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1.
Nat Chem Biol ; 2022 Jul 25.
Article in English | MEDLINE | ID: covidwho-1960395

ABSTRACT

SARS-CoV-2 entry into cells requires specific host proteases; however, no successful in vivo applications of host protease inhibitors have yet been reported for treatment of SARS-CoV-2 pathogenesis. Here we describe a chemically engineered nanosystem encapsulating CRISPR-Cas13d, developed to specifically target lung protease cathepsin L (Ctsl) messenger RNA to block SARS-CoV-2 infection in mice. We show that this nanosystem decreases lung Ctsl expression in normal mice efficiently, specifically and safely. We further show that this approach extends survival of mice lethally infected with SARS-CoV-2, correlating with decreased lung virus burden, reduced expression of proinflammatory cytokines/chemokines and diminished severity of pulmonary interstitial inflammation. Postinfection treatment by this nanosystem dramatically lowers the lung virus burden and alleviates virus-induced pathological changes. Our results indicate that targeting lung protease mRNA by Cas13d nanosystem represents a unique strategy for controlling SARS-CoV-2 infection and demonstrate that CRISPR can be used as a potential treatment for SARS-CoV-2 infection.

2.
Sci Immunol ; : eadd4853, 2022 Jul 19.
Article in English | MEDLINE | ID: covidwho-1949945

ABSTRACT

SARS-CoV-2 mRNA vaccination induces robust humoral and cellular immunity in the circulation; however, it is currently unknown whether it elicits effective immune responses in the respiratory tract, particularly against variants of concern (VOCs), including Omicron. We compared the SARS-CoV-2 S-specific total and neutralizing antibody responses, and B and T cell immunity, in the bronchoalveolar lavage fluid (BAL) and blood of COVID-19 vaccinated individuals and hospitalized patients. Vaccinated individuals had significantly lower levels of neutralizing antibody against D614G, Delta (B.1.617.2) and Omicron BA.1.1 in the BAL compared to COVID-19 convalescents, despite robust S-specific antibody responses in the blood. Furthermore, mRNA vaccination induced circulating S-specific B and T cell immunity, but in contrast to COVID-19 convalescents, these responses were absent in the BAL of vaccinated individuals. Using a mouse immunization model, we demonstrated that systemic mRNA vaccination alone induced weak respiratory mucosal neutralizing antibody responses, especially against SARS-CoV-2 Omicron BA.1.1 in mice; however, a combination of systemic mRNA vaccination plus mucosal adenovirus-S immunization induced strong neutralizing antibody responses, not only against the ancestral virus but also the Omicron BA.1.1 variant. Together, our study supports the contention that the current COVID-19 vaccines are highly effective against severe disease development, likely through recruiting circulating B and T cell responses during re-infection, but offer limited protection against breakthrough infection, especially by Omicron sublineage. Hence, mucosal booster vaccination is needed to establish robust sterilizing immunity in the respiratory tract against SARS-CoV-2, including infection by Omicron sublineage and future VOCs.

4.
Cell Host Microbe ; 2022 Apr 25.
Article in English | MEDLINE | ID: covidwho-1803742

ABSTRACT

Recent reports of SARS-CoV-2 Omicron variant sub-lineages, BA.1, BA.1.1, and BA.2, have reignited concern over potential escape from vaccine- and infection-induced immunity. We examine the sensitivity of these sub-lineages and other major variants to neutralizing antibodies from mRNA-vaccinated and boosted individuals, as well as recovered COVID-19 patients, including those infected with Omicron. We find that all Omicron sub-lineages, especially BA.1 and BA.1.1, exhibit substantial immune escape that is largely overcome by mRNA vaccine booster doses. While Omicron BA.1.1 escapes almost completely from neutralization by early-pandemic COVID-19 patient sera and to a lesser extent from sera of Delta-infected patients, BA.1.1 is sensitive to Omicron-infected patient sera. Critically, all Omicron sub-lineages, including BA.2, are comparably neutralized by Omicron patient sera. These results highlight the importance of booster vaccine doses for protection against all Omicron variants and provide insight into the immunity from natural infection against Omicron sub-lineages.

5.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-332613

ABSTRACT

Vaccines against SARS-CoV-2 that induce mucosal immunity capable of preventing infection and disease remain urgently needed. We show that intramuscular priming of mice with an alum and BcfA-adjuvanted Spike subunit vaccine, followed by a BcfA-adjuvanted mucosal booster, generated Th17 polarized tissue resident CD4+ T cells, and mucosal and serum antibodies. The serum antibodies efficiently neutralized SARS-CoV-2 and its Delta variant, suggesting cross-protection against a recent variant of concern (VOC). Immunization with this heterologous vaccine prevented weight loss following challenge with mouse-adapted SARS-CoV-2 and reduced viral replication in the nose and lungs. Histopathology showed a strong leukocyte and polymorphonuclear (PMN) cell infiltrate without epithelial damage in mice immunized with BcfA-containing vaccines. In contrast, viral load was not reduced in the upper respiratory tract of IL-17 knockout mice immunized with the same formulation, suggesting that the Th17 polarized T cell responses are critical for protection. We show that vaccines adjuvanted with alum and BcfA, delivered through a heterologous prime-pull regimen, protect against SARS-CoV-2 infection without causing enhanced respiratory disease.

6.
Multiple sclerosis journal - experimental, translational and clinical ; 8(1), 2022.
Article in English | EuropePMC | ID: covidwho-1755751

ABSTRACT

Background Patients with multiple sclerosis (pwMS) are often treated with disease modifying therapies (DMT) with immunomodulatory effects. This is of particular concern following the development of several vaccines to combat coronavirus disease 19 (COVD-19), a potentially fatal illness caused by SARS-CoV-2. Objectives To determine the efficacy of SARS-CoV-2 vaccination in pwMS and the impact of disease modifying therapies (DMT) on vaccine response. Methods This is a prospective longitudinal study in pwMS. Longitudinal serum samples were obtained prior to, and after SARS-CoV-2 mRNA vaccination. A novel neutralizing antibody (nAb) assay was used to determine nAbs titres against SARS-CoV-2 spike. Results We observed that (1) pwMS on B-cell depleting therapies exhibited reduced response to vaccination compared to other pwMS, correlating with time from last anti-CD20 infusion, (2) prior COVID-19 illness, DMT category, and pyramidal function were significant predictors of vaccine responsiveness, and (3) circulating absolute lymphocyte count (ALC) and IgG levels correlated with nAb levels. Conclusions We demonstrate that pwMS exhibit reduced nAb response to mRNA vaccination dependent on DMT status and identify predictive biomarkers for vaccine efficacy. We conclude that additional vaccination strategies may be necessary to achieve protective immunity in pwMS.

7.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-330744

ABSTRACT

The impact of SARS-CoV2 vaccination in cancer patients remains incompletely understood given the heterogeneity of cancer and cancer therapies. We assessed vaccine-induced antibody response to the SARS-CoV2 Omicron (B.1.1.529) variant in 57 patients with B cell malignancies with and without active B cell-targeted therapy. Ancestral- and Omicron- reactive antibody levels were determined by ELISA and neutralization assays. In over one third of vaccinated patients at the pre-booster timepoint, there were no ELISA-detectable antibodies against either the ancestral strain or Omicron variant. The lack of vaccine-induced antibodies was predominantly in patients receiving active therapy such as anti-CD20 monoclonal antibody (mAb) or Bruton's tyrosine kinase inhibitors (BTKi). While booster immunization was able to induce detectable antibodies in a small fraction of seronegative patients, the benefit was disproportionately evident in patients not on active therapy. Importantly, in patients with post-booster ELISA-detectable antibodies, there was a positive correlation of antibody levels against the ancestral strain and Omicron variant. Booster immunization increased overall antibody levels, including neutralizing antibody titers against the ancestral strain and Omicron variant;however, predominantly in patients without active therapy. Furthermore, ancestral strain neutralizing antibody titers were about 5-fold higher in comparison with those to Omicron, suggesting that even with booster administration, there may be reduced protection against the Omicron variant. Interestingly, in almost all patients regardless of active therapy, including those unable to generate detectable antibodies against SARS-CoV2 spike, we observed comparable levels of EBV, influenza, and common cold coronavirus reactive antibodies demonstrating that B cell-targeting therapies primarily impair de novo but not pre-existing antibody levels. These findings suggest that patients with B cell malignancies on active therapy may be at disproportionately higher risk to new versus endemic viral infection and suggest utility for vaccination prior to B cell-targeted therapy.

8.
EuropePMC;
Preprint in English | EuropePMC | ID: ppcovidwho-327171

ABSTRACT

SARS-CoV-2 mRNA vaccination induces robust humoral and cellular immunity in the circulation;however, it is currently unknown whether it elicits effective immune responses in the respiratory tract, particularly against variants of concern (VOCs), including Omicron. We compared the SARS-CoV-2 S-specific total and neutralizing antibody (Ab) responses, and B and T cell immunity, in the bronchoalveolar lavage fluid (BAL) and blood of COVID-19 vaccinated individuals and hospitalized patients. Vaccinated individuals had significantly lower levels of neutralizing Ab against D614G, Delta and Omicron in the BAL compared to COVID-19 convalescents, despite robust S-specific Ab responses in the blood. Further, mRNA vaccination induced significant circulating S-specific B and T cell immunity, but in contrast to COVID-19 convalescents, these responses were absent in the BAL of vaccinated individuals. Using an animal immunization model, we demonstrate that systemic mRNA vaccination alone induced weak respiratory mucosal neutralizing Ab responses, especially against SARS-CoV-2 Omicron;however, a combination of systemic mRNA vaccination plus mucosal adenovirus-S immunization induced strong neutralizing Ab response, not only against the ancestral virus but also the Omicron variant. Together, our study supports the contention that the current COVID-19 vaccines are highly effective against severe disease development, likely through recruiting circulating B and T cell responses during re-infection, but offer limited protection against breakthrough infection, especially by Omicron. Hence, mucosal booster vaccination is needed to establish robust sterilizing immunity in the respiratory tract against SARS-CoV-2, including infection by Omicron and future variants.

9.
Sci Transl Med ; 14(637): eabn8057, 2022 03 23.
Article in English | MEDLINE | ID: covidwho-1685483

ABSTRACT

The waning efficacy of SARS-CoV-2 vaccines, combined with the continued emergence of variants resistant to vaccine-induced immunity, has reignited debate over the need for booster vaccine doses. To address this, we examined the neutralizing antibody response against the spike protein of five major SARS-CoV-2 variants, D614G, Alpha (B.1.1.7), Beta (B.1.351), Delta (B.1.617.2), and Omicron (B.1.1.529), in health care workers (HCWs) vaccinated with SARS-CoV-2 mRNA vaccines. Serum samples were collected before vaccination, 3 weeks after first vaccination, 1 month after second vaccination, and 6 months after second vaccination. Minimal neutralizing antibody titers were detected against Omicron pseudovirus at all four time points, including for most patients who had SARS-CoV-2 breakthrough infections. Neutralizing antibody titers against all other variant spike protein-bearing pseudoviruses declined markedly from 1 to 6 months after the second mRNA vaccine dose, although SARS-CoV-2 infection boosted vaccine responses. In addition, mRNA-1273-vaccinated HCWs exhibited about twofold higher neutralizing antibody titers than BNT162b2-vaccinated HCWs. Together, these results demonstrate possible waning of antibody-mediated protection against SARS-CoV-2 variants that is dependent on prior infection status and the mRNA vaccine received. They also show that the Omicron variant spike protein can almost completely escape from neutralizing antibodies elicited in recipients of only two mRNA vaccine doses.


Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Neutralizing , Antibodies, Viral , COVID-19/prevention & control , COVID-19 Vaccines , Humans , RNA, Messenger/genetics , Vaccination , Vaccines, Synthetic
11.
Proc Natl Acad Sci U S A ; 119(1)2022 01 04.
Article in English | MEDLINE | ID: covidwho-1599544

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly transmissible coronavirus responsible for the global COVID-19 pandemic. Herein, we provide evidence that SARS-CoV-2 spreads through cell-cell contact in cultures, mediated by the spike glycoprotein. SARS-CoV-2 spike is more efficient in facilitating cell-to-cell transmission than is SARS-CoV spike, which reflects, in part, their differential cell-cell fusion activity. Interestingly, treatment of cocultured cells with endosomal entry inhibitors impairs cell-to-cell transmission, implicating endosomal membrane fusion as an underlying mechanism. Compared with cell-free infection, cell-to-cell transmission of SARS-CoV-2 is refractory to inhibition by neutralizing antibody or convalescent sera of COVID-19 patients. While angiotensin-converting enzyme 2 enhances cell-to-cell transmission, we find that it is not absolutely required. Notably, despite differences in cell-free infectivity, the authentic variants of concern (VOCs) B.1.1.7 (alpha) and B.1.351 (beta) have similar cell-to-cell transmission capability. Moreover, B.1.351 is more resistant to neutralization by vaccinee sera in cell-free infection, whereas B.1.1.7 is more resistant to inhibition by vaccinee sera in cell-to-cell transmission. Overall, our study reveals critical features of SARS-CoV-2 spike-mediated cell-to-cell transmission, with important implications for a better understanding of SARS-CoV-2 spread and pathogenesis.


Subject(s)
COVID-19/immunology , COVID-19/transmission , SARS-CoV-2/immunology , Virus Internalization , Angiotensin-Converting Enzyme 2 , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral , COVID-19/therapy , Cell Fusion , Chlorocebus aethiops , HEK293 Cells , Humans , Immunization, Passive , Spike Glycoprotein, Coronavirus/immunology , Vero Cells
13.
Preprint in English | bioRxiv | ID: ppbiorxiv-472934

ABSTRACT

The SARS-CoV-2 B.1.1.529/Omicron variant was first characterized in South Africa and was swiftly designated a variant of concern1. Of great concern is its high number of mutations, including 30-40 mutations in the virus spike (S) protein compared to 7-10 for other variants. Some of these mutations have been shown to enhance escape from vaccine-induced immunity, while others remain uncharacterized. Additionally, reports of increasing frequencies of the Omicron variant may indicate a higher rate of transmission compared to other variants. However, the transmissibility of Omicron and its degree of resistance to vaccine-induced immunity remain unclear. Here we show that Omicron exhibits significant immune evasion compared to other variants, but antibody neutralization is largely restored by mRNA vaccine booster doses. Additionally, the Omicron spike exhibits reduced receptor binding, cell-cell fusion, S1 subunit shedding, but increased cell-to-cell transmission, and homology modeling indicates a more stable closed S structure. These findings suggest dual immune evasion strategies for Omicron, due to altered epitopes and reduced exposure of the S receptor binding domain, coupled with enhanced transmissibility due to enhanced S protein stability. These results highlight the importance of booster vaccine doses for maintaining protection against the Omicron variant, and provide mechanistic insight into the altered functionality of the Omicron spike protein.

14.
2021.
Preprint in English | Other preprints | ID: ppcovidwho-296266

ABSTRACT

5-Methylcytosine (m 5 C) is a widespread post-transcriptional RNA modification and is reported to be involved in manifold cellular responses and biological processes through regulating RNA metabolism. However, its regulatory role in antiviral innate immunity has not yet been elucidated. Here, we report that NSUN2, a typical m 5 C methyltransferase, can negatively regulate type I interferon responses during viral infection. NSUN2 specifically mediates m 5 C methylation of IRF3 mRNA and accelerates its degradation, resulting in low levels of IRF3 and downstream IFN-β production. Knockout or knockdown of NSUN2 could enhance type I interferon responses and downstream ISG expression after viral infection in vitro . And in vivo , the antiviral innate responses is more dramatically enhanced in Nsun2 +/− mice than in Nsun2 +/+ mice. Four highly m 5 C methylated cytosines in IRF3 mRNA were identified, and their mutation could enhance the cellular IRF3 mRNA levels. Moreover, infection with Sendai virus (SeV), vesicular stomatitis virus (VSV), herpes simplex virus 1 (HSV-1), Zika virus (ZIKV), or especially SARS-CoV-2 resulted in a reduction in endogenous levels of NSUN2. Together, our findings reveal that NSUN2 serves as a negative regulator of interferon response by accelerating the fast turnover of IRF3 mRNA, while endogenous NSUN2 levels decrease after viral infection to boost antiviral responses for the effective elimination of viruses. Our results suggest a paradigm of innate antiviral immune responses ingeniously involving NSUN2-mediated m 5 C modification.

15.
2021.
Preprint in English | Other preprints | ID: ppcovidwho-296045

ABSTRACT

ABSTRACT BACKGROUND SARS-CoV-2 causes COVID-19 through direct lysis of infected lung epithelial cells, which releases damage-associated molecular patterns (DAMPs) and induces a pro-inflammatory cytokine milieu causing systemic inflammation. Anti-viral and anti-inflammatory agents have shown limited therapeutic efficacy. Soluble CD24 (CD24Fc) is able to blunt the broad inflammatory response induced by DAMPs in multiple models. A recent randomized phase III trial evaluating the impact of CD24Fc in patients with severe COVID-19 demonstrated encouraging clinical efficacy. METHODS We studied peripheral blood samples obtained from patients enrolled at a single institution in the SAC-COVID trial ( NCT04317040 ) collected before and after treatment with CD24Fc or placebo. We performed high dimensional spectral flow cytometry analysis of peripheral blood mononuclear cells and measured the levels of a broad array of cytokines and chemokines. A systems analytical approach was used to discern the impact of CD24Fc treatment on immune homeostasis in patients with COVID-19. FINDINGS Twenty-two patients were enrolled, and the clinical characteristics from the CD24Fc vs. placebo groups were matched. Using high-content spectral flow cytometry and network-level analysis, we found systemic hyper-activation of multiple cellular compartments in the placebo group, including CD8 + T cells, CD4 + T cells, and CD56 + NK cells. By contrast, CD24Fc-treated patients demonstrated blunted systemic inflammation, with a return to homeostasis in both NK and T cells within days without compromising the ability of patients to mount an effective anti-Spike protein antibody response. A single dose of CD24Fc significantly attenuated induction of the systemic cytokine response, including expression of IL-10 and IL-15, and diminished the coexpression and network connectivity among extensive circulating inflammatory cytokines, the parameters associated with COVID-19 disease severity. INTERPRETATION Our data demonstrates that CD24Fc treatment rapidly down-modulates systemic inflammation and restores immune homeostasis in SARS-CoV-2-infected individuals, supporting further development of CD24Fc as a novel therapeutic against severe COVID-19. FUNDING NIH

16.
Cell Biosci ; 11(1): 197, 2021 Nov 21.
Article in English | MEDLINE | ID: covidwho-1528695

ABSTRACT

There is currently a critical need to determine the efficacy of SARS-CoV-2 vaccination for immunocompromised patients. In this study, we determined the neutralizing antibody response in 160 cancer patients diagnosed with chronic lymphocytic leukemia (CLL), lung cancer, breast cancer, and various non-Hodgkin's lymphomas (NHL), after they received two doses of mRNA vaccines. Serum from 46 mRNA vaccinated health care workers (HCWs) served as healthy controls. We discovered that (1) cancer patients exhibited reduced neutralizing antibody titer (NT50) compared to HCWs; (2) CLL and NHL patients exhibited the lowest NT50 levels, with 50-60% of them below the detection limit; (3) mean NT50 levels in patients with CLL and NHL was ~2.6 fold lower than those with solid tumors; and (4) cancer patients who received anti-B cell therapy exhibited significantly reduced NT50 levels. Our results demonstrate an urgent need for novel immunization strategies for cancer patients against SARS-CoV-2, particularly those with hematological cancers and those on anti-B cell therapies.

17.
[Unspecified Source]; 2020.
Preprint in English | [Unspecified Source] | ID: ppcovidwho-292812

ABSTRACT

Rapid and specific antibody testing is crucial for improved understanding, control, and treatment of COVID-19 pathogenesis. Herein, we describe and apply a rapid, sensitive, and accurate virus neutralization assay for SARS-CoV-2 antibodies. The new assay is based on an HIV-1 lentiviral vector that contains a secreted intron Gaussia luciferase or secreted Nano-luciferase reporter cassette, pseudotyped with the SARS-CoV-2 spike (S) glycoprotein, and is validated with a plaque reduction assay using an authentic, infectious SARS-CoV-2 strain. The new assay was used to evaluate SARS-CoV-2 antibodies in serum from individuals with a broad range of COVID-19 symptoms, including intensive care unit (ICU) patients, health care workers (HCWs), and convalescent plasma donors. The highest neutralizing antibody titers were observed among ICU patients, followed by general hospitalized patients, HCWs and convalescent plasma donors. Our study highlights a wide phenotypic variation in human antibody responses against SARS-CoV-2, and demonstrates the efficacy of a novel lentivirus pseudotype assay for high-throughput serological surveys of neutralizing antibody titers in large cohorts.

18.
mBio ; 12(5): e0251021, 2021 10 26.
Article in English | MEDLINE | ID: covidwho-1450587

ABSTRACT

The sensitivity of SARS-CoV-2 variants of concern (VOCs) to neutralizing antibodies has largely been studied in the context of key receptor binding domain (RBD) mutations, including E484K and N501Y. Little is known about the epistatic effects of combined SARS-CoV-2 spike mutations. We now investigate the neutralization sensitivity of variants containing the non-RBD mutation Q677H, including B.1.525 (Nigerian isolate) and Bluebird (U.S. isolate) variants. The effect on neutralization of Q677H was determined in the context of the RBD mutations and in the background of major VOCs, including B.1.1.7 (United Kingdom, Alpha), B.1.351 (South Africa, Beta), and P1-501Y-V3 (Brazil, Gamma). We demonstrate that the Q677H mutation increases viral infectivity and syncytium formation, as well as enhancing resistance to neutralization for VOCs, including B.1.1.7 and P1-501Y-V3. Our work highlights the importance of epistatic interactions between SARS-CoV-2 spike mutations and the continued need to monitor Q677H-bearing VOCs. IMPORTANCE SARS-CoV-2, the causative agent of COVID-19, is rapidly evolving to be more transmissible and to evade acquired immunity. To date, most investigations of SARS-CoV-2 variants have focused on RBD mutations. However, the impact of non-RBD mutations and their synergy with studied RBD mutations are poorly understood. Here, we examine the role of the non-RBD Q677H mutation arising in many SARS-CoV-2 lineages, including VOCs. We demonstrate that the Q677H mutation enhances viral infectivity and confers neutralizing antibody resistance, particularly in the background of other SARS-CoV-2 VOCs.


Subject(s)
Antibodies, Neutralizing/metabolism , COVID-19/metabolism , SARS-CoV-2/pathogenicity , Spike Glycoprotein, Coronavirus/immunology , Antibodies, Viral/metabolism , HEK293 Cells , Humans , Mutation , Protein Binding , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/metabolism
19.
J Virol ; 95(20): e0059221, 2021 09 27.
Article in English | MEDLINE | ID: covidwho-1440799

ABSTRACT

The current pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to dramatic economic and health burdens. Although the worldwide SARS-CoV-2 vaccination campaign has begun, exploration of other vaccine candidates is needed due to uncertainties with the current approved vaccines, such as durability of protection, cross-protection against variant strains, and costs of long-term production and storage. In this study, we developed a methyltransferase-defective recombinant vesicular stomatitis virus (mtdVSV)-based SARS-CoV-2 vaccine candidate. We generated mtdVSVs expressing SARS-CoV-2 full-length spike (S) protein, S1, or its receptor-binding domain (RBD). All of these recombinant viruses grew to high titers in mammalian cells despite high attenuation in cell culture. The SARS-CoV-2 S protein and its truncations were highly expressed by the mtdVSV vector. These mtdVSV-based vaccine candidates were completely attenuated in both immunocompetent and immunocompromised mice. Among these constructs, mtdVSV-S induced high levels of SARS-CoV-2-specific neutralizing antibodies (NAbs) and Th1-biased T-cell immune responses in mice. In Syrian golden hamsters, the serum levels of SARS-CoV-2-specific NAbs triggered by mtdVSV-S were higher than the levels of NAbs in convalescent plasma from recovered COVID-19 patients. In addition, hamsters immunized with mtdVSV-S were completely protected against SARS-CoV-2 replication in lung and nasal turbinate tissues, cytokine storm, and lung pathology. Collectively, our data demonstrate that mtdVSV expressing SARS-CoV-2 S protein is a safe and highly efficacious vaccine candidate against SARS-CoV-2 infection. IMPORTANCE Viral mRNA cap methyltransferase (MTase) is essential for mRNA stability, protein translation, and innate immune evasion. Thus, viral mRNA cap MTase activity is an excellent target for development of live attenuated or live vectored vaccine candidates. Here, we developed a panel of MTase-defective recombinant vesicular stomatitis virus (mtdVSV)-based SARS-CoV-2 vaccine candidates expressing full-length S, S1, or several versions of the RBD. These mtdVSV-based vaccine candidates grew to high titers in cell culture and were completely attenuated in both immunocompetent and immunocompromised mice. Among these vaccine candidates, mtdVSV-S induces high levels of SARS-CoV-2-specific neutralizing antibodies (Nabs) and Th1-biased immune responses in mice. Syrian golden hamsters immunized with mtdVSV-S triggered SARS-CoV-2-specific NAbs at higher levels than those in convalescent plasma from recovered COVID-19 patients. Furthermore, hamsters immunized with mtdVSV-S were completely protected against SARS-CoV-2 challenge. Thus, mtdVSV is a safe and highly effective vector to deliver SARS-CoV-2 vaccine.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19/prevention & control , SARS-CoV-2/immunology , Vesicular stomatitis Indiana virus/genetics , Animals , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , Brain/virology , COVID-19/immunology , Cell Line , Cytokine Release Syndrome/prevention & control , DNA-Directed RNA Polymerases/genetics , DNA-Directed RNA Polymerases/metabolism , Humans , Immunogenicity, Vaccine , Lung/immunology , Lung/pathology , Lung/virology , Mesocricetus , Methyltransferases/genetics , Methyltransferases/metabolism , Mice , Protein Domains , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Th1 Cells/immunology , Vaccines, Synthetic/immunology , Vesicular stomatitis Indiana virus/enzymology , Vesicular stomatitis Indiana virus/physiology , Viral Proteins/genetics , Viral Proteins/metabolism , Virus Replication
20.
Proc Natl Acad Sci U S A ; 118(34)2021 08 24.
Article in English | MEDLINE | ID: covidwho-1345645

ABSTRACT

Alum, used as an adjuvant in injected vaccines, promotes T helper 2 (Th2) and serum antibody (Ab) responses. However, it fails to induce secretory immunoglobulin (Ig) A (SIgA) in mucosal tissues and is poor in inducing Th1 and cell-mediated immunity. Alum stimulates interleukin 1 (IL-1) and the recruitment of myeloid cells, including neutrophils. We investigated whether neutrophil elastase regulates the adjuvanticity of alum, and whether a strategy targeting neutrophil elastase could improve responses to injected vaccines. Mice coadministered a pharmacological inhibitor of elastase, or lacking elastase, developed high-affinity serum IgG and IgA antibodies after immunization with alum-adsorbed protein vaccines, including the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2). These mice also developed broader antigen-specific CD4+ T cell responses, including high Th1 and T follicular helper (Tfh) responses. Interestingly, in the absence of elastase activity, mucosal SIgA responses were induced after systemic immunization with alum as adjuvant. Importantly, lack or suppression of elastase activity enhanced the magnitude of anti-SARS-CoV-2 spike subunit 1 (S1) antibodies, and these antibodies reacted with the same epitopes of spike 1 protein as sera from COVID-19 patients. Therefore, suppression of neutrophil elastase could represent an attractive strategy for improving the efficacy of alum-based injected vaccines for the induction of broad immunity, including mucosal immunity.


Subject(s)
Adjuvants, Immunologic/pharmacology , Alum Compounds/pharmacology , COVID-19/immunology , COVID-19/therapy , Enzyme Inhibitors/pharmacology , Leukocyte Elastase/antagonists & inhibitors , SARS-CoV-2/immunology , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Antibody Formation/drug effects , COVID-19/drug therapy , COVID-19/metabolism , HEK293 Cells , Humans , Immunity, Innate/drug effects , Immunity, Innate/immunology , Immunity, Mucosal/drug effects , Immunity, Mucosal/immunology , Immunoglobulin A/immunology , Leukocyte Elastase/metabolism , Mice , Mice, Inbred C57BL , Mice, Knockout , SARS-CoV-2/drug effects , Spike Glycoprotein, Coronavirus/immunology , Swine , Th1 Cells/immunology
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