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1.
J Virol ; 96(17): e0011822, 2022 09 14.
Article in English | MEDLINE | ID: covidwho-1992935

ABSTRACT

SARS-CoV-2 has mutated frequently since its first emergence in 2019. Numerous variants, including the currently emerging Omicron variant, have demonstrated high transmissibility or increased disease severity, posing serious threats to global public health. This study describes the identification of an immunodominant non-neutralizing epitope on SARS-CoV-2 receptor-binding domain (RBD). A subunit vaccine against this mutant RBD, constructed by masking this epitope with a glycan probe, did not significantly affect RBD's receptor-binding affinity or antibody-binding affinity, or its ability to induce antibody production. However, this vaccine enhanced the neutralizing activity of this RBD and its protective efficacy in immunized mice. Specifically, this vaccine elicited significantly higher-titer neutralizing antibodies than the prototypic RBD protein against Alpha (B.1.1.7 lineage), Beta (B.1.351 lineage), Gamma (P.1 lineage), and Epsilon (B.1.427 or B.1.429 lineage) variant pseudoviruses containing single or combined mutations in the spike (S) protein, albeit the neutralizing antibody titers against some variants were slightly lower than against original SARS-CoV-2. This vaccine also significantly improved the neutralizing activity of the prototypic RBD against pseudotyped and authentic Delta (B.1.617.2 lineage) and Omicron (B.1.1.529 lineage) variants, although the neutralizing antibody titers were lower than against original SARS-CoV-2. In contrast to the prototypic RBD, the mutant RBD completely protected human ACE2 (hACE2)-transgenic mice from lethal challenge with a prototype SARS-CoV-2 strain and a Delta variant without weight loss. Overall, these findings indicate that this RBD vaccine has broad-spectrum activity against multiple SARS-CoV-2 variants, as well as the potential to be effective and have improved efficacy against Omicron and other pandemic variants. IMPORTANCE Several SARS-CoV-2 variants have shown increased transmissibility, calling for a need to develop effective vaccines with broadly neutralizing activity against multiple variants. This study identified a non-neutralizing epitope on the receptor-binding domain (RBD) of SARS-CoV-2 spike protein, and further shielded it with a glycan probe. A subunit vaccine based on this mutant RBD significantly enhanced the ability of prototypic RBD against multiple SARS-CoV-2 variants, including the Delta and Omicron strains, although the neutralizing antibody titers against some of these variants were lower than those against original SARS-CoV-2. This mutant vaccine also enhanced the protective efficacy of the prototypic RBD vaccine against SARS-CoV-2 infection in immunized animals. In conclusion, this study identified an engineered RBD vaccine against Omicron and other SARS-CoV-2 variants that induced stronger neutralizing antibodies and protection than the original RBD vaccine. It also highlights the need to improve the effectiveness of current COVID-19 vaccines to prevent pandemic SARS-CoV-2 variants.


Subject(s)
Antibodies, Neutralizing , Antibodies, Viral , COVID-19 Vaccines , COVID-19 , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/prevention & control , COVID-19 Vaccines/immunology , Epitopes , Glycosylation , Humans , Mice , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/chemistry , Vaccines, Subunit/immunology
2.
Cell Rep ; 36(8): 109591, 2021 08 24.
Article in English | MEDLINE | ID: covidwho-1370154

ABSTRACT

The relationship between B cells and CD4 T cells has been carefully studied, revealing a collaborative effort in which B cells promote the activation, differentiation, and expansion of CD4 T cells while the so-called "helper" cells provide signals to B cells, influencing their class switching and fate. Interactions between B cells and CD8 T cells are not as well studied, although CD8 T cells exhibit an accelerated contraction after certain infections in B-cell-deficient mice. Here, we find that B cells significantly enhance primary CD8 T cell responses after vaccination. Moreover, memory CD8 numbers and function are impaired in B-cell-deficient animals, leading to increased susceptibility to bacterial challenge. We also show that interleukin-27 production by B cells contributes to their impact on primary, but not memory, CD8 responses. Better understanding of the interactions between CD8 T cells and B cells may aid in the design of more effective future vaccine strategies.


Subject(s)
B-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , Immunologic Memory , Interleukin-27/immunology , Interleukin-27/metabolism , T-Lymphocytes, Helper-Inducer/immunology , Vaccines, Subunit/immunology , Animals , B-Lymphocytes/metabolism , CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/metabolism , COVID-19/immunology , Humans , Lymphocyte Count , Mice , Mice, Inbred C57BL , Receptors, Virus/immunology , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Vaccination
3.
Biosci Rep ; 41(9)2021 09 30.
Article in English | MEDLINE | ID: covidwho-1915305

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the global pandemic of the Coronavirus disease in late 2019 (COVID-19). Vaccine development efforts have predominantly been aimed at 'Extra-viral' Spike (S) protein as vaccine vehicles, but there are concerns regarding 'viral immune escape' since multiple mutations may enable the mutated virus strains to escape from immunity against S protein. The 'Intra-viral' Nucleocapsid (N-protein) is relatively conserved among mutant strains of coronaviruses during spread and evolution. Herein, we demonstrate novel vaccine candidates against SARS-CoV-2 by using the whole conserved N-protein or its fragment/peptides. Using ELISA assay, we showed that high titers of specific anti-N antibodies (IgG, IgG1, IgG2a, IgM) were maintained for a reasonably long duration (> 5 months), suggesting that N-protein is an excellent immunogen to stimulate host immune system and robust B-cell activation. We synthesized three peptides located at the conserved regions of N-protein among CoVs. One peptide showed as a good immunogen for vaccination as well. Cytokine arrays on post-vaccination mouse sera showed progressive up-regulation of various cytokines such as IFN-γ and CCL5, suggesting that TH1 associated responses are also stimulated. Furthermore, vaccinated mice exhibited an elevated memory T cells population. Here, we propose an unconventional vaccine strategy targeting the conserved N-protein as an alternative vaccine target for coronaviruses. Moreover, we generated a mouse monoclonal antibody specifically against an epitope shared between SARS-CoV and SARS-CoV-2, and we are currently developing the First-in-Class humanized anti-N-protein antibody to potentially treat patients infected by various CoVs in the future.


Subject(s)
Antibodies, Viral/blood , COVID-19 Vaccines/immunology , COVID-19/prevention & control , Coronavirus Nucleocapsid Proteins/immunology , Animals , Antibodies, Monoclonal, Murine-Derived , Antibodies, Viral/immunology , COVID-19/immunology , COVID-19/virology , COVID-19 Vaccines/administration & dosage , COVID-19 Vaccines/genetics , Coronavirus Nucleocapsid Proteins/genetics , Epitopes/immunology , Humans , Immune Evasion , Immunogenicity, Vaccine , Mice , Models, Animal , Pandemics/prevention & control , SARS Virus/genetics , SARS Virus/immunology , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Sequence Homology, Amino Acid , Spike Glycoprotein, Coronavirus/immunology , Th1 Cells/immunology , Vaccines, Subunit/administration & dosage , Vaccines, Subunit/genetics , Vaccines, Subunit/immunology
4.
Viruses ; 14(5)2022 04 21.
Article in English | MEDLINE | ID: covidwho-1879492

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), especially emerging variants, poses an increased threat to global public health. The significant reduction in neutralization activity against the variants such as B.1.351 in the serum of convalescent patients and vaccinated people calls for the design of new potent vaccines targeting the emerging variant. However, since most vaccines approved and in clinical trials are based on the sequence of the original SARS-CoV-2 strain, the immunogenicity and protective efficacy of vaccines based on the B.1.351 variant remain largely unknown. In this study, we evaluated the immunogenicity, induced neutralization activity, and protective efficacy of wild-type spike protein nanoparticle (S-2P) and mutant spike protein nanoparticle (S-4M-2P) carrying characteristic mutations of B.1.351 variant in mice. Although there was no significant difference in the induction of spike-specific IgG responses in S-2P- and S-4M-2P-immunized mice, neutralizing antibodies elicited by S-4M-2P exhibited noteworthy, narrower breadth of reactivity with SARS-CoV-2 variants compared with neutralizing antibodies elicited by S-2P. Furthermore, the decrease of induced neutralizing antibody breadth at least partly resulted from the amino acid substitution at position 484. Moreover, S-4M-2P vaccination conferred insufficient protection against live SARS-CoV-2 virus infection, while S-2P vaccination gave definite protection against SARS-CoV-2 challenge in mice. Together, our study provides direct evidence that the E484K substitution in a SARS-CoV-2 subunit protein vaccine limited the cross-reactive neutralizing antibody breadth in mice and, more importantly, draws attention to the unfavorable impact of this mutation in spike protein of SARS-CoV-2 variants on the induction of potent neutralizing antibody responses.


Subject(s)
Antibodies, Neutralizing , COVID-19 Vaccines , COVID-19 , Cross Reactions , Spike Glycoprotein, Coronavirus , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/prevention & control , COVID-19 Vaccines/genetics , COVID-19 Vaccines/immunology , Mice , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics , Vaccines, Subunit/genetics , Vaccines, Subunit/immunology
5.
Viruses ; 14(5)2022 05 16.
Article in English | MEDLINE | ID: covidwho-1855825

ABSTRACT

Currently, SARS-CoV-2 spike receptor-binding-domain (RBD)-based vaccines are considered one of the most effective weapons against COVID-19. During the first step of assessing vaccine immunogenicity, a mouse model is often used. In this paper, we tested the use of five experimental animals (mice, hamsters, rabbits, ferrets, and chickens) for RBD immunogenicity assessments. The humoral immune response was evaluated by ELISA and virus-neutralization assays. The data obtained show hamsters to be the least suitable candidates for RBD immunogenicity testing and, hence, assessing the protective efficacy of RBD-based vaccines.


Subject(s)
COVID-19 Vaccines , COVID-19 , Immunogenicity, Vaccine , Spike Glycoprotein, Coronavirus , Animals , COVID-19/prevention & control , COVID-19 Vaccines/immunology , Chickens , Cricetinae , Disease Models, Animal , Ferrets , Mice , Mice, Inbred BALB C , Rabbits , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/immunology , Vaccines, Subunit/immunology
6.
J Med Chem ; 65(4): 3563-3574, 2022 02 24.
Article in English | MEDLINE | ID: covidwho-1671476

ABSTRACT

Safe and effective vaccines are the best method to defeat worldwide SARS-CoV-2 and its circulating variants. The SARS-CoV-2 S protein and its subunits are the most attractive targets for the development of protein-based vaccines. In this study, we evaluated three lipophilic adjuvants, monophosphoryl lipid A (MPLA), Toll-like receptor (TLR) 1/2 ligand Pam3CSK4, and α-galactosylceramide (α-GalCer), in liposomal and nonliposomal vaccines. The immunological results showed that the MPLA-adjuvanted liposomal vaccine induced the strongest humoral and cellular immunity. Therefore, we further performed a systematic comparison of S-trimer, S-ECD, S1, and RBD as antigens in MPLA-adjuvanted liposomes and found that, although these four vaccines all induced robust specific antibody responses, only S-trimer, S1, and RBD liposomes, but not S-ECD, elicited potent neutralizing antibody responses. Moreover, RBD, S-trimer, and S1 liposomes effectively neutralized variants (B.1.1.7/alpha, B.1.351/beta, P.1/gamma, B.1.617.2/delta, and B.1.1.529/omicron). These results provide important information for the subunit vaccine design against SARS-CoV-2 and its variants.


Subject(s)
Antibodies, Viral/immunology , Lipid A/analogs & derivatives , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Vaccines, Subunit/immunology , Adjuvants, Immunologic , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/chemistry , Female , Lipid A/chemistry , Lipid A/immunology , Liposomes/immunology , Mice , Mice, Inbred BALB C , Molecular Structure , Vaccination , Vaccines, Subunit/chemistry
7.
Cell Rep ; 38(8): 110399, 2022 02 22.
Article in English | MEDLINE | ID: covidwho-1664737

ABSTRACT

Follicular helper T (Tfh) cells promote, whereas follicular regulatory T (Tfr) cells restrain, germinal center (GC) reactions. However, the precise roles of these cells in the complex GC reaction remain poorly understood. Here, we perturb Tfh or Tfr cells after SARS-CoV-2 spike protein vaccination in mice. We find that Tfh cells promote the frequency and somatic hypermutation (SHM) of Spike-specific GC B cells and regulate clonal diversity. Tfr cells similarly control SHM and clonal diversity in the GC but do so by limiting clonal competition. In addition, deletion of Tfh or Tfr cells during primary vaccination results in changes in SHM after vaccine boosting. Aged mice, which have altered Tfh and Tfr cells, have lower GC responses, presenting a bimodal distribution of SHM. Together, these data demonstrate that GC responses to SARS-CoV-2 spike protein vaccines require a fine balance of positive and negative follicular T cell help to optimize humoral immunity.


Subject(s)
COVID-19/prevention & control , Germinal Center/immunology , Spike Glycoprotein, Coronavirus/administration & dosage , T-Lymphocytes, Helper-Inducer/immunology , T-Lymphocytes, Regulatory/immunology , Aging , Animals , Antibodies, Viral/blood , B-Lymphocytes/immunology , B-Lymphocytes/metabolism , COVID-19/virology , Germinal Center/cytology , Germinal Center/metabolism , Immunity, Humoral , Mice , Mice, Inbred C57BL , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/immunology , T-Lymphocytes, Helper-Inducer/cytology , T-Lymphocytes, Helper-Inducer/metabolism , T-Lymphocytes, Regulatory/cytology , T-Lymphocytes, Regulatory/metabolism , Vaccination , Vaccines, Subunit/immunology
8.
J Immunol Methods ; 502: 113216, 2022 03.
Article in English | MEDLINE | ID: covidwho-1611844

ABSTRACT

Coronavirus Disease 2019 (COVID-19) represents a new global threat demanding a multidisciplinary effort to fight its etiological agent-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this regard, immunoinformatics may aid to predict prominent immunogenic regions from critical SARS-CoV-2 structural proteins, such as the spike (S) glycoprotein, for their use in prophylactic or therapeutic interventions against this highly pathogenic betacoronavirus. Accordingly, in this study, an integrated immunoinformatics approach was applied to identify cytotoxic T cell (CTC), T helper cell (THC), and Linear B cell (BC) epitopes from the S glycoprotein in an attempt to design a high-quality multi-epitope vaccine. The best CTC, THC, and BC epitopes showed high viral antigenicity and lack of allergenic or toxic residues, as well as CTC and THC epitopes showed suitable interactions with HLA class I (HLA-I) and HLA class II (HLA-II) molecules, respectively. Remarkably, SARS-CoV-2 receptor-binding domain (RBD) and its receptor-binding motif (RBM) harbour several potential epitopes. The structure prediction, refinement, and validation data indicate that the multi-epitope vaccine has an appropriate conformation and stability. Four conformational epitopes and an efficient binding between Toll-like receptor 4 (TLR4) and the vaccine model were observed. Importantly, the population coverage analysis showed that the multi-epitope vaccine could be used globally. Notably, computer-based simulations suggest that the vaccine model has a robust potential to evoke and maximize both immune effector responses and immunological memory to SARS-CoV-2. Further research is needed to accomplish with the mandatory international guidelines for human vaccine formulations.


Subject(s)
Antigens, Viral/immunology , COVID-19 Vaccines/immunology , COVID-19/prevention & control , Spike Glycoprotein, Coronavirus/immunology , Amino Acid Sequence , Antigens, Viral/genetics , Antigens, Viral/metabolism , COVID-19/immunology , COVID-19/virology , COVID-19 Vaccines/genetics , COVID-19 Vaccines/therapeutic use , Computational Biology , Computer Simulation , Epitopes, B-Lymphocyte/genetics , Epitopes, B-Lymphocyte/immunology , Epitopes, T-Lymphocyte/genetics , Epitopes, T-Lymphocyte/immunology , Humans , Immunogenicity, Vaccine/genetics , Immunologic Memory , Protein Domains/genetics , Protein Domains/immunology , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism , T-Lymphocytes, Cytotoxic , Toll-Like Receptor 4/metabolism , Vaccines, Subunit/genetics , Vaccines, Subunit/immunology , Vaccines, Subunit/therapeutic use
9.
Front Immunol ; 12: 781280, 2021.
Article in English | MEDLINE | ID: covidwho-1608387

ABSTRACT

The development of more effective, accessible, and easy to administer COVID-19 vaccines next to the currently marketed mRNA, viral vector, and whole inactivated virus vaccines is essential to curtailing the SARS-CoV-2 pandemic. A major concern is reduced vaccine-induced immune protection to emerging variants, and therefore booster vaccinations to broaden and strengthen the immune response might be required. Currently, all registered COVID-19 vaccines and the majority of COVID-19 vaccines in development are intramuscularly administered, targeting the induction of systemic immunity. Intranasal vaccines have the capacity to induce local mucosal immunity as well, thereby targeting the primary route of viral entry of SARS-CoV-2 with the potential of blocking transmission. Furthermore, intranasal vaccines offer greater practicality in terms of cost and ease of administration. Currently, only eight out of 112 vaccines in clinical development are administered intranasally. We developed an intranasal COVID-19 subunit vaccine, based on a recombinant, six-proline-stabilized, D614G spike protein (mC-Spike) of SARS-CoV-2 linked via the LPS-binding peptide sequence mCramp (mC) to outer membrane vesicles (OMVs) from Neisseria meningitidis. The spike protein was produced in CHO cells, and after linking to the OMVs, the OMV-mC-Spike vaccine was administered to mice and Syrian hamsters via intranasal or intramuscular prime-boost vaccinations. In all animals that received OMV-mC-Spike, serum-neutralizing antibodies were induced upon vaccination. Importantly, high levels of spike-binding immunoglobulin G (IgG) and A (IgA) antibodies in the nose and lungs were only detected in intranasally vaccinated animals, whereas intramuscular vaccination only induced an IgG response in the serum. Two weeks after their second vaccination, hamsters challenged with SARS-CoV-2 were protected from weight loss and viral replication in the lungs compared to the control groups vaccinated with OMV or spike alone. Histopathology showed no lesions in lungs 7 days after challenge in OMV-mC-Spike-vaccinated hamsters, whereas the control groups did show pathological lesions in the lung. The OMV-mC-Spike candidate vaccine data are very promising and support further development of this novel non-replicating, needle-free, subunit vaccine concept for clinical testing.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19/immunology , Immunity, Mucosal/immunology , SARS-CoV-2/immunology , Administration, Intranasal , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/epidemiology , COVID-19/virology , COVID-19 Vaccines/administration & dosage , Cytoplasmic Vesicles/immunology , Female , Humans , Immunoglobulin A/immunology , Mesocricetus , Mice, Inbred BALB C , Neisseria meningitidis/immunology , Pandemics/prevention & control , SARS-CoV-2/metabolism , SARS-CoV-2/physiology , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism , Vaccination/methods , Vaccines, Subunit/administration & dosage , Vaccines, Subunit/immunology
10.
Brief Bioinform ; 23(1)2022 01 17.
Article in English | MEDLINE | ID: covidwho-1598089

ABSTRACT

The current global pandemic due to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has taken a substantial number of lives across the world. Although few vaccines have been rolled-out, a number of vaccine candidates are still under clinical trials at various pharmaceutical companies and laboratories around the world. Considering the intrinsic nature of viruses in mutating and evolving over time, persistent efforts are needed to develop better vaccine candidates. In this study, various immuno-informatics tools and bioinformatics databases were deployed to derive consensus B-cell and T-cell epitope sequences of SARS-CoV-2 spike glycoprotein. This approach has identified four potential epitopes which have the capability to initiate both antibody and cell-mediated immune responses, are non-allergenic and do not trigger autoimmunity. These peptide sequences were also evaluated to show 99.82% of global population coverage based on the genotypic frequencies of HLA binding alleles for both MHC class-I and class-II and are unique for SARS-CoV-2 isolated from human as a host species. Epitope number 2 alone had a global population coverage of 98.2%. Therefore, we further validated binding and interaction of its constituent T-cell epitopes with their corresponding HLA proteins using molecular docking and molecular dynamics simulation experiments, followed by binding free energy calculations with molecular mechanics Poisson-Boltzmann surface area, essential dynamics analysis and free energy landscape analysis. The immuno-informatics pipeline described and the candidate epitopes discovered herein could have significant impact upon efforts to develop globally effective SARS-CoV-2 vaccines.


Subject(s)
COVID-19 Vaccines , Epitopes, B-Lymphocyte , Epitopes, T-Lymphocyte , Molecular Docking Simulation , SARS-CoV-2 , COVID-19 Vaccines/chemistry , COVID-19 Vaccines/immunology , Epitopes, B-Lymphocyte/chemistry , Epitopes, B-Lymphocyte/immunology , Epitopes, T-Lymphocyte/chemistry , Epitopes, T-Lymphocyte/immunology , Humans , SARS-CoV-2/chemistry , SARS-CoV-2/immunology , Vaccines, Subunit/chemistry , Vaccines, Subunit/immunology
11.
Front Immunol ; 12: 789905, 2021.
Article in English | MEDLINE | ID: covidwho-1581321

ABSTRACT

Facing the imminent need for vaccine candidates with cross-protection against globally circulating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mutants, we present a conserved antigenic peptide RBD9.1 with both T-cell and B-cell epitopes. RBD9.1 can be recognized by coronavirus disease 2019 (COVID-19) convalescent serum, particularly for those with high neutralizing potency. Immunization with RBD9.1 can successfully induce the production of the receptor-binding domain (RBD)-specific antibodies in Balb/c mice. Importantly, the immunized sera exhibit sustained neutralizing efficacy against multiple dominant SARS-CoV-2 variant strains, including B.1.617.2 that carries a point mutation (SL452R) within the sequence of RBD9.1. Specifically, SY451 and SY454 are identified as the key amino acids for the binding of the induced RBD-specific antibodies to RBD9.1. Furthermore, we have confirmed that the RBD9.1 antigenic peptide can induce a S448-456 (NYNYLYRLF)-specific CD8+ T-cell response. Both RBD9.1-specific B cells and the S448-456-specific T cells can still be activated more than 3 months post the last immunization. This study provides a potential vaccine candidate that can generate long-term protective efficacy over SARS-CoV-2 variants, with the unique functional mechanism of activating both humoral and cellular immunity.


Subject(s)
Antibodies, Viral/immunology , COVID-19 Vaccines/immunology , COVID-19/prevention & control , Immunity, Cellular/immunology , Immunity, Humoral/immunology , Animals , Antibodies, Neutralizing/immunology , COVID-19 Vaccines/pharmacology , Epitopes, B-Lymphocyte/immunology , Epitopes, T-Lymphocyte/immunology , Humans , Mice , Mice, Inbred BALB C , SARS-CoV-2/immunology , Vaccines, Subunit/immunology
12.
Front Immunol ; 12: 772240, 2021.
Article in English | MEDLINE | ID: covidwho-1551510

ABSTRACT

Antigen-specific tissue-resident memory T cells (Trms) and neutralizing IgA antibodies provide the most effective protection of the lungs from viral infections. To induce those essential components of lung immunity against SARS-CoV-2, we tested various immunization protocols involving intranasal delivery of a novel Modified Vaccinia virus Ankara (MVA)-SARS-2-spike vaccine candidate. We show that a single intranasal MVA-SARS-CoV-2-S application in mice strongly induced pulmonary spike-specific CD8+ T cells, albeit restricted production of neutralizing antibodies. In prime-boost protocols, intranasal booster vaccine delivery proved to be crucial for a massive expansion of systemic and lung tissue-resident spike-specific CD8+ T cells and the development of Th1 - but not Th2 - CD4+ T cells. Likewise, very high titers of IgG and IgA anti-spike antibodies were present in serum and broncho-alveolar lavages that possessed high virus neutralization capacities to all current SARS-CoV-2 variants of concern. Importantly, the MVA-SARS-2-spike vaccine applied in intramuscular priming and intranasal boosting treatment regimen completely protected hamsters from developing SARS-CoV-2 lung infection and pathology. Together, these results identify intramuscular priming followed by respiratory tract boosting with MVA-SARS-2-S as a promising approach for the induction of local, respiratory as well as systemic immune responses suited to protect from SARS-CoV-2 infections.


Subject(s)
Antibodies, Viral/blood , CD8-Positive T-Lymphocytes/immunology , COVID-19 Vaccines/immunology , COVID-19/prevention & control , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Administration, Intranasal , Animals , Antibodies, Neutralizing/blood , Cell Line , Chlorocebus aethiops , Cricetinae , Genetic Vectors , Immunization, Secondary , Immunoglobulin A/blood , Immunoglobulin G/blood , Lung/immunology , Male , Mice , Mice, Inbred C57BL , Th1 Cells/immunology , Vaccination , Vaccines, Subunit/immunology , Vaccinia virus/immunology , Vero Cells , Viral Load/immunology
13.
Virology ; 566: 56-59, 2022 01.
Article in English | MEDLINE | ID: covidwho-1550137

ABSTRACT

BACKGROUND: Recombinant protein subunit vaccination is considered to be a safe, fast and reliable technique when combating emerging and re-emerging diseases such as coronavirus disease 2019 (COVID-19). Typically, such subunit vaccines require the addition of adjuvants to attain adequate immunogenicity. AS01, which contains adjuvants MPL and saponin QS21, is a liposome-based vaccine adjuvant system that is one of the leading candidates. However, the adjuvant effect of AS01 in COVID-19 vaccines is not well described yet. METHODS: In this study, we utilized a mixture of AS01 as the adjuvant for an S1 protein-based COVID-19 vaccine. RESULTS: The adjuvanted vaccine induced robust immunoglobulin G (IgG) binding antibody and virus-neutralizing antibody responses. Importantly, two doses induced similar levels of IgG binding antibody and neutralizing antibody responses compared with three doses and the antibody responses weakened only slightly over time up to six weeks after immunization. CONCLUSION: These results suggested that two doses may be enough for a clinical vaccine strategy design using MPL & QS21 adjuvanted recombinant protein, especially in consideration of the limited production capacity of COVID-19 vaccine in a public health emergency.


Subject(s)
Antigens, Viral/immunology , COVID-19 Vaccines/immunology , COVID-19/immunology , Lipid A/analogs & derivatives , SARS-CoV-2/immunology , Saponins/immunology , Spike Glycoprotein, Coronavirus/immunology , Vaccines, Subunit/immunology , Adjuvants, Immunologic/administration & dosage , Animals , Antibodies, Neutralizing , Antibodies, Viral/metabolism , Antibody Formation , COVID-19/virology , Dose-Response Relationship, Immunologic , Drug Combinations , Female , HEK293 Cells , Humans , Immunization , Immunogenicity, Vaccine , Lipid A/administration & dosage , Lipid A/immunology , Mice, Inbred BALB C , Recombinant Proteins/administration & dosage , Recombinant Proteins/immunology , Saponins/administration & dosage
14.
Nature ; 601(7894): 617-622, 2022 01.
Article in English | MEDLINE | ID: covidwho-1528018

ABSTRACT

T cell immunity is central for the control of viral infections. CoVac-1 is a peptide-based vaccine candidate, composed of SARS-CoV-2 T cell epitopes derived from various viral proteins1,2, combined with the Toll-like receptor 1/2 agonist XS15 emulsified in Montanide ISA51 VG, aiming to induce profound SARS-CoV-2 T cell immunity to combat COVID-19. Here we conducted a phase I open-label trial, recruiting 36 participants aged 18-80 years, who received a single subcutaneous CoVac-1 vaccination. The primary end point was safety analysed until day 56. Immunogenicity in terms of CoVac-1-induced T cell response was analysed as the main secondary end point until day 28 and in the follow-up until month 3. No serious adverse events and no grade 4 adverse events were observed. Expected local granuloma formation was observed in all study participants, whereas systemic reactogenicity was absent or mild. SARS-CoV-2-specific T cell responses targeting multiple vaccine peptides were induced in all study participants, mediated by multifunctional T helper 1 CD4+ and CD8+ T cells. CoVac-1-induced IFNγ T cell responses persisted in the follow-up analyses and surpassed those detected after SARS-CoV-2 infection as well as after vaccination with approved vaccines. Furthermore, vaccine-induced T cell responses were unaffected by current SARS-CoV-2 variants of concern. Together, CoVac-1 showed a favourable safety profile and induced broad, potent and variant of concern-independent T cell responses, supporting the presently ongoing evaluation in a phase II trial for patients with B cell or antibody deficiency.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19/immunology , SARS-CoV-2/immunology , T-Lymphocytes/immunology , Vaccines, Subunit/immunology , Administration, Cutaneous , Adolescent , Adult , Aged , Aged, 80 and over , CD8-Positive T-Lymphocytes/immunology , COVID-19/prevention & control , COVID-19/virology , COVID-19 Vaccines/administration & dosage , COVID-19 Vaccines/adverse effects , Clinical Trials, Phase II as Topic , Female , Granuloma/immunology , Humans , Immunogenicity, Vaccine , Interferon-gamma/immunology , Male , Middle Aged , T-Lymphocytes, Helper-Inducer/immunology , Vaccines, Subunit/administration & dosage , Vaccines, Subunit/adverse effects , Young Adult
15.
Front Immunol ; 12: 732298, 2021.
Article in English | MEDLINE | ID: covidwho-1506693

ABSTRACT

Immune modulating therapies and vaccines are in high demand, not least to the recent global spread of SARS-CoV2. To achieve efficient activation of the immune system, professional antigen presenting cells have proven to be key coordinators of such responses. Especially targeted approaches, actively directing antigens to specialized dendritic cells, promise to be more effective and accompanied by reduced payload due to less off-target effects. Although antibody and glycan-based targeting of receptors on dendritic cells have been employed, these are often expensive and time-consuming to manufacture or lack sufficient specificity. Thus, we applied a small-molecule ligand that specifically binds Langerin, a hallmark receptor on Langerhans cells, conjugated to a model protein antigen. Via microneedle injection, this construct was intradermally administered into intact human skin explants, selectively loading Langerhans cells in the epidermis. The ligand-mediated cellular uptake outpaces protein degradation resulting in intact antigen delivery. Due to the pivotal role of Langerhans cells in induction of immune responses, this approach of antigen-targeting of tissue-resident immune cells offers a novel way to deliver highly effective vaccines with minimally invasive administration.


Subject(s)
Antigens, CD/metabolism , Antigens/administration & dosage , Green Fluorescent Proteins/administration & dosage , Langerhans Cells/metabolism , Lectins, C-Type/metabolism , Mannose-Binding Lectins/metabolism , Animals , Antigens/immunology , Antigens/metabolism , COS Cells , Chlorocebus aethiops , Green Fluorescent Proteins/metabolism , HEK293 Cells , Humans , Injections, Intradermal , Langerhans Cells/immunology , Ligands , Miniaturization , Nanomedicine , Needles , Protein Binding , Protein Transport , Proteolysis , THP-1 Cells , Vaccines, Subunit/administration & dosage , Vaccines, Subunit/immunology , Vaccines, Subunit/metabolism
17.
Viruses ; 13(11)2021 11 02.
Article in English | MEDLINE | ID: covidwho-1502527

ABSTRACT

The COVID-19 pandemic has currently created an unprecedented threat to human society and global health. A rapid mass vaccination to create herd immunity against SARS-CoV-2 is a crucial measure to ease the spread of this disease. Here, we investigated the immunogenicity of a SARS-CoV-2 subunit vaccine candidate, a SARS-CoV-2 spike glycoprotein encapsulated in N,N,N-trimethyl chitosan particles or S-TMC NPs. Upon intraperitoneal immunization, S-TMC NP-immunized mice elicited a stronger systemic antibody response, with neutralizing capacity against SARS-CoV-2, than mice receiving the soluble form of S-glycoprotein. S-TMC NPs were able to stimulate the circulating IgG and IgA as found in SARS-CoV-2-infected patients. In addition, spike-specific T cell responses were drastically activated in S-TMC NP-immunized mice. Surprisingly, administration of S-TMC NPs via the intraperitoneal route also stimulated SARS-CoV-2-specific immune responses in the respiratory tract, which were demonstrated by the presence of high levels of SARS-CoV-2-specific IgG and IgA in the lung homogenates and bronchoalveolar lavages of the immunized mice. We found that peritoneal immunization with spike nanospheres stimulates both systemic and respiratory mucosal immunity.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19/immunology , COVID-19/virology , Immunity , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Vaccines, Subunit/immunology , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , Antibody Formation , COVID-19/prevention & control , Female , Humans , Immunity, Mucosal , Immunization/methods , Immunogenicity, Vaccine , Mice , Mice, Inbred BALB C , Nanoparticles/therapeutic use , Recombinant Proteins/immunology , Respiratory System/immunology , T-Lymphocytes/immunology , Vaccination , Vaccines, Subunit/administration & dosage
18.
Cells ; 10(11)2021 11 04.
Article in English | MEDLINE | ID: covidwho-1502369

ABSTRACT

During the current era of the COVID-19 pandemic, the dissemination of Mucorales has been reported globally, with elevated rates of infection in India, and because of the high rate of mortality and morbidity, designing an effective vaccine against mucormycosis is a major health priority, especially for immunocompromised patients. In the current study, we studied shared Mucorales proteins, which have been reported as virulence factors, and after analysis of several virulent proteins for their antigenicity and subcellular localization, we selected spore coat (CotH) and serine protease (SP) proteins as the targets of epitope mapping. The current study proposes a vaccine constructed based on top-ranking cytotoxic T lymphocyte (CTL), helper T lymphocyte (HTL), and B cell lymphocyte (BCL) epitopes from filtered proteins. In addition to the selected epitopes, ß-defensins adjuvant and PADRE peptide were included in the constructed vaccine to improve the stimulated immune response. Computational tools were used to estimate the physicochemical and immunological features of the proposed vaccine and validate its binding with TLR-2, where the output data of these assessments potentiate the probability of the constructed vaccine to stimulate a specific immune response against mucormycosis. Here, we demonstrate the approach of potential vaccine construction and assessment through computational tools, and to the best of our knowledge, this is the first study of a proposed vaccine against mucormycosis based on the immunoinformatics approach.


Subject(s)
Fungal Vaccines/chemistry , Fungal Vaccines/immunology , Mucormycosis/prevention & control , Rhizopus/immunology , Adjuvants, Immunologic , Antigens, Fungal/immunology , Computational Biology , Cross Reactions , Epitope Mapping , Epitopes, B-Lymphocyte/chemistry , Epitopes, B-Lymphocyte/immunology , Epitopes, T-Lymphocyte/chemistry , Epitopes, T-Lymphocyte/immunology , Humans , Models, Molecular , Mucorales/immunology , Protein Conformation , Toll-Like Receptor 2/chemistry , Vaccines, Subunit/chemistry , Vaccines, Subunit/immunology
19.
Adv Drug Deliv Rev ; 179: 114020, 2021 12.
Article in English | MEDLINE | ID: covidwho-1486938

ABSTRACT

Adjuvant is an essential component in subunit vaccines. Many agonists of pathogen recognition receptors have been developed as potent adjuvants to optimize the immunogenicity and efficacy of vaccines. Recently discovered cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway has attracted much attention as it is a key mediator for modulating immune responses. Vaccines adjuvanted with STING agonists are found to mediate a robust immune defense against infections and cancer. In this review, we first discuss the mechanisms of STING agonists in the context of vaccination. Next, we present recent progress in novel STING agonist discovery and the delivery strategies. We next highlight recent work in optimizing the efficacy while minimizing toxicity of STING agonist-assisted subunit vaccines for protection against infectious diseases or treatment of cancer. Finally, we share our perspectives of current issues and future directions in further developing STING agonists for adjuvanting subunit vaccines.


Subject(s)
Adjuvants, Immunologic/administration & dosage , Membrane Proteins/agonists , Membrane Proteins/immunology , Vaccines, Subunit/immunology , CD4-Positive T-Lymphocytes/drug effects , CD8-Positive T-Lymphocytes/drug effects , Dendritic Cells/drug effects , Humans , Immunity, Humoral/drug effects , Nucleotidyltransferases/metabolism
20.
Viruses ; 13(10)2021 09 28.
Article in English | MEDLINE | ID: covidwho-1481007

ABSTRACT

Nipah virus (NiV) and respiratory syncytial virus (RSV) possess two surface glycoproteins involved in cellular attachment and membrane fusion, both of which are potential targets for vaccines. The majority of vaccine development is focused on the attachment (G) protein of NiV, which is the immunodominant target. In contrast, the fusion (F) protein of RSV is the main target in vaccine development. Despite this, neutralising epitopes have been described in NiV F and RSV G, making them alternate targets for vaccine design. Through rational design, we have developed a vaccine strategy applicable to phylogenetically divergent NiV and RSV that comprises both the F and G proteins (FxG). In a mouse immunization model, we found that NiV FxG elicited an improved immune response capable of neutralising pseudotyped NiV and a NiV mutant that is able to escape neutralisation by two known F-specific antibodies. RSV FxG elicited an immune response against both F and G and was able to neutralise RSV; however, this was inferior to the immune response of F alone. Despite this, RSV FxG elicited a response against a known protective epitope within G that is conserved across RSV A and B subgroups, which may provide additional protection in vivo. We conclude that inclusion of F and G antigens within a single design provides a streamlined subunit vaccine strategy against both emerging and established pathogens, with the potential for broader protection against NiV.


Subject(s)
Antibodies, Viral/blood , Henipavirus Infections/prevention & control , Nipah Virus/immunology , Respiratory Syncytial Virus Infections/prevention & control , Respiratory Syncytial Virus Vaccines/immunology , Respiratory Syncytial Virus, Human/immunology , Viral Envelope Proteins/immunology , Animals , Antibodies, Viral/immunology , Female , Humans , Mice , Mice, Inbred BALB C , Respiratory Syncytial Virus Vaccines/administration & dosage , Vaccines, Subunit/administration & dosage , Vaccines, Subunit/immunology , Viral Envelope Proteins/administration & dosage , Viral Envelope Proteins/genetics , Viral Fusion Proteins/immunology
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