Intradermal Immunization of SARS-CoV-2 Original Strain Trimeric Spike Protein Associated to CpG and AddaS03 Adjuvants, but Not MPL, Provide Strong Humoral and Cellular Response in Mice (original) (raw)
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SARS CoV subunit vaccine: antibody-mediated neutralisation and enhancement
Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine, 2012
1. A SARS vaccine was produced based on recombinant native full-length Spike-protein trimers (triSpike) and efficient establishment of a vaccination procedure in rodents. 2. Antibody-mediated enhancement of SARS-CoV infection with anti-SARS-CoV Spike immune-serum was observed in vitro. 3. Antibody-mediated infection of SARS-CoV triggers entry into human haematopoietic cells via an FcγR-dependent and ACE2-, pH-, cysteine-protease-independent pathways. 4. The antibody-mediated enhancement phenomenon is not a mandatory component of the humoral immune response elicited by SARS vaccines, as pure neutralising antibody only could be obtained. 5. Occurrence of immune-mediated enhancement of SARS-CoV infection raises safety concerns regarding the use of SARS-CoV vaccine in humans and enables new ways to investigate SARS pathogenesis (tropism and immune response deregulation).
2021
Several inactivated SARS-CoV-2 vaccines were approved for human use but are not highly potent. Here, different formulations of inactivated SARS-CoV-2 virus in Alum, Montanide 51VG and Montanide ISA720VG adjuvants were developed and then immune responses were assessed. SARS-CoV-2 virus was inactivated with formalin and formulated in the adjuvants. BALB/c mice were immunized subcutaneously with 4µg of experimental vaccines on days 0 and 14 and two weeks after the final immunization, IL-4 and IFN-γ cytokines, CTL activity and specific IgG titer and IgG1, IgG2a, IgG2a/IgG1 ratio and also anti-RBD IgG response were assessed. Immunization with SARS-CoV-2-Montanide ISA51VG showed a significant increase in IFN-γ cytokine versus SARS-CoV-2-Alum, SARS-CoV-2-Montanide ISA720VG and control groups (P<0.0033). Cytokine IL-4 response in SARS-CoV-2-Alum group showed a significant increase versus SARS-CoV-2-Montanide ISA51VG, SARS-CoV-2-Montanide ISA720VG and control groups (P<0.0206). In addi...
Scientific Reports
With the persistence of the SARS-CoV-2 pandemic and the emergence of novel variants, the development of novel vaccine formulations with enhanced immunogenicity profiles could help reduce disease burden in the future. Intranasally delivered vaccines offer a new modality to prevent SARS-CoV-2 infections through the induction of protective immune responses at the mucosal surface where viral entry occurs. Herein, we evaluated a novel protein subunit vaccine formulation containing a resistin-trimerized prefusion Spike antigen (SmT1v3) and a proteosome-based mucosal adjuvant (BDX301) formulated to enable intranasal immunization. In mice, the formulation induced robust antigen-specific IgG and IgA titers, in the blood and lungs, respectively. In addition, the formulations were highly efficacious in a hamster challenge model, reducing viral load and body weight loss. In both models, the serum antibodies had strong neutralizing activity, preventing the cellular binding of the viral Spike pro...
2022
With the persistence of the SARS-CoV-2 pandemic and the emergence of novel variants, the development of novel vaccine formulations with enhanced immunogenicity profiles could help reduce disease burden in the future. Intranasally delivered vaccines offer a new modality to prevent SARS-CoV-2 infections through the induction of protective immune responses at the mucosal surface where viral entry occurs. Herein, we evaluated a novel protein subunit vaccine formulation containing a resistin-trimerized prefusion Spike antigen (SmT1v3) and a proteosome-based mucosal adjuvant (BDX301) formulated to enable intranasal immunization. In mice, the formulation induced robust antigen-specific IgG and IgA titers, in the blood and lungs, respectively. In addition, the formulations were highly efficacious in a hamster challenge model, reducing viral load and body weight loss. In both models, the serum antibodies had strong neutralizing activity, preventing the cellular binding of the viral Spike pro...
Phase 1–2 Trial of a SARS-CoV-2 Recombinant Spike Protein Nanoparticle Vaccine
New England Journal of Medicine
BACKGROUND NVX-CoV2373 is a recombinant severe acute respiratory syndrome coronavirus 2 (rSARS-CoV-2) nanoparticle vaccine composed of trimeric full-length SARS-CoV-2 spike glycoproteins and Matrix-M1 adjuvant. METHODS We initiated a randomized, placebo-controlled, phase 1-2 trial to evaluate the safety and immunogenicity of the rSARS-CoV-2 vaccine (in 5-μg and 25-μg doses, with or without Matrix-M1 adjuvant, and with observers unaware of trial-group assignments) in 131 healthy adults. In phase 1, vaccination comprised two intramuscular injections, 21 days apart. The primary outcomes were reactogenicity; laboratory values (serum chemistry and hematology), according to Food and Drug Administration toxicity scoring, to assess safety; and IgG anti-spike protein response (in enzyme-linked immunosorbent assay [ELISA] units). Secondary outcomes included unsolicited adverse events, wild-type virus neutralization (microneutralization assay), and T-cell responses (cytokine staining). IgG and microneutralization assay results were compared with 32 (IgG) and 29 (neutralization) convalescent serum samples from patients with Covid-19, most of whom were symptomatic. We performed a primary analysis at day 35. RESULTS After randomization, 83 participants were assigned to receive the vaccine with adjuvant and 25 without adjuvant, and 23 participants were assigned to receive placebo. No serious adverse events were noted. Reactogenicity was absent or mild in the majority of participants, more common with adjuvant, and of short duration (mean, ≤2 days). One participant had mild fever that lasted 1 day. Unsolicited adverse events were mild in most participants; there were no severe adverse events. The addition of adjuvant resulted in enhanced immune responses, was antigen dosesparing, and induced a T helper 1 (Th1) response. The two-dose 5-μg adjuvanted regimen induced geometric mean anti-spike IgG (63,160 ELISA units) and neutralization (3906) responses that exceeded geometric mean responses in convalescent serum from mostly symptomatic Covid-19 patients (8344 and 983, respectively). CONCLUSIONS At 35 days, NVX-CoV2373 appeared to be safe, and it elicited immune responses that exceeded levels in Covid-19 convalescent serum. The Matrix-M1 adjuvant induced CD4+ T-cell responses that were biased toward a Th1 phenotype. (Funded by the Coalition for Epidemic Preparedness Innovations; ClinicalTrials.gov number, NCT04368988).
First-in-Human Trial of a SARS CoV 2 Recombinant Spike Protein Nanoparticle Vaccine
Background NVX-CoV2373 is a recombinant nanoparticle vaccine composed of trimeric full-length SARS-CoV-2 spike glycoproteins. We present the Day 35 primary analysis of our trial of NVX-CoV2373 with or without the saponin-based Matrix-M1 adjuvant in healthy adults. Methods This is a randomized, observer-blinded, placebo-controlled, phase 1 trial in 131 healthy adults. Trial vaccination comprised two intramuscular injections, 21 days apart. Primary outcomes were reactogenicity, safety labs, and immunoglobulin G (IgG) anti-spike protein response. Secondary outcomes included adverse events, wild-type virus neutralizing antibody, and T-cell responses. Results Participants received NVX-CoV2373 with or without Matrix-M1 (n=106) or placebo (n=25). There were no serious adverse events. Reactogenicity was mainly mild in severity and of short duration (mean ≥ 2 days), with second vaccinations inducing greater local and systemic reactogenicity. The adjuvant significantly enhanced immune respons...
Viruses, 2022
The global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become more serious because of the continuous emergence of variants of concern (VOC), thus calling for the development of broad-spectrum vaccines with greater efficacy. Adjuvants play important roles in enhancing the immunogenicity of protein-based subunit vaccines. In this study, we compared the effect of three adjuvants, including aluminum, nanoparticle manganese and MF59, on the immunogenicity of three protein-based COVID-19 vaccine candidates, including RBD-Fc, RBD and S-trimer. We found that the nanoparticle manganese adjuvant elicited the highest titers of SARS-CoV-2 RBD-specific IgG, IgG1 and IgG2a, as well as neutralizing antibodies against infection by pseudotyped SARS-CoV-2 and its Delta variant. What is more, the nanoparticle manganese adjuvant effectively reduced the viral load of the authentic SARS-CoV-2 and Delta variant in the cell cult...
Efficacy of the Vaccines, Their Safety, and Immune Responses against SARS-CoV-2 Infections
The search for vaccines has been a high priority since the worldwide COVID-19 pandemic was declared. Currently, mRNA-based vaccines, adenovirus-based vaccines, inactivated virus vaccines, and other vaccine platforms are all employed to combat the SARS-CoV-2 virus. BNT162b2 and mRNA-1273 are mRNA-based vaccines. The vaccination appears to be effective against SARS-CoV-2 strains that have emerged since the first study. They have primarily minor side effects, and there are no major safety concerns. Adenovirus-based vaccines are delivered by genetic cargo that is based on non-replicating adenovirus vectors that can increase immune response without the need of adjuvants. This is the case for Ad26.CoV2.S, ChAdOx1 nCoV-19/AZD1222, Gam-COVID-Vac/Sputnik V andAd5-based COVID-19 vaccine. There have been no known incidences of allergy to adenovirus vaccines, unlike mRNA vaccines. Inactivated virus vaccines are a common form of vaccine that has been used for decades. The goal is to render the virus non-infectious while preserving immunogenicity with high-quality antigens in order to trigger an immune response. The researched formaldehyde-inactivated whole-virus SARS-CoV2 vaccine (CoronaVac), as well as WIV04 and HB02, utilize this sort of vaccine formulation. A recombinant protein nanoparticle vaccine named NVX-CoV2373 is made up of trimeric spike glycoproteins with a potent Matrix-M1 adjuvant. Against the variant B.1.1.7 (Alpha), the vaccine appeared to be very effective. Vaccine efficacy against the B.1.351 (Beta) strain, on the other hand, proved to be lower.
Establishment of an mRNA vaccine platform in low- and middle-income countries (LMICs) is important to enhance vaccine accessibility and ensure future pandemic preparedness. Here, we describe the preclinical studies of a SARS-CoV-2 mRNA encoding prefusion-unstabilized ectodomain spike protein encapsulated in lipid nanoparticles (LNP) “ChulaCov19”. In BALB/c mice, ChulaCov19 at 0.2, 1, 10, and 30 μg given 2 doses, 21 days apart, elicited robust neutralizing antibody (NAb) and T cells responses in a dose-dependent relationship. The geometric mean titer (GMT) of micro-virus neutralizing (micro-VNT) antibody against wild-type virus was 1,280, 11,762, 54,047, and 62,084, respectively. Higher doses induced better cross-neutralizing antibody against Delta and Omicron variants. This elicited specific immunogenicity was significantly higher than those induced by homologous prime-boost with inactivated (CoronaVac) or viral vector (AZD1222) vaccine. In heterologous prime-boost study, mice prime...
Cellular and Humoral Immunogenicity of a Candidate DNA Vaccine Expressing SARS-CoV-2 Spike Subunit 1
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The urgent need for effective, safe and equitably accessible vaccines to tackle the ongoing spread of COVID-19 led researchers to generate vaccine candidates targeting varieties of immunogens of SARS-CoV-2. Because of its crucial role in mediating binding and entry to host cell and its proven safety profile, the subunit 1 (S1) of the spike protein represents an attractive immunogen for vaccine development. Here, we developed and assessed the immunogenicity of a DNA vaccine encoding the SARS-CoV-2 S1. Following in vitro confirmation and characterization, the humoral and cellular immune responses of our vaccine candidate (pVAX-S1) was evaluated in BALB/c mice using two different doses, 25 µg and 50 µg. Our data showed high levels of SARS-CoV-2 specific IgG and neutralizing antibodies in mice immunized with three doses of pVAX-S1. Analysis of the induced IgG subclasses showed a Th1-polarized immune response, as demonstrated by the significant elevation of spike-specific IgG2a and IgG2b...