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1.
Cell Rep ; 38(12): 110561, 2022 03 22.
Article in English | MEDLINE | ID: covidwho-1797095

ABSTRACT

Eliciting antibodies to surface-exposed viral glycoproteins can generate protective responses that control and prevent future infections. Targeting conserved sites may reduce the likelihood of viral escape and limit the spread of related viruses with pandemic potential. Here we leverage rational immunogen design to focus humoral responses on conserved epitopes. Using glycan engineering and epitope scaffolding in boosting immunogens, we focus murine serum antibody responses to conserved receptor binding motif (RBM) and receptor binding domain (RBD) epitopes following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike imprinting. Although all engineered immunogens elicit a robust SARS-CoV-2-neutralizing serum response, RBM-focusing immunogens exhibit increased potency against related sarbecoviruses, SARS-CoV, WIV1-CoV, RaTG13-CoV, and SHC014-CoV; structural characterization of representative antibodies defines a conserved epitope. RBM-focused sera confer protection against SARS-CoV-2 challenge. Thus, RBM focusing is a promising strategy to elicit breadth across emerging sarbecoviruses without compromising SARS-CoV-2 protection. These engineering strategies are adaptable to other viral glycoproteins for targeting conserved epitopes.


Subject(s)
COVID-19 , Viral Envelope Proteins , Animals , Mice , Mice, Inbred BALB C , SARS-CoV-2 , Spike Glycoprotein, Coronavirus
2.
Cell reports ; 2022.
Article in English | EuropePMC | ID: covidwho-1728215

ABSTRACT

Hauser et al. use structure-guided design to engineer SARS-2 immunogens that direct immune responses to conserved viral sites in context of preexisting immunity. In mice, these immunogens elicit antibodies that potently neutralize related coronaviruses, including those of potential pandemic concern. Structural characterization of selected antibodies explains this observation.

3.
Clin Infect Dis ; 74(6): 1081-1084, 2022 03 23.
Article in English | MEDLINE | ID: covidwho-1707490

ABSTRACT

The clinical significance of severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) RNA in stool remains uncertain. We found that extrapulmonary dissemination of infection to the gastrointestinal tract, assessed by the presence of SARS-CoV-2 RNA in stool, is associated with decreased coronavirus disease 2019 (COVID-19) survival. Measurement of SARS-CoV-2 RNA in stool may have utility for clinical risk assessment.


Subject(s)
COVID-19 , SARS-CoV-2 , Feces , Gastrointestinal Tract , Humans , RNA, Viral , SARS-CoV-2/genetics
4.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-312141

ABSTRACT

Effective countermeasures are needed against emerging coronaviruses of pandemic potential, similar to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Designing immunogens that elicit broadly neutralizing antibodies to conserved viral epitopes on the major surface glycoprotein, spike, such as the receptor binding domain (RBD) is one potential approach. Here, we report the generation of homotrimeric RBD immunogens from different sarbecoviruses using a stabilized, immune-silent trimerization tag. We find that a cocktail of these homotrimeric sarbecovirus RBDs elicit antibodies to conserved viral epitopes outside of the ACE-2 receptor binding motif. Importantly, these responses neutralize all sarbecovirus components even in context of prior SARS-CoV-2 imprinting. This may be an effective strategy for eliciting broadly neutralizing responses leading to a pan-sarbecovirus vaccine.Funding: We acknowledge funding from NIH R01s AI146779 (AGS), AI124378,AI137057 and AI153098 (DL), and a Massachusetts Consortium on Pathogenesis Readiness (MassCPR) grant (AGS);training grants: NIGMS T32 GM007753 (BMH and TMC);T32AI007245 (JF);F31 Al138368 (MS). A.B.B. is supported by the National Institutes for Drug Abuse (NIDA) Avenir New Innovator Award DP2DA040254, the MGH Transformative Scholars Program as well as funding from the Charles H. Hood Foundation. This independent research was supported by the Gilead Sciences Research Scholars Program in HIV.Conflict of Interest: Authors declare no competing interests.Ethical Approval: All experiments were conducted with institutional IACUC approval (MGH protocol 2014N000252).

5.
Sci Immunol ; 6(66): eabf1152, 2021 Dec 03.
Article in English | MEDLINE | ID: covidwho-1583226

ABSTRACT

Saponins are potent and safe vaccine adjuvants, but their mechanisms of action remain incompletely understood. Here, we explored the properties of several saponin formulations, including immune-stimulatory complexes (ISCOMs) formed by the self-assembly of saponin and phospholipids in the absence or presence of the Toll-like receptor 4 agonist monophosphoryl lipid A (MPLA). We found that MPLA self-assembles with saponins to form particles physically resembling ISCOMs, which we termed saponin/MPLA nanoparticles (SMNP). Saponin-containing adjuvants exhibited distinctive mechanisms of action, altering lymph flow in a mast cell­dependent manner and promoting antigen entry into draining lymph nodes. SMNP was particularly effective, exhibiting even greater potency than the compositionally related adjuvant AS01B in mice, and primed robust germinal center B cell, TFH, and HIV tier 2 neutralizing antibodies in nonhuman primates. Together, these findings shed new light on mechanisms by which saponin adjuvants act to promote the immune response and suggest that SMNP may be a promising adjuvant in the setting of HIV, SARS-CoV-2, and other pathogens.


Subject(s)
Adaptive Immunity/drug effects , Adjuvants, Immunologic/pharmacology , Lymph/drug effects , Saponins/pharmacology , Toll-Like Receptors/agonists , Animals , B-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/immunology , Female , Lymph/physiology , Macaca mulatta , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Nanoparticles , Rats , Rats, Wistar
6.
PubMed; 2020.
Preprint in English | PubMed | ID: ppcovidwho-292772

ABSTRACT

Humoral responses in COVID-19 disease are often of limited durability, as seen with other human coronavirus epidemics. To address the underlying etiology, we examined postmortem thoracic lymph nodes and spleens in acute SARS-CoV-2 infection and observed the absence of germinal centers, a striking reduction in Bcl-6+ germinal center B cells but preservation of AID+ B cells. Absence of germinal centers correlated with an early specific block in Bcl-6+TFH cell differentiation together with an increase in T-bet+TH1 cells and aberrant extra-follicular TNF-a accumulation. Parallel peripheral blood studies revealed loss of transitional and follicular B cells in severe disease and accumulation of SARS-CoV-2-specific "disease-related" B cell populations. These data identify defective Bcl-6+TFH cell generation and dysregulated humoral immune induction early in COVID-19 disease, providing a mechanistic explanation for the limited durability of antibody responses in coronavirus infections and suggest that achieving herd immunity through natural infection may be difficult. Funding: This work was supported by NIH U19 AI110495 to SP, NIH R01 AI146779 to AGS, NIH R01AI137057 and DP2DA042422 to DL, BMH was supported by NIGMS T32 GM007753, TMC was supported by T32 AI007245. Funding for these studies from the Massachusetts Consortium of Pathogen Readiness, the Mark and Lisa Schwartz Foundation and Enid Schwartz is also acknowledged. Conflict of Interest: None. Ethical Approval: This study was performed with the approval of the Institutional Review Boards at the Massachusetts General Hospital and the Brigham and Women's Hospital.

7.
SSRN; 2021.
Preprint in English | SSRN | ID: ppcovidwho-291966

ABSTRACT

Eliciting antibodies to surface-exposed viral glycoproteins can generate protective responses that control and prevent future infections. Targeting conserved sites may reduce the likelihood of viral escape and limit spread of related viruses with pandemic potential. Here, we leveraged rational immunogen design to focus humoral responses on conserved epitopes. Using glycan engineering and epitope scaffolding, we directed murine serum antibody responses to conserved receptor binding motif (RBM) and domain (RBD) epitopes in the context of SARS-CoV-2 spike imprinting. Whereas all engineered immunogens elicited a robust SARS-CoV-2-neutralizing serum response, the RBM-focusing immunogens exhibited increased potency against related sarbecoviruses, SARS-CoV, WIV1-CoV, RaTG13-CoV, and SHC014-CoV;structural characterization of representative antibodies defined a conserved epitope. Furthermore, the RBM-focused sera conferred protection against SARS-CoV-2 challenge. Thus, RBM focusing is a promising strategy to elicit breadth across emerging sarbecoviruses without compromising SARS-CoV-2 protection. Broadly, these engineering strategies are adaptable to other viral glycoproteins for targeting conserved epitopes.

8.
Sci Immunol ; 6(66): eabl5842, 2021 Dec 10.
Article in English | MEDLINE | ID: covidwho-1467664

ABSTRACT

Initial exposure to a pathogen elicits an adaptive immune response to control and eradicate the threat. Interrogating the abundance and specificity of the naive B cell repertoire drives understanding of how to mount protective responses. Here, we isolated naive B cells from eight seronegative human donors targeting the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor binding domain (RBD). Single-cell B cell receptor (BCR) sequencing identified diverse gene usage and no restriction on complementarity determining region length. A subset of recombinant antibodies produced by naive B cell precursors bound to SARS-CoV-2 RBD and engaged circulating variants including B.1.1.7, B.1.351, and B.1.617.2, as well as preemergent bat-derived coronaviruses RaTG13, SHC104, and WIV1. By structural characterization of a naive antibody in complex with SARS-CoV-2 spike, we identified a conserved mode of recognition shared with infection-induced antibodies. We found that representative naive antibodies could signal in a B cell activation assay, and by using directed evolution, we could select for a higher-affinity RBD interaction, conferred by a single amino acid change. The minimally mutated, affinity-matured antibodies also potently neutralized SARS-CoV-2. Understanding the SARS-CoV-2 RBD­specific naive repertoire may inform potential responses capable of recognizing future SARS-CoV-2 variants or emerging coronaviruses, enabling the development of pan-coronavirus vaccines aimed at engaging protective germline responses.


Subject(s)
B-Lymphocytes/cytology , B-Lymphocytes/immunology , Coronavirus/immunology , SARS-CoV-2/immunology , Antibodies, Neutralizing/immunology , Antigens, Viral/immunology , B-Lymphocytes/metabolism , COVID-19/immunology , COVID-19 Vaccines/immunology , Epitopes , Humans , Lymphocyte Activation , SARS-CoV-2/classification , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/metabolism
9.
Clin Infect Dis ; 74(6): 1081-1084, 2022 03 23.
Article in English | MEDLINE | ID: covidwho-1303899

ABSTRACT

The clinical significance of severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) RNA in stool remains uncertain. We found that extrapulmonary dissemination of infection to the gastrointestinal tract, assessed by the presence of SARS-CoV-2 RNA in stool, is associated with decreased coronavirus disease 2019 (COVID-19) survival. Measurement of SARS-CoV-2 RNA in stool may have utility for clinical risk assessment.


Subject(s)
COVID-19 , SARS-CoV-2 , Feces , Gastrointestinal Tract , Humans , RNA, Viral , SARS-CoV-2/genetics
11.
Cell ; 184(2): 476-488.e11, 2021 01 21.
Article in English | MEDLINE | ID: covidwho-1012326

ABSTRACT

Coronavirus disease 2019 (COVID-19) exhibits variable symptom severity ranging from asymptomatic to life-threatening, yet the relationship between severity and the humoral immune response is poorly understood. We examined antibody responses in 113 COVID-19 patients and found that severe cases resulting in intubation or death exhibited increased inflammatory markers, lymphopenia, pro-inflammatory cytokines, and high anti-receptor binding domain (RBD) antibody levels. Although anti-RBD immunoglobulin G (IgG) levels generally correlated with neutralization titer, quantitation of neutralization potency revealed that high potency was a predictor of survival. In addition to neutralization of wild-type SARS-CoV-2, patient sera were also able to neutralize the recently emerged SARS-CoV-2 mutant D614G, suggesting cross-protection from reinfection by either strain. However, SARS-CoV-2 sera generally lacked cross-neutralization to a highly homologous pre-emergent bat coronavirus, WIV1-CoV, which has not yet crossed the species barrier. These results highlight the importance of neutralizing humoral immunity on disease progression and the need to develop broadly protective interventions to prevent future coronavirus pandemics.


Subject(s)
Antibodies, Neutralizing/immunology , Biomarkers/analysis , COVID-19/immunology , COVID-19/physiopathology , Adult , Antibodies, Neutralizing/analysis , Antibodies, Viral/analysis , Antibodies, Viral/blood , Biomarkers/blood , COVID-19/blood , COVID-19/epidemiology , Comorbidity , Coronavirus/classification , Coronavirus/physiology , Cross Reactions , Cytokines/blood , Enzyme-Linked Immunosorbent Assay , Female , Humans , Immunoglobulin A/analysis , Immunoglobulin G/blood , Immunoglobulin G/immunology , Immunoglobulin M/blood , Immunoglobulin M/immunology , Male , Massachusetts/epidemiology , Middle Aged , Protein Domains , SARS-CoV-2/chemistry , SARS-CoV-2/physiology , Severity of Illness Index , Spike Glycoprotein, Coronavirus/chemistry , Survival Analysis , Treatment Outcome
12.
Immunity ; 54(2): 235-246.e5, 2021 02 09.
Article in English | MEDLINE | ID: covidwho-988081

ABSTRACT

The interleukin-6 (IL-6) membrane receptor and its circulating soluble form, sIL-6R, can be targeted by antibody therapy to reduce deleterious immune signaling caused by chronic overexpression of the pro-inflammatory cytokine IL-6. This strategy may also hold promise for treating acute hyperinflammation, such as observed in coronavirus disease 2019 (COVID-19), highlighting a need to define regulators of IL-6 homeostasis. We found that conventional dendritic cells (cDCs), defined in mice via expression of the transcription factor Zbtb46, were a major source of circulating sIL-6R and, thus, systemically regulated IL-6 signaling. This was uncovered through identification of a cDC-dependent but T cell-independent modality that naturally adjuvants plasma cell differentiation and antibody responses to protein antigens. This pathway was then revealed as part of a broader biological buffer system in which cDC-derived sIL-6R set the in-solution persistence of IL-6. This control axis may further inform the development of therapeutic agents to modulate pro-inflammatory immune reactions.


Subject(s)
Dendritic Cells/immunology , Interleukin-6/blood , Interleukin-6/immunology , ADAM17 Protein , Animals , Cell Differentiation , Immunity, Humoral , Immunoglobulin M/immunology , Inflammation , Interferon Regulatory Factors/genetics , Interferon Regulatory Factors/immunology , Interleukin-6/genetics , Membrane Glycoproteins/immunology , Mice , Mice, Inbred C57BL , Mice, Transgenic , Plasma Cells/immunology , Receptors, Interleukin-6/blood , Receptors, Interleukin-6/immunology , Signal Transduction/immunology , Toll-Like Receptor 4/immunology , Toll-Like Receptor 7/immunology
15.
Cell ; 183(1): 143-157.e13, 2020 10 01.
Article in English | MEDLINE | ID: covidwho-720447

ABSTRACT

Humoral responses in coronavirus disease 2019 (COVID-19) are often of limited durability, as seen with other human coronavirus epidemics. To address the underlying etiology, we examined post mortem thoracic lymph nodes and spleens in acute SARS-CoV-2 infection and observed the absence of germinal centers and a striking reduction in Bcl-6+ germinal center B cells but preservation of AID+ B cells. Absence of germinal centers correlated with an early specific block in Bcl-6+ TFH cell differentiation together with an increase in T-bet+ TH1 cells and aberrant extra-follicular TNF-α accumulation. Parallel peripheral blood studies revealed loss of transitional and follicular B cells in severe disease and accumulation of SARS-CoV-2-specific "disease-related" B cell populations. These data identify defective Bcl-6+ TFH cell generation and dysregulated humoral immune induction early in COVID-19 disease, providing a mechanistic explanation for the limited durability of antibody responses in coronavirus infections, and suggest that achieving herd immunity through natural infection may be difficult.


Subject(s)
Coronavirus Infections/immunology , Germinal Center/immunology , Pneumonia, Viral/immunology , T-Lymphocytes, Helper-Inducer/immunology , Aged , Aged, 80 and over , B-Lymphocytes/immunology , COVID-19 , Female , Germinal Center/pathology , Humans , Male , Middle Aged , Pandemics , Proto-Oncogene Proteins c-bcl-6/genetics , Proto-Oncogene Proteins c-bcl-6/metabolism , Spleen/immunology , Spleen/pathology , Tumor Necrosis Factor-alpha/metabolism
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