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1.
Clin Infect Dis ; 73(11): 2000-2008, 2021 12 06.
Article in English | MEDLINE | ID: covidwho-1559548

ABSTRACT

BACKGROUND: Vaccine-induced neutralizing antibodies are key in combating the coronavirus disease 2019 (COVID-19) pandemic. However, delays of boost immunization due to limited availability of vaccines may leave individuals vulnerable to infection and prolonged or severe disease courses. The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOC)-B.1.1.7 (United Kingdom), B.1.351 (South Africa), and P.1 (Brazil)-may exacerbate this issue, as the latter two are able to evade control by antibodies. METHODS: We assessed humoral and T-cell responses against SARS-CoV-2 wild-type (WT), VOC, and endemic human coronaviruses (hCoVs) that were induced after single and double vaccination with BNT162b2. RESULTS: Despite readily detectable immunoglobulin G (IgG) against the receptor-binding domain of the SARS-CoV-2 S protein at day 14 after a single vaccination, inhibition of SARS-CoV-2 S-driven host cell entry was weak and particularly low for the B.1.351 variant. Frequencies of SARS-CoV-2 WT and VOC-specific T cells were low in many vaccinees after application of a single dose and influenced by immunity against endemic hCoV. The second vaccination significantly boosted T-cell frequencies reactive for WT and B.1.1.7 and B.1.351 variants. CONCLUSIONS: These results call into question whether neutralizing antibodies significantly contribute to protection against COVID-19 upon single vaccination and suggest that cellular immunity is central for the early defenses against COVID-19.


Subject(s)
/immunology , COVID-19 , Immunity, Cellular , Immunity, Humoral , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , COVID-19/immunology , COVID-19/prevention & control , Humans , Immunoglobulin G/blood , Spike Glycoprotein, Coronavirus/immunology , T-Lymphocytes/immunology , Vaccination
2.
J Clin Microbiol ; 59(7): e0051421, 2021 06 18.
Article in English | MEDLINE | ID: covidwho-1486483

ABSTRACT

Accurate SARS-CoV-2 serological assays are critical for COVID-19 serosurveillance. However, previous studies have indicated possible cross-reactivity of these assays, including in areas where malaria is endemic. We tested 213 well-characterized prepandemic samples from Nigeria using two SARS-CoV-2 serological assays, Abbott Architect IgG and Euroimmun NCP IgG assay, both targeting SARS-CoV-2 nucleocapsid protein. To assess antibody binding strength, an avidity assay was performed on these samples and on plasma from SARS-CoV-2 PCR-positive persons. Thirteen (6.1%) of 212 samples run on the Abbott assay and 38 (17.8%) of 213 run on the Euroimmun assay were positive. Anti-Plasmodium IgG levels were significantly higher among false positives for both Abbott and Euroimmun; no association was found with active Plasmodium falciparum infection. An avidity assay using various concentrations of urea wash in the Euroimmun assay reduced loosely bound IgG: of 37 positive/borderline prepandemic samples, 46%, 86%, 89%, and 97% became negative using 2 M, 4 M, 5 M, and 8 M urea washes, respectively. The wash slightly reduced avidity of antibodies from SARS-CoV-2 patients within 28 days of PCR confirmation; thereafter, avidity increased for all urea concentrations except 8 M. This validation found moderate to substantial cross-reactivity on two SARS-CoV-2 serological assays using samples from a setting where malaria is endemic. A simple urea wash appeared to alleviate issues of cross-reactivity.


Subject(s)
COVID-19 , Malaria , Antibodies, Viral , Humans , Malaria/diagnosis , Nigeria , SARS-CoV-2 , Sensitivity and Specificity
3.
Res Sq ; 2021 Feb 15.
Article in English | MEDLINE | ID: covidwho-1417405

ABSTRACT

Recently approved vaccines have already shown remarkable protection in limiting SARS-CoV-2 associated disease. However, immunologic mechanism(s) of protection, as well as how boosting alters immunity to wildtype and newly emerging strains, remain incompletely understood. Here we deeply profiled the humoral immune response in a cohort of non-human primates immunized with a stable recombinant full-length SARS-CoV-2 spike (S) glycoprotein (NVX-CoV2373) at two dose levels, administered as a single or two-dose regimen with a saponin-based adjuvant Matrix-M™. While antigen dose had some effect on Fc-effector profiles, both antigen dose and boosting significantly altered overall titers, neutralization and Fc-effector profiles, driving unique vaccine-induced antibody fingerprints. Combined differences in antibody effector functions and neutralization were strongly associated with distinct levels of protection in the upper and lower respiratory tract, pointing to the presence of combined, but distinct, compartment-specific neutralization and Fc-mechanisms as key determinants of protective immunity against infection. Moreover, NVX-CoV2373 elicited antibodies functionally target emerging SARS-CoV-2 variants, collectively pointing to the critical collaborative role for Fab and Fc in driving maximal protection against SARS-CoV-2. Collectively, the data presented here suggest that a single dose may prevent disease, but that two doses may be essential to block further transmission of SARS-CoV-2 and emerging variants.

5.
NPJ Vaccines ; 6(1): 50, 2021 Apr 09.
Article in English | MEDLINE | ID: covidwho-1387358

ABSTRACT

The development of an effective AIDS vaccine remains a challenge. Nucleoside-modified mRNAs formulated in lipid nanoparticles (mRNA-LNP) have proved to be a potent mode of immunization against infectious diseases in preclinical studies, and are being tested for SARS-CoV-2 in humans. A critical question is how mRNA-LNP vaccine immunogenicity compares to that of traditional adjuvanted protein vaccines in primates. Here, we show that mRNA-LNP immunization compared to protein immunization elicits either the same or superior magnitude and breadth of HIV-1 Env-specific polyfunctional antibodies. Immunization with mRNA-LNP encoding Zika premembrane and envelope or HIV-1 Env gp160 induces durable neutralizing antibodies for at least 41 weeks. Doses of mRNA-LNP as low as 5 µg are immunogenic in macaques. Thus, mRNA-LNP can be used to rapidly generate single or multi-component vaccines, such as sequential vaccines needed to protect against HIV-1 infection. Such vaccines would be as or more immunogenic than adjuvanted recombinant protein vaccines in primates.

6.
Sci Immunol ; 6(58)2021 04 15.
Article in English | MEDLINE | ID: covidwho-1349998

ABSTRACT

Novel mRNA vaccines for SARS-CoV-2 have been authorized for emergency use. Despite their efficacy in clinical trials, data on mRNA vaccine-induced immune responses are mostly limited to serological analyses. Here, we interrogated antibody and antigen-specific memory B cells over time in 33 SARS-CoV-2 naïve and 11 SARS-CoV-2 recovered subjects. SARS-CoV-2 naïve individuals required both vaccine doses for optimal increases in antibodies, particularly for neutralizing titers against the B.1.351 variant. Memory B cells specific for full-length spike protein and the spike receptor binding domain (RBD) were also efficiently primed by mRNA vaccination and detectable in all SARS-CoV-2 naive subjects after the second vaccine dose, though the memory B cell response declined slightly with age. In SARS-CoV-2 recovered individuals, antibody and memory B cell responses were significantly boosted after the first vaccine dose; however, there was no increase in circulating antibodies, neutralizing titers, or antigen-specific memory B cells after the second dose. This robust boosting after the first vaccine dose strongly correlated with levels of pre-existing memory B cells in recovered individuals, identifying a key role for memory B cells in mounting recall responses to SARS-CoV-2 antigens. Together, our data demonstrated robust serological and cellular priming by mRNA vaccines and revealed distinct responses based on prior SARS-CoV-2 exposure, whereby COVID-19 recovered subjects may only require a single vaccine dose to achieve peak antibody and memory B cell responses. These findings also highlight the utility of defining cellular responses in addition to serologies and may inform SARS-CoV-2 vaccine distribution in a resource-limited setting.


Subject(s)
Antibodies, Viral/immunology , B-Lymphocytes/immunology , COVID-19 Vaccines , COVID-19/immunology , SARS-CoV-2/immunology , Vaccines, Synthetic , Adult , Antibodies, Neutralizing/immunology , Antibodies, Viral/blood , Female , Humans , Male , Middle Aged , RNA, Messenger , Spike Glycoprotein, Coronavirus/immunology , Vaccination , Young Adult
7.
Cell Host Microbe ; 29(4): 529-539.e3, 2021 04 14.
Article in English | MEDLINE | ID: covidwho-1309188

ABSTRACT

All current vaccines for COVID-19 utilize ancestral SARS-CoV-2 spike with the goal of generating protective neutralizing antibodies. The recent emergence and rapid spread of several SARS-CoV-2 variants carrying multiple spike mutations raise concerns about possible immune escape. One variant, first identified in the United Kingdom (B.1.1.7, also called 20I/501Y.V1), contains eight spike mutations with potential to impact antibody therapy, vaccine efficacy, and risk of reinfection. Here, we show that B.1.1.7 remains sensitive to neutralization, albeit at moderately reduced levels (∼sim;2-fold), by serum samples from convalescent individuals and recipients of an mRNA vaccine (mRNA-1273, Moderna) and a protein nanoparticle vaccine (NVX-CoV2373, Novavax). A subset of monoclonal antibodies to the receptor binding domain (RBD) of spike are less effective against the variant, while others are largely unaffected. These findings indicate that variant B.1.1.7 is unlikely to be a major concern for current vaccines or for an increased risk of reinfection.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19 Vaccines/immunology , SARS-CoV-2/immunology , 2019-nCoV Vaccine mRNA-1273 , Adolescent , Adult , Aged , Aged, 80 and over , Antibodies, Monoclonal/immunology , Female , Humans , Male , Middle Aged , Mutation , Neutralization Tests , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Young Adult
8.
J Clin Microbiol ; 59(7): e0051421, 2021 06 18.
Article in English | MEDLINE | ID: covidwho-1276889

ABSTRACT

Accurate SARS-CoV-2 serological assays are critical for COVID-19 serosurveillance. However, previous studies have indicated possible cross-reactivity of these assays, including in areas where malaria is endemic. We tested 213 well-characterized prepandemic samples from Nigeria using two SARS-CoV-2 serological assays, Abbott Architect IgG and Euroimmun NCP IgG assay, both targeting SARS-CoV-2 nucleocapsid protein. To assess antibody binding strength, an avidity assay was performed on these samples and on plasma from SARS-CoV-2 PCR-positive persons. Thirteen (6.1%) of 212 samples run on the Abbott assay and 38 (17.8%) of 213 run on the Euroimmun assay were positive. Anti-Plasmodium IgG levels were significantly higher among false positives for both Abbott and Euroimmun; no association was found with active Plasmodium falciparum infection. An avidity assay using various concentrations of urea wash in the Euroimmun assay reduced loosely bound IgG: of 37 positive/borderline prepandemic samples, 46%, 86%, 89%, and 97% became negative using 2 M, 4 M, 5 M, and 8 M urea washes, respectively. The wash slightly reduced avidity of antibodies from SARS-CoV-2 patients within 28 days of PCR confirmation; thereafter, avidity increased for all urea concentrations except 8 M. This validation found moderate to substantial cross-reactivity on two SARS-CoV-2 serological assays using samples from a setting where malaria is endemic. A simple urea wash appeared to alleviate issues of cross-reactivity.


Subject(s)
COVID-19 , Malaria , Antibodies, Viral , Humans , Malaria/diagnosis , Nigeria , SARS-CoV-2 , Sensitivity and Specificity
9.
Emerg Microbes Infect ; 10(1): 1390-1403, 2021 Dec.
Article in English | MEDLINE | ID: covidwho-1268055

ABSTRACT

Global concerns arose as the emerged and rapidly spreading SARS-CoV-2 variants might escape host immunity induced by vaccination. In this study, a heterologous prime-boost immunization strategy for COVID-19 was designed to prime with a DNA vaccine encoding wild type (WT) spike protein receptor-binding domain (RBD) followed by S1 protein-based vaccine in rabbits. Four vaccine-elicited rabbit monoclonal antibodies (RmAbs), including 1H1, 9H1, 7G5, and 5E1, were isolated for biophysical property, neutralization potency and sequence analysis. All RmAbs recognized RBD or S1 protein with KD in the low nM or sub nM range. 1H1 and 9H1, but neither 7G5 nor 5E1, can bind to all RBD protein variants derived from B.1.351. All four RmAbs were able to neutralize wild type (WT) SARS-CoV-2 strain in pseudovirus assay, and 1H1 and 9H1 could neutralize the SARS-CoV-2 WT authentic virus with IC50 values of 0.136 and 0.026 µg/mL, respectively. Notably, 1H1 was able to neutralize all 6 emerging SARS-CoV-2 variants tested including D614G, B.1.1.7, B.1.429, P.1, B.1.526, and B.1.351 variants, and 5E1 could neutralize against the above 5 variants except P.1. Epitope binning analysis revealed that 9H1, 5E1 and 1H1 recognized distinct epitopes, while 9H1 and 7G5 may have overlapping but not identical epitope. In conclusion, DNA priming protein boost vaccination was an effective strategy to induce RmAbs with potent neutralization capability against not only SARS-CoV-2 WT strain but also emergent variants, which may provide a new avenue for effective therapeutics and point-of-care diagnostic measures.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Genetic Variation , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics , Vaccines, DNA/immunology , Animals , Antibodies, Viral/blood , Epitopes , Humans , Immunization, Secondary , Protein Domains/immunology , Protein Domains/physiology , Rabbits , SARS-CoV-2/immunology , Vaccination , Vaccines, Synthetic , Virus Attachment
10.
J Biol Regul Homeost Agents ; 35(3): 839-842, 2021.
Article in English | MEDLINE | ID: covidwho-1262732

ABSTRACT

Anaphylaxis is a severe multisystem reaction that occurs rapidly after the introduction of an antigen that would otherwise be a harmless substance. It is characterized by airway and respiratory problems, cardiovascular collapse, mucosal inflammation, and other complications, all severe symptoms that can cause death. IgE-dependent anaphylaxis involves mast cells (MCs) which are the main sources of biologically active mediators that contribute to the pathological and lethal phenomena that can occur in anaphylaxis. Antibody-mediated anaphylaxis can follow multiple pathways such as that mediated by MCs carrying the FcεRI receptor, which can be activated by very small amounts of antigen including a vaccine antigen and trigger an anaphylactic reaction. In addition, anaphylaxis can also be provoked by high concentrations of IgG antibodies that bind to the FcγR receptor present on basophils, neutrophils, macrophages and MCs. For this reason, the IgG concentration should be kept under control in vaccinations. Activation of MCs is a major cause of anaphylaxis, which requires immediate treatment with epinephrine to arrest severe lethal symptoms. MCs are activated through the antigen binding and cross-linking of IgE with release of mediators such as histamine, proteases, prostaglandins, leukotrienes and inflammatory cytokines. The release of these compounds causes nausea, vomiting, hives, wheezing, flushing, tachycardia, hypotension, laryngeal edema, and cardiovascular collapse. mRNA and viral vector vaccines have been cleared by the United States, Food and Drug Administration (FDA), generating hope of prevention and cure for COVID-19 around the world. Scientists advise against giving the vaccine to individuals who have had a previous history of anaphylaxis. The US Centers for Disease Control and Prevention (CDC) advises people with a previous history of any immediate allergic reaction to remain under observation for approximately 30 minutes after COVID-19 vaccination. To date, vaccines that prevent SARS-CoV-2 infection have not raised major concerns of severe allergic reactions, although, in some cases, pain and redness at the injection site and fever have occurred after administration of the vaccine. These reactions occur in the first 24-48 hours after vaccination. It has been reported that probable forms of anaphylaxis could also occur, especially in women approximately 40 years of age. But after tens of millions of vaccinations, only a few patients had this severe reaction with a low incidence. Anaphylactic and severe allergic reactions can also occur to any component of the vaccine including polysorbates and polyethylene glycol. To date, there is no precise information on allergic reactions to COVID-19 vaccines. Individuals with MCs and complement with higher activation than others may be at greater allergic risk. Moreover, the reactions called anaphylactoids, are those not mediated by IgE because they do not involve this antibody and can also occur in COVID-19 vaccination. These not-IgE-mediated reactions occur through direct activation of MCs and complement with tryptase production, but to a lesser extent than IgE-mediated anaphylaxis. However, at the moment it is not known exactly which component of the vaccine causes the allergic reaction and which vaccine causes the most side effects, including anaphylaxis. Thus, individuals who have a known allergy to any component of the vaccine should not be vaccinated. However, should an anaphylactic reaction occur, this requires immediate treatment with epinephrine to arrest severe lethal symptoms. In conclusion, the purpose of this editorial is to encourage the population to be vaccinated in order to extinguish this global pandemic that is afflicting the world population, and to reassure individuals that anaphylactic reactions do not occur with a higher incidence than other vaccinations.


Subject(s)
Anaphylaxis , COVID-19 , COVID-19 Vaccines , Female , Humans , SARS-CoV-2 , Vaccination/adverse effects
11.
Sci Transl Med ; 13(600)2021 06 30.
Article in English | MEDLINE | ID: covidwho-1262380

ABSTRACT

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with mutations in key antibody epitopes has raised concerns that antigenic evolution could erode adaptive immunity elicited by prior infection or vaccination. The susceptibility of immunity to viral evolution is shaped in part by the breadth of epitopes targeted by antibodies elicited by vaccination or natural infection. To investigate how human antibody responses to vaccines are influenced by viral mutations, we used deep mutational scanning to compare the specificity of polyclonal antibodies elicited by either two doses of the mRNA-1273 COVID-19 vaccine or natural infection with SARS-CoV-2. The neutralizing activity of vaccine-elicited antibodies was more targeted to the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein compared to antibodies elicited by natural infection. However, within the RBD, binding of vaccine-elicited antibodies was more broadly distributed across epitopes compared to infection-elicited antibodies. This greater binding breadth means that single RBD mutations have less impact on neutralization by vaccine sera compared to convalescent sera. Therefore, antibody immunity acquired by natural infection or different modes of vaccination may have a differing susceptibility to erosion by SARS-CoV-2 evolution.


Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Neutralizing , Antibodies, Viral , COVID-19/therapy , COVID-19 Vaccines , Humans , Immunization, Passive , RNA, Messenger , Spike Glycoprotein, Coronavirus , Vaccination
12.
J Biomed Sci ; 28(1): 43, 2021 Jun 07.
Article in English | MEDLINE | ID: covidwho-1261273

ABSTRACT

BACKGROUND: Coronavirus disease 19 (COVID-19) first appeared in the city of Wuhan, in the Hubei province of China. Since its emergence, the COVID-19-causing virus, SARS-CoV-2, has been rapidly transmitted around the globe, overwhelming the medical care systems in many countries and leading to more than 3.3 million deaths. Identification of immunological epitopes on the virus would be highly useful for the development of diagnostic tools and vaccines that will be critical to limiting further spread of COVID-19. METHODS: To find disease-specific B-cell epitopes that correspond to or mimic natural epitopes, we used phage display technology to determine the targets of specific antibodies present in the sera of immune-responsive COVID-19 patients. Enzyme-linked immunosorbent assays were further applied to assess competitive antibody binding and serological detection. VaxiJen, BepiPred-2.0 and DiscoTope 2.0 were utilized for B-cell epitope prediction. PyMOL was used for protein structural analysis. RESULTS: 36 enriched peptides were identified by biopanning with antibodies from two COVID-19 patients; the peptides 4 motifs with consensus residues corresponding to two potential B-cell epitopes on SARS-CoV-2 viral proteins. The putative epitopes and hit peptides were then synthesized for validation by competitive antibody binding and serological detection. CONCLUSIONS: The identified B-cell epitopes on SARS-CoV-2 may aid investigations into COVID-19 pathogenesis and facilitate the development of epitope-based serological diagnostics and vaccines.


Subject(s)
COVID-19 , Epitopes, B-Lymphocyte , Peptide Library , SARS-CoV-2 , Viral Proteins , COVID-19/genetics , COVID-19/immunology , Epitopes, B-Lymphocyte/genetics , Epitopes, B-Lymphocyte/immunology , Humans , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Viral Proteins/genetics , Viral Proteins/immunology
13.
Nature ; 595(7868): 572-577, 2021 07.
Article in English | MEDLINE | ID: covidwho-1246378

ABSTRACT

BNT162b2, a nucleoside-modified mRNA formulated in lipid nanoparticles that encodes the SARS-CoV-2 spike glycoprotein (S) stabilized in its prefusion conformation, has demonstrated 95% efficacy in preventing COVID-191. Here we extend a previous phase-I/II trial report2 by presenting data on the immune response induced by BNT162b2 prime-boost vaccination from an additional phase-I/II trial in healthy adults (18-55 years old). BNT162b2 elicited strong antibody responses: at one week after the boost, SARS-CoV-2 serum geometric mean 50% neutralizing titres were up to 3.3-fold above those observed in samples from individuals who had recovered from COVID-19. Sera elicited by BNT162b2 neutralized 22 pseudoviruses bearing the S of different SARS-CoV-2 variants. Most participants had a strong response of IFNγ+ or IL-2+ CD8+ and CD4+ T helper type 1 cells, which was detectable throughout the full observation period of nine weeks following the boost. Using peptide-MHC multimer technology, we identified several BNT162b2-induced epitopes that were presented by frequent MHC alleles and conserved in mutant strains. One week after the boost, epitope-specific CD8+ T cells of the early-differentiated effector-memory phenotype comprised 0.02-2.92% of total circulating CD8+ T cells and were detectable (0.01-0.28%) eight weeks later. In summary, BNT162b2 elicits an adaptive humoral and poly-specific cellular immune response against epitopes that are conserved in a broad range of variants, at well-tolerated doses.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19 Vaccines/immunology , COVID-19/immunology , SARS-CoV-2/immunology , T-Lymphocytes/immunology , Adolescent , Adult , CD8-Positive T-Lymphocytes/immunology , COVID-19/virology , COVID-19 Vaccines/administration & dosage , COVID-19 Vaccines/adverse effects , Epitopes, T-Lymphocyte/immunology , Female , Humans , Immunoglobulin G/immunology , Immunologic Memory , Interferon-gamma/immunology , Interleukin-2/immunology , Male , Middle Aged , SARS-CoV-2/chemistry , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , Th1 Cells/immunology , Young Adult
14.
Res Sq ; 2021 Apr 22.
Article in English | MEDLINE | ID: covidwho-1237035

ABSTRACT

The emergency use authorization of two COVID-19 mRNA vaccines in less than a year since the emergence of SARS-CoV-2, represents a landmark in vaccinology1,2. Yet, how mRNA vaccines stimulate the immune system to elicit protective immune responses is unknown. Here we used a systems biological approach to comprehensively profile the innate and adaptive immune responses in 56 healthy volunteers vaccinated with the Pfizer-BioNTech mRNA vaccine. Vaccination resulted in robust production of neutralizing antibodies (nAbs) against the parent strain and the variant of concern, B.1.351, but no induction of autoantibodies, and significant increases in antigen-specific polyfunctional CD4 and CD8 T cells after the second dose. The innate response induced within the first 2 days of booster vaccination was profoundly increased, relative to the response at corresponding times after priming. Thus, there was a striking increase in the: (i) frequency of CD14+CD16+ inflammatory monocytes; (ii) concentration of IFN- y in the plasma, which correlated with enhanced pSTAT3 and pSTAT1 levels in monocytes and T cells; and (iii) transcriptional signatures of innate responses characteristic of antiviral vaccine responses against pandemic influenza, HIV and Ebola, within 2 days following booster vaccination compared to primary vaccination. Consistent with these observations, single-cell transcriptomics analysis of 242,479 leukocytes demonstrated a ~100-fold increase in the frequency of a myeloid cluster, enriched in a signature of interferon-response transcription factors (TFs) and reduced in AP-1 TFs, one day after secondary immunization, at day 21. Finally, we delineated distinct molecular pathways of innate activation that correlate with CD8 T cell and nAb responses and identified an early monocyte-related signature that was associated with the breadth of the nAb response against the B1.351 variant strain. Collectively, these data provide insights into the immune responses induced by mRNA vaccines and demonstrate their capacity to stimulate an enhanced innate response following booster immunization.

15.
Front Immunol ; 12: 647934, 2021.
Article in English | MEDLINE | ID: covidwho-1229176

ABSTRACT

SARS-CoV-2, the novel coronavirus responsible for the ongoing COVID-19 pandemic, has been spreading rampantly. The global scientific community has responded rapidly to understand immune correlates of protection to develop vaccines and immunotherapeutics against the virus. The major goal of this mini review is to summarize current understanding of the structural landscape of neutralizing antibodies (nAbs) that target the receptor binding domain (RBD) of viral spike (S) glycoprotein. The RBD plays a critical role in the very first step of the virus life cycle. Better understanding of where and how nAbs bind the RBD should enable identification of sites of vulnerability and facilitate better vaccine design and formulation of immunotherapeutics. Towards this goal, we compiled 38 RBD-binding nAbs with known structures. Review of these nAb structures showed that (1) nAbs can be divided into five general clusters, (2) there are distinct non-neutralizing faces on the RBD, and (3) maximum of potentially four nAbs could bind the RBD simultaneously. Since most of these nAbs were isolated from virus-infected patients, additional analyses of vaccine-induced nAbs could facilitate development of improved vaccines.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/immunology , Epitopes/immunology , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Binding Sites , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19 Vaccines/immunology , COVID-19 Vaccines/therapeutic use , Humans , Pandemics , Structure-Activity Relationship
16.
J Clin Invest ; 131(12)2021 06 15.
Article in English | MEDLINE | ID: covidwho-1218257

ABSTRACT

BACKGROUNDThe COVID-19 vaccines currently in use require 2 doses to achieve optimal protection. Currently, there is no indication as to whether individuals who have been exposed to SARS-CoV-2 should be vaccinated, or whether they should receive 1 or 2 vaccine doses.METHODSWe tested the antibody response developed after administration of the Pfizer/BioNTech vaccine in 124 health care professionals, of whom 57 had a previous history of SARS-CoV-2 exposure with or without symptoms.RESULTSPostvaccine antibodies in SARS-CoV-2-exposed individuals increased exponentially within 5 to 18 days after the first dose compared to naive subjects (P < 0.0001). In a multivariate linear regression (LR) model we showed that the antibody response depended on the IgG prevaccine titer and on the exposure to SARS-CoV-2. In symptomatic SARS-CoV-2-exposed individuals, IgG reached a plateau after the second dose, and those who voluntarily refrained from receiving the second dose (n = 7) retained their antibody response. Gastrointestinal symptoms, muscle pain, and fever markedly positively correlated with increased IgG responses. By contrast, all asymptomatic/paucisymptomatic and unexposed individuals showed an important increase after the second dose.CONCLUSIONOne vaccine dose is sufficient in symptomatic SARS-CoV-2-exposed subjects to reach a high titer of antibodies, suggesting no need for a second dose, particularly in light of current vaccine shortage.TRIAL REGISTRATIONClinicalTrials.gov NCT04387929.FUNDINGDolce & Gabbana and the Italian Ministry of Health (Ricerca corrente).


Subject(s)
Antibodies, Viral , Antibody Formation/drug effects , COVID-19 Vaccines/administration & dosage , COVID-19 , SARS-CoV-2 , Adult , Antibodies, Viral/blood , Antibodies, Viral/immunology , COVID-19/blood , COVID-19/immunology , COVID-19 Vaccines/immunology , Female , Humans , Male , Middle Aged , SARS-CoV-2/immunology , SARS-CoV-2/metabolism
17.
Food Chem Toxicol ; 152: 112239, 2021 Jun.
Article in English | MEDLINE | ID: covidwho-1202176

ABSTRACT

The outbreak of COVID-19 has posed a serious threat to global public health. Vaccination may be the most effective way to prevent and control the spread of the virus. The safety of vaccines is the focus of preclinical research, and the repeated dose toxicity test is the key safety test to evaluate the vaccine before clinical trials. The purpose of this study was (i) to observe the toxicity and severity of an inactivated SARS-CoV-2 vaccine (Vero cells) in rodent Sprague Dawley rats after multiple intramuscular injections under the premise of Good Laboratory Practice principles and (ii) to provide a basis for the formulation of a clinical trial scheme. The results showed that all animals in the experimental group were in good condition, no regular changes related to the vaccine were found in the detection of various toxicological indexes, and no noticeable stimulating reaction related to the vaccine was found in the injected local tissues. The neutralizing antibodies in the low- and high-dose vaccine groups began to appear 14 days after the last administration. In the negative control group, no neutralizing antibodies were observed from the administration period to the recovery period. Therefore, the repeated administration toxicity test of the inactivated SARS-CoV-2 vaccine (Vero cells) in Sprague Dawley rats showed no obvious toxic reaction. It was preliminarily confirmed that the vaccine can stimulate production of neutralizing antibodies and is safe in Sprague Dawley rats.


Subject(s)
Antibodies, Neutralizing/blood , Antibodies, Viral/blood , COVID-19 Vaccines/immunology , Animals , COVID-19 , COVID-19 Vaccines/toxicity , Female , Male , Rats, Sprague-Dawley , Toxicity Tests , Vaccines, Inactivated/immunology , Vaccines, Inactivated/toxicity
18.
Curr Opin Infect Dis ; 34(3): 181-186, 2021 06 01.
Article in English | MEDLINE | ID: covidwho-1201884

ABSTRACT

PURPOSE OF REVIEW: Despite its crucial role in protection against viral infections, mucosal immunity has been largely understudied in the context of coronavirus disease 2019 (COVID-19). This review outlines the current evidence about the role of mucosal immune responses in the clearance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, as well as potential mucosal mechanisms of protection against (re-)infection. RECENT FINDINGS: The angiotensin-converting enzyme 2 cellular entry receptor for SARS-CoV-2 is most highly expressed in the upper respiratory tract and most SARS-CoV-2 shedding occurs from the upper respiratory tract. Viral shedding peaks early during infection around the onset of symptoms, before dropping rapidly in most individuals within 7 days of symptom onset, suggesting mucosal inhibition of viral infection. Serum and mucosal immunoglobulin G and immunoglobulin M responses were found to be strongly correlated in infected patients, whereas correlations were much weaker for immunoglobulin A (IgA). Mucosal IgA responses have been detected in infected cases in the absence of serum antibody responses, with mucosal antibody levels correlating strongly with virus neutralization. Bulk and single-cell RNA sequencing analysis of nasopharyngeal swabs and bronchoalveolar lavage samples of COVID-19 patients revealed the induction of mucosal chemokine and cytokine genes, complement pathways, Janus Kinase/Signal Transducer and Activator of Transcription signaling and cytotoxic T cells. SUMMARY: Although most clinical studies focus on antibodies and cellular immunity in peripheral blood, mucosal immune responses in the respiratory tract play a key role in the early restriction of viral replication and the clearance of SARS-CoV-2. Identification of mucosal biomarkers associated with viral clearance will allow monitoring of infection-induced immunity. Further studies are needed to understand how the systemic immunological endpoints measured in vaccination studies translate to mucosal protection against SARS-CoV-2 infection.


Subject(s)
Antibodies, Viral/immunology , COVID-19/immunology , Immunity, Mucosal , Immunoglobulin A/immunology , Virus Shedding , COVID-19/prevention & control , Humans , Immunoglobulin A/blood , SARS-CoV-2/immunology , Vaccination
19.
Monoclon Antib Immunodiagn Immunother ; 40(2): 36-49, 2021 Apr.
Article in English | MEDLINE | ID: covidwho-1201076

ABSTRACT

The dawn of the 20th century saw the formative years of developments in immunology. In particular, immunochemistry, specifically pertaining to antibodies, was extensively studied. These studies laid the foundations for employing antibodies in a variety of ways. Not surprisingly, antibodies have been used for applications ranging from biomedical research to disease diagnostics and therapeutics to evaluation of immune responses during natural infection and those elicited by vaccines. Despite recent advancements in cellular immunology and the excitement of T cell therapy, use of antibodies represents a large proportion of immunotherapeutic approaches as well as clinical interventions. Polyclonal antibodies in the form of plasma or sera continue to be used to treat a number of diseases, including autoimmune disorders, cancers, and infectious diseases. Historically, antisera to toxins have been the longest serving biotherapeutics. In addition, intravenous immunoglobulins (IVIg) have been extensively used to treat not only immunodeficiency conditions but also autoimmune disorders. Beyond the simplistic suppositions of their action, the IVIg have also unraveled the immune regulatory and homeostatic ramifications of their use. The advent of monoclonal antibodies (MAbs), on the other hand, has provided a clear pathway for their development as drug molecules. MAbs have found a clear place in the treatment of cancers and extending lives and have been used in a variety of other conditions. In this review, we capture the important developments in the therapeutic applications of antibodies to alleviate disease, with a focus on some of the recent developments.


Subject(s)
Antibodies, Monoclonal/therapeutic use , COVID-19/therapy , Diphtheria/therapy , Neoplasms/therapy , Animals , Antibodies, Monoclonal/immunology , COVID-19/immunology , COVID-19/virology , Cell- and Tissue-Based Therapy , Diphtheria/immunology , Humans , Immunoglobulins/immunology , Immunoglobulins/therapeutic use , Neoplasms/immunology , SARS-CoV-2/immunology , SARS-CoV-2/pathogenicity , T-Lymphocytes/immunology
20.
PLoS Pathog ; 17(4): e1009064, 2021 04.
Article in English | MEDLINE | ID: covidwho-1197395

ABSTRACT

Vaccines of outstanding efficiency, safety, and public acceptance are needed to halt the current SARS-CoV-2 pandemic. Concerns include potential side effects caused by the antigen itself and safety of viral DNA and RNA delivery vectors. The large SARS-CoV-2 spike (S) protein is the main target of current COVID-19 vaccine candidates but can induce non-neutralizing antibodies, which might cause vaccination-induced complications or enhancement of COVID-19 disease. Besides, encoding of a functional S in replication-competent virus vector vaccines may result in the emergence of viruses with altered or expanded tropism. Here, we have developed a safe single round rhabdovirus replicon vaccine platform for enhanced presentation of the S receptor-binding domain (RBD). Structure-guided design was employed to build a chimeric minispike comprising the globular RBD linked to a transmembrane stem-anchor sequence derived from rabies virus (RABV) glycoprotein (G). Vesicular stomatitis virus (VSV) and RABV replicons encoding the minispike not only allowed expression of the antigen at the cell surface but also incorporation into the envelope of secreted non-infectious particles, thus combining classic vector-driven antigen expression and particulate virus-like particle (VLP) presentation. A single dose of a prototype replicon vaccine complemented with VSV G, VSVΔG-minispike-eGFP (G), stimulated high titers of SARS-CoV-2 neutralizing antibodies in mice, equivalent to those found in COVID-19 patients, and protected transgenic K18-hACE2 mice from COVID-19-like disease. Homologous boost immunization further enhanced virus neutralizing activity. The results demonstrate that non-spreading rhabdovirus RNA replicons expressing minispike proteins represent effective and safe alternatives to vaccination approaches using replication-competent viruses and/or the entire S antigen.


Subject(s)
Antibodies, Neutralizing/blood , Antibodies, Viral/blood , COVID-19 Vaccines/administration & dosage , COVID-19/prevention & control , Immunization/methods , SARS-CoV-2/immunology , Vaccines, Virus-Like Particle/administration & dosage , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/immunology , COVID-19/virology , Female , HEK293 Cells , Humans , Mice , Mice, Inbred C57BL
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