2 mRNA vaccination and 3 months after a 3rd dose. Antibody decay stabilized between 6 ...and 9 months, and antibody quality continued to improve for at least 9 months after 2-dose vaccination. Spike- and RBD-specific memory B cells remained durable over time, and 40%–50% of RBD-specific memory B cells simultaneously bound the Alpha, Beta, Delta, and Omicron variants. Omicron-binding memory B cells were efficiently reactivated by a 3rd dose of wild-type vaccine and correlated with the corresponding increase in neutralizing antibody titers. In contrast, pre-3rd dose antibody titers inversely correlated with the fold-change of antibody boosting, suggesting that high levels of circulating antibodies may limit the added protection afforded by repeat short interval boosting. These data provide insight into the quantity and quality of mRNA-vaccine-induced immunity over time through 3 or more antigen exposures.
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•Neutralizing antibody titers stabilize ∼6 months after primary vaccination•Memory B cells are stable for >9 months postvaccination and >50% cross-bind Omicron•Omicron-reactive memory B cells are reactivated by a 3rd dose of wild-type vaccine•Low preboost antibody levels correlate with a greater fold increase after boosting
Immunization with 2 doses of mRNA vaccine encoding the ancestral SARS-CoV-2 spike protein induces a population of durable memory B cells with broad reactivity to viral variants including Omicron. Boosting with a 3rd dose of ancestral vaccine increases variant-neutralizing antibody levels, highlighting the significance of vaccine-induced B cell memory.
Patients with COVID-19 present with a wide variety of clinical manifestations. Thromboembolic events constitute a significant cause of morbidity and mortality in patients infected with SARS-CoV-2. ...Severe COVID-19 has been associated with hyperinflammation and pre-existing cardiovascular disease. Platelets are important mediators and sensors of inflammation and are directly affected by cardiovascular stressors. In this report, we found that platelets from severely ill, hospitalized COVID-19 patients exhibited higher basal levels of activation measured by P-selectin surface expression and had poor functional reserve upon
stimulation. To investigate this question in more detail, we developed an assay to assess the capacity of plasma from COVID-19 patients to activate platelets from healthy donors. Platelet activation was a common feature of plasma from COVID-19 patients and correlated with key measures of clinical outcome including kidney and liver injury, and APACHEIII scores. Further, we identified ferritin as a pivotal clinical marker associated with platelet hyperactivation. The COVID-19 plasma-mediated effect on control platelets was highest for patients that subsequently developed inpatient thrombotic events. Proteomic analysis of plasma from COVID-19 patients identified key mediators of inflammation and cardiovascular disease that positively correlated with
platelet activation. Mechanistically, blocking the signaling of the FcγRIIa-Syk and C5a-C5aR pathways on platelets, using antibody-mediated neutralization, IgG depletion or the Syk inhibitor fostamatinib, reversed this hyperactivity driven by COVID-19 plasma and prevented platelet aggregation in endothelial microfluidic chamber conditions. These data identified these potentially actionable pathways as central for platelet activation and/or vascular complications and clinical outcomes in COVID-19 patients. In conclusion, we reveal a key role of platelet-mediated immunothrombosis in COVID-19 and identify distinct, clinically relevant, targetable signaling pathways that mediate this effect.
Coronavirus disease 2019 (COVID-19) is currently a global pandemic, but human immune responses to the virus remain poorly understood. We used high-dimensional cytometry to analyze 125 COVID-19 ...patients and compare them with recovered and healthy individuals. Integrated analysis of ~200 immune and ~50 clinical features revealed activation of T cell and B cell subsets in a proportion of patients. A subgroup of patients had T cell activation characteristic of acute viral infection and plasmablast responses reaching >30% of circulating B cells. However, another subgroup had lymphocyte activation comparable with that in uninfected individuals. Stable versus dynamic immunological signatures were identified and linked to trajectories of disease severity change. Our analyses identified three immunotypes associated with poor clinical trajectories versus improving health. These immunotypes may have implications for the design of therapeutics and vaccines for COVID-19.
SARS-CoV-2 mRNA vaccines have shown remarkable clinical efficacy, but questions remain about the nature and kinetics of T cell priming. We performed longitudinal antigen-specific T cell analyses on ...healthy SARS-CoV-2-naive and recovered individuals prior to and following mRNA prime and boost vaccination. Vaccination induced rapid antigen-specific CD4+ T cell responses in naive subjects after the first dose, whereas CD8+ T cell responses developed gradually and were variable in magnitude. Vaccine-induced Th1 and Tfh cell responses following the first dose correlated with post-boost CD8+ T cells and neutralizing antibodies, respectively. Integrated analysis revealed coordinated immune responses with distinct trajectories in SARS-CoV-2-naive and recovered individuals. Last, whereas booster vaccination improved T cell responses in SARS-CoV-2-naive subjects, the second dose had little effect in SARS-CoV-2-recovered individuals. These findings highlight the role of rapidly primed CD4+ T cells in coordinating responses to the second vaccine dose in SARS-CoV-2-naive individuals.
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•mRNA vaccines generate antigen-specific T cells in a coordinated immune response•Vaccine-induced T cells resemble the durable memory cells primed by infection•Th1 and cTfh cell responses to the first dose correlate with second-dose responses•SARS-CoV-2-recovered individuals benefit from the first but not the second dose
SARS-CoV-2 mRNA vaccines have demonstrated remarkable efficacy, but T cell responses to vaccination have not been well studied. In a longitudinal cohort, Painter et al. show that mRNA vaccines activate SARS-CoV-2-specific T cells that could contribute to durable immunity. The findings highlight the central role of T cells in the two-dose vaccine regimen for individuals not previously infected with SARS-CoV-2.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly spread within the human population. Although SARS-CoV-2 is a novel coronavirus, most humans had been previously exposed to ...other antigenically distinct common seasonal human coronaviruses (hCoVs) before the coronavirus disease 2019 (COVID-19) pandemic. Here, we quantified levels of SARS-CoV-2-reactive antibodies and hCoV-reactive antibodies in serum samples collected from 431 humans before the COVID-19 pandemic. We then quantified pre-pandemic antibody levels in serum from a separate cohort of 251 individuals who became PCR-confirmed infected with SARS-CoV-2. Finally, we longitudinally measured hCoV and SARS-CoV-2 antibodies in the serum of hospitalized COVID-19 patients. Our studies indicate that most individuals possessed hCoV-reactive antibodies before the COVID-19 pandemic. We determined that ∼20% of these individuals possessed non-neutralizing antibodies that cross-reacted with SARS-CoV-2 spike and nucleocapsid proteins. These antibodies were not associated with protection against SARS-CoV-2 infections or hospitalizations, but they were boosted upon SARS-CoV-2 infection.
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•Some humans possessed cross-reactive SARS-CoV-2 antibodies prior to the pandemic•Pre-pandemic SARS-CoV-2 reactive antibodies are not associated with protection•Antibodies to a related betacoronavirus are boosted upon SARS-CoV-2 infection
Analysis of human serum samples before and after the onset of the COVID-19 pandemic show that antibodies against common seasonal human coronaviruses are cross-reactive against SARS-CoV-2 but do not confer cross-protection against infection or hospitalization.
Although critical illness has been associated with SARS-CoV-2-induced hyperinflammation, the immune correlates of severe COVID-19 remain unclear. Here, we comprehensively analyzed peripheral blood ...immune perturbations in 42 SARS-CoV-2 infected and recovered individuals. We identified extensive induction and activation of multiple immune lineages, including T cell activation, oligoclonal plasmablast expansion, and Fc and trafficking receptor modulation on innate lymphocytes and granulocytes, that distinguished severe COVID-19 cases from healthy donors or SARS-CoV-2-recovered or moderate severity patients. We found the neutrophil to lymphocyte ratio to be a prognostic biomarker of disease severity and organ failure. Our findings demonstrate broad innate and adaptive leukocyte perturbations that distinguish dysregulated host responses in severe SARS-CoV-2 infection and warrant therapeutic investigation.
Abstract
Most single cell analyses of human T cell heterogeneity use a single modality (i.e., RNA or ATAC or protein), with limited ability to deconvolute complex cellular and molecular alterations ...that can occur during human aging and disease. Here, we use a new trimodal single cell technology (TEA-seq) to elucidate the interplay between the surface proteome, transcriptome, and epigenome in more than 300,000 T cells from healthy children (11–13 yrs) and older adults (55–65 yrs). We uncover that age universally drives molecular reprogramming across all T cell subsets towards a more activated basal state. Naive CD4 T cells, considered relatively resistant to aging, exhibited far more pronounced transcriptional reprogramming than naive CD8 T cells, in which alterations are preferentially driven by compositional shifts in naive-like memory subsets. We further discover a novel naïve-like CD8aa T cell subset lost with age that displays an innate-like transcriptome, a KLF/SP-rich epigenome and high IL-21 receptor expression. These data reveal the complex molecular landscape of the human T cell compartment that may contribute to differential immune responses across age.
Supported by grants from NIH (K01 AG068373 to CEG) and the Allen Institute
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