Use of eVLP-based vaccine candidates to broaden immunity against SARS-CoV-2 variants

Rapid emergence of SARS-CoV-2 variants is a constant threat and a major hurdle to reach heard immunity. We produced VBI-2905a, an enveloped virus-like particules (eVLP)-based vaccine candidate expressing prefusion spike protein from the Beta variant that contains several escape mutation. VBI-2905a protected hamsters against infection with a Beta variant virus and induced high levels of neutralizing antibodies against Beta RBD. In a heterologous vaccination regimen, a single injection of VBI-2905a in animals previously immunized with VBI-2902, a vaccine candidate expressing S from ancestral SARS-CoV-2, hamsters were equally protected against Beta variant infection. As an alternate strategy to broaden immunity, we produced a trivalent vaccine expressing the prefusion spike protein from SARS-CoV-2 together with unmodifed S from SARS-CoV-1 and MERS-CoV. Relative to immunity induced against the ancestral strain, the trivalent vaccine VBI-2901a induced higher and more consistent antibody binding and neutralizing responses against a panel of variants including Beta, Delta, Kappa, and Lambda, with evidence for broadening of immunity rather than just boosting cross-reactivity antibodies.

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Immunomodulation in Administration of rAAV: Preclinical and Clinical Adjuvant Pharmacotherapies

Frontiers in Immunology ◽

10.3389/fimmu.2021.658038 ◽

2021 ◽

Vol 12 ◽

Author(s):

Wing Sum Chu ◽

Joanne Ng

Keyword(s):

Gene Therapy ◽

Immune Response ◽

Neutralizing Antibodies ◽

Normal Population ◽

Clinical Stage ◽

Adaptive Immune Response ◽

The United States ◽

Cross Reactivity ◽

Target Cells ◽

Enveloped Virus

Recombinant adeno-associated virus (rAAV) has attracted a significant research focus for delivering genetic therapies to target cells. This non-enveloped virus has been trialed in many clinical-stage therapeutic strategies but important obstacle in clinical translation is the activation of both innate and adaptive immune response to the protein capsid, vector genome and transgene product. In addition, the normal population has pre-existing neutralizing antibodies against wild-type AAV, and cross-reactivity is observed between different rAAV serotypes. While extent of response can be influenced by dosing, administration route and target organ(s), these pose concerns over reduction or complete loss of efficacy, options for re-administration, and other unwanted immunological sequalae such as local tissue damage. To reduce said immunological risks, patients are excluded if they harbor anti-AAV antibodies or have received gene therapy previously. Studies have incorporated immunomodulating or suppressive regimens to block cellular and humoral immune responses such as systemic corticosteroids pre- and post-administration of Luxturna® and Zolgensma®, the two rAAV products with licensed regulatory approval in Europe and the United States. In this review, we will introduce the current pharmacological strategies to immunosuppress or immunomodulate the host immune response to rAAV gene therapy.

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Comparative Immunomodulatory Evaluation of the Receptor Binding Domain of the SARS-CoV-2 Spike Protein; a Potential Vaccine Candidate Which Imparts Potent Humoral and Th1 Type Immune Response in a Mouse Model

Frontiers in Immunology ◽

10.3389/fimmu.2021.641447 ◽

2021 ◽

Vol 12 ◽

Author(s):

Tripti Shrivastava ◽

Balwant Singh ◽

Zaigham Abbas Rizvi ◽

Rohit Verma ◽

Sandeep Goswami ◽

...

Keyword(s):

Immune Response ◽

Receptor Binding ◽

Neutralizing Antibodies ◽

Vaccine Development ◽

Vaccine Candidate ◽

Unmet Need ◽

Binding Domain ◽

Spike Protein ◽

Cell Immune Response ◽

Receptor Binding Domain

The newly emerged novel coronavirus, SARS-CoV-2, the causative agent of COVID-19 has proven to be a threat to the human race globally, thus, vaccine development against SARS-CoV-2 is an unmet need driving mass vaccination efforts. The receptor binding domain of the spike protein of this coronavirus has multiple neutralizing epitopes and is associated with viral entry. Here we have designed and characterized the SARS-CoV-2 spike protein fragment 330-526 as receptor binding domain 330-526 (RBD330-526) with two native glycosylation sites (N331 and N343); as a potential subunit vaccine candidate. We initially characterized RBD330-526 biochemically and investigated its thermal stability, humoral and T cell immune response of various RBD protein formulations (with or without adjuvant) to evaluate the inherent immunogenicity and immunomodulatory effect. Our result showed that the purified RBD immunogen is stable up to 72 h, without any apparent loss in affinity or specificity of interaction with the ACE2 receptor. Upon immunization in mice, RBD generates a high titer humoral response, elevated IFN-γ producing CD4+ cells, cytotoxic T cells, and robust neutralizing antibodies against live SARS-CoV-2 virus. Our results collectively support the potential of RBD330-526 as a promising vaccine candidate against SARS-CoV-2.

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Potent binding of 2019 novel coronavirus spike protein by a SARS coronavirus-specific human monoclonal antibody

10.1101/2020.01.28.923011 ◽

2020 ◽

Cited By ~ 13

Author(s):

Xiaolong Tian ◽

Cheng Li ◽

Ailing Huang ◽

Shuai Xia ◽

Sicong Lu ◽

...

Keyword(s):

Monoclonal Antibody ◽

Binding Site ◽

Neutralizing Antibodies ◽

Rapid Development ◽

Antiviral Treatment ◽

Human Monoclonal Antibody ◽

Cross Reactivity ◽

Spike Protein ◽

The Cross ◽

Novel Coronavirus

ABSTRACTThe newly identified 2019 novel coronavirus (2019-nCoV) has caused more than 800 laboratory-confirmed human infections, including 25 deaths, posing a serious threat to human health. Currently, however, there is no specific antiviral treatment or vaccine. Considering the relatively high identity of receptor binding domain (RBD) in 2019-nCoV and SARS-CoV, it is urgent to assess the cross-reactivity of anti-SARS-CoV antibodies with 2019-nCoV spike protein, which could have important implications for rapid development of vaccines and therapeutic antibodies against 2019-nCoV. Here, we report for the first time that a SARS-CoV-specific human monoclonal antibody, CR3022, could bind potently with 2019-nCoV RBD (KD of 6.3 nM). The epitope of CR3022 does not overlap with the ACE2 binding site within 2019-nCoV RBD. Therefore, CR3022 has the potential to be developed as candidate therapeutics, alone or in combination with other neutralizing antibodies, for the prevention and treatment of 2019-nCoV infections. Interestingly, some of the most potent SARS-CoV-specific neutralizing antibodies (e.g., m396, CR3014) that target the ACE2 binding site of SARS-CoV failed to bind 2019-nCoV spike protein, indicating that the difference in the RBD of SARS-CoV and 2019-nCoV has a critical impact for the cross-reactivity of neutralizing antibodies, and that it is still necessary to develop novel monoclonal antibodies that could bind specifically to 2019-nCoV RBD.

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A single dose, BCG-adjuvanted SARS-CoV-2 vaccine induces Th1-polarized immunity and high-titre neutralizing antibodies in mice

10.1101/2020.12.10.419044 ◽

2020 ◽

Author(s):

Claudio Counoupas ◽

Alberto O. Stella ◽

Nayan D. Bhattacharyya ◽

Alice Grey ◽

Karishma Patel ◽

...

Keyword(s):

Single Dose ◽

Neutralizing Antibodies ◽

Protective Immunity ◽

Vaccine Candidate ◽

Rapid Development ◽

Population Level ◽

High Titre ◽

Spike Protein ◽

Cold Chain ◽

Igg Antibody

AbstractNext-generation vaccines that are safe, effective and with equitable access globally are required to prevent SARS-CoV-2 transmission at a population level. One strategy that has gained significant interest is to ‘repurpose’ existing licensed vaccines for use against COVID-19. In this report, we have exploited the immunostimulatory properties of bacille Calmette-Guérin (BCG), the vaccine for tuberculosis, to develop a SARS-CoV-2-specific and highly immunogenic vaccine candidate. Combination of BCG with a stabilized, trimeric form of the SARS-CoV-2 spike antigen promoted rapid development of virus-specific IgG antibodies in the sera of vaccinated mice, which could be further augmented by the addition of alum. This vaccine formulation, termed BCG:CoVac, induced a Th1-biased response both in terms of IgG antibody subclass and cytokine release by vaccine-specific CD4+ and CD8+ T cells. A single dose of BCG:CoVac was sufficient to induce high-titre SARS-CoV-2 neutralizing antibodies (NAbs) that were detectable as early as 2 weeks post-vaccination; NAb levels were greater than that seen in the sera of SARS-CoV-2-infected individuals. Boosting of BCG:CoVac-primed mice with a heterologous vaccine combination (spike protein plus alum) could further increase SARS-CoV-2 spike protein-specific antibody response. BCG:CoVac would be broadly applicable for all populations susceptible to SARS-CoV-2 infection and in particular could be readily incorporated into current vaccine schedules in countries where BCG is currently used.ImportanceEffective distribution of vaccine to low- and middle-income countries is critical for the control of the COVID-19 pandemic. To achieve this, vaccines must offer effective protective immunity yet should be cheap to manufacture and meet cold chain management requirements. This study describes a unique COVID-19 vaccine candidate, termed BCG:CoVac, that when delivered as a single dose induces potent SARS-CoV-2 specific immunity in mice, particularly through generation of high-titre, anti-viral neutralising antibodies. BCG:CoVac is built on safe and well-characterised vaccine components: 1) the BCG vaccine, used for control of tuberculosis since 1921 which also has remarkable ‘off target’ effects, protecting children and the elderly against diverse respiratory viral infections; 2) Alhydrogel adjuvant (Alum), a low cost, globally accessible vaccine adjuvant with an excellent safety record in humans (part of >20 licensed human vaccines and in use >70 years); 3) Stabilized, trimeric SARS-CoV-2 spike protein, which stimulates immune specificity for COVID-19. Further assessment in humans will determine if BCG:CoVac can impart protective immunity against not only SARS-CoV-2, but also other respiratory infections where BCG has known efficacy.

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An enveloped virus-like particle vaccine expressing a stabilized prefusion form of the SARS-CoV-2 spike protein elicits potent immunity after a single dose

10.1101/2021.04.28.441832 ◽

2021 ◽

Author(s):

Anne-Catherine Fluckiger ◽

Barthelemy Ontsouka ◽

Jasminka Bozic ◽

Abebaw Diress ◽

Tanvir Ahmed ◽

...

Keyword(s):

Single Dose ◽

Vaccine Candidate ◽

Aluminum Phosphate ◽

Antibody Binding ◽

Spike Protein ◽

List Type ◽

Enveloped Virus ◽

Virus Like Particle ◽

Syrian Golden Hamsters ◽

Dose Vaccine

AbstractDevelopment of efficacious single dose vaccines would substantially aid efforts to stop the uncontrolled spread of the COVID-19 pandemic. We evaluated enveloped virus-like particles (eVLPs) expressing various forms of the SARS-CoV-2 spike protein and several adjuvants in an effort to identify a COVID-19 vaccine candidate efficacious after a single dose. The eVLPs expressing a modified prefusion form of SARS-CoV-2 spike protein were selected as they induced the highest antibody binding titers and neutralizing activity after a single injection in mice. Formulation of SARS-CoV-2 S eVLPs with aluminum phosphate resulted in balanced induction of IgG2 and IgG1 isotypes and antibody binding and neutralization titers were undiminished for more than 3 months after a single immunization. A single dose of this candidate, VBI-2902a (prefusion S eVLPs formulated with aluminum phosphate), protected Syrian golden hamsters from challenge with SARS-CoV-2 and supports the on-going clinical evaluation of VBI-2902a as a potential single dose vaccine against COVID-19.HighlightsVBI-2902a is a VLP-based vaccine candidate against SARS-COV-2VBI-2902a contains VLPs pseudotyped with a modified prefusion SARS-COV-2 S in Alum.VBI-2902a induces robust neutralization antibody response against SARS-COV-2 SVBI-2902a protects hamsters from SARS-CoV-2 induced lung inflammationA single dose of VBI-2902a provides protective benefit in hamsters

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A SARS-CoV-2 vaccine candidate would likely match all currently circulating variants

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2008281117 ◽

2020 ◽

Vol 117 (38) ◽

pp. 23652-23662 ◽

Cited By ~ 25

Author(s):

Bethany Dearlove ◽

Eric Lewitus ◽

Hongjun Bai ◽

Yifan Li ◽

Daniel B. Reeves ◽

...

Keyword(s):

Viral Entry ◽

Neutralizing Antibodies ◽

Vaccine Candidate ◽

Spike Protein ◽

Reference Sequence ◽

Viral Population ◽

Effective Vaccine ◽

Nucleotide Substitutions ◽

Bioinformatics Analyses ◽

Vaccine Candidates

The magnitude of the COVID-19 pandemic underscores the urgency for a safe and effective vaccine. Many vaccine candidates focus on the Spike protein, as it is targeted by neutralizing antibodies and plays a key role in viral entry. Here we investigate the diversity seen in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequences and compare it to the sequence on which most vaccine candidates are based. Using 18,514 sequences, we perform phylogenetic, population genetics, and structural bioinformatics analyses. We find limited diversity across SARS-CoV-2 genomes: Only 11 sites show polymorphisms in >5% of sequences; yet two mutations, including the D614G mutation in Spike, have already become consensus. Because SARS-CoV-2 is being transmitted more rapidly than it evolves, the viral population is becoming more homogeneous, with a median of seven nucleotide substitutions between genomes. There is evidence of purifying selection but little evidence of diversifying selection, with substitution rates comparable across structural versus nonstructural genes. Finally, the Wuhan-Hu-1 reference sequence for the Spike protein, which is the basis for different vaccine candidates, matches optimized vaccine inserts, being identical to an ancestral sequence and one mutation away from the consensus. While the rapid spread of the D614G mutation warrants further study, our results indicate that drift and bottleneck events can explain the minimal diversity found among SARS-CoV-2 sequences. These findings suggest that a single vaccine candidate should be efficacious against currently circulating lineages.

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Structural analysis of full-length SARS-CoV-2 spike protein from an advanced vaccine candidate

Science ◽

10.1126/science.abe1502 ◽

2020 ◽

Vol 370 (6520) ◽

pp. 1089-1094 ◽

Cited By ~ 5

Author(s):

Sandhya Bangaru ◽

Gabriel Ozorowski ◽

Hannah L. Turner ◽

Aleksandar Antanasijevic ◽

Deli Huang ◽

...

Keyword(s):

Immune Responses ◽

Neutralizing Antibodies ◽

Subunit Vaccine ◽

Structural Integrity ◽

Vaccine Candidate ◽

Full Length ◽

Spike Protein ◽

Primary Target ◽

Site Specific ◽

Vaccine Candidates

Vaccine efforts to combat the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the current coronavirus disease 2019 (COVID-19) pandemic, are focused on SARS-CoV-2 spike glycoprotein, the primary target for neutralizing antibodies. We performed cryo–election microscopy and site-specific glycan analysis of one of the leading subunit vaccine candidates from Novavax, which is based on a full-length spike protein formulated in polysorbate 80 detergent. Our studies reveal a stable prefusion conformation of the spike immunogen with slight differences in the S1 subunit compared with published spike ectodomain structures. We also observed interactions between the spike trimers, allowing formation of higher-order spike complexes. This study confirms the structural integrity of the full-length spike protein immunogen and provides a basis for interpreting immune responses to this multivalent nanoparticle immunogen.

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Antibody responses to endemic coronaviruses modulate COVID-19 convalescent plasma functionality

10.1101/2020.12.16.20248294 ◽

2020 ◽

Author(s):

William Morgenlander ◽

Stephanie Henson ◽

Daniel Monaco ◽

Athena Chen ◽

Kirsten Littlefield ◽

...

Keyword(s):

Polyclonal Antibody ◽

Strong Correlation ◽

Neutralizing Antibodies ◽

High Titer ◽

Fusion Peptide ◽

Cross Reactivity ◽

Antibody Responses ◽

Spike Protein ◽

Receptor Binding Domain ◽

Human Coronavirus

AbstractCOVID-19 convalescent plasma, particularly plasma with high-titer SARS-CoV-2 (CoV2) antibodies, has been successfully used for treatment of COVID-19. The functionality of convalescent plasma varies greatly, but the association of antibody epitope specificities with plasma functionality remains uncharacterized. We assessed antibody functionality and reactivities to peptides across the CoV2 and the four endemic human coronavirus (HCoV) genomes in 126 COVID-19 convalescent plasma donations. We found strong correlation between plasma functionality and polyclonal antibody targeting of CoV2 spike protein peptides. Antibody reactivity to many HCoV spike peptides also displayed strong correlation with plasma functionality, including pan-coronavirus cross-reactive epitopes located in a conserved region of the fusion peptide. After accounting for antibody cross-reactivity, we identified an association between greater alphacoronavirus NL63 antibody responses and development of highly neutralizing antibodies to SARS-CoV-2. We also found that plasma preferentially reactive to the CoV2 receptor binding domain (RBD), versus the betacoronavirus HKU1 RBD, had higher neutralizing titer. Finally, we developed a two-peptide serosignature that identifies plasma donations with high anti-S titer but that suffer from low neutralizing activity. These results suggest that analysis of coronavirus antibody fine specificities may be useful for selecting therapeutic plasma with desired functionalities.

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Potent neutralization antibodies induced by a recombinant trimeric Spike protein vaccine candidate containing PIKA adjuvant for COVID-19

10.1101/2021.02.17.431647 ◽

2021 ◽

Author(s):

Jiao Tong ◽

Chenxi Zhu ◽

Hanyu Lai ◽

Chunchao Feng ◽

Dapeng Zhou

Keyword(s):

Neutralizing Antibodies ◽

Vaccine Candidate ◽

Natural Infection ◽

Spike Protein ◽

Heptad Repeat ◽

Protein Vaccine ◽

Direct Binding ◽

Linear Epitopes ◽

Virus System ◽

Potent Neutralization

AbstractNeutralizing antibodies are critical to prevent corona virus infection. The structures of immunogens to elicit most potent neutralization antibodies are still under investigation. Here we tested the immunogenicity of the trimeric, full length Spike protein with 2 proline mutations to preserve its prefusion conformation. Recombinant trimeric Spike protein expressed by CHO cells was used with polyI:C (PIKA) adjuvant to immunize mice by 0-7-14 day schedule. The results showed that Spike-specific antibody was induced at day 21 with titer of more than 50,000 in average as measured by direct binding to Spike protein. The titer of neutralization reached more than 1000 in average when tested by a pseudo-virus system, using monoclonal antibodies (40592-MM57 and 40591-MM43) with neutralizing IC50 at 1 μg/ml as standards. Protein/peptide array showed that the antibodies induced by trimeric S protein vaccine bind similarly to natural infection with the receptor binding domain (RBD) as major immunodominant region. No linear epitopes were found in RBD, although several linear epitopes were found in C-terminal domain right after RBD, and heptad repeat regions. Our study supports the efficacy of recombinant trimeric Spike protein vaccine candidate for COVID-19, with excellent safety and readiness for storage and distribution in developing countries.

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Structural analysis of full-length SARS-CoV-2 spike protein from an advanced vaccine candidate

10.1101/2020.08.06.234674 ◽

2020 ◽

Cited By ~ 2

Author(s):

Sandhya Bangaru ◽

Gabriel Ozorowski ◽

Hannah L. Turner ◽

Aleksandar Antanasijevic ◽

Deli Huang ◽

...

Keyword(s):

Immune Responses ◽

Neutralizing Antibodies ◽

Structural Integrity ◽

Vaccine Candidate ◽

Full Length ◽

Spike Protein ◽

Primary Target ◽

Site Specific ◽

Vaccine Candidates ◽

Novel Interactions

AbstractVaccine efforts against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) responsible for the current COVID-19 pandemic are focused on SARS-CoV-2 spike glycoprotein, the primary target for neutralizing antibodies. Here, we performed cryo-EM and site-specific glycan analysis of one of the leading subunit vaccine candidates from Novavax based on a full-length spike protein formulated in polysorbate 80 (PS 80) detergent. Our studies reveal a stable prefusion conformation of the spike immunogen with slight differences in the S1 subunit compared to published spike ectodomain structures. Interestingly, we also observed novel interactions between the spike trimers allowing formation of higher order spike complexes. This study confirms the structural integrity of the full-length spike protein immunogen and provides a basis for interpreting immune responses to this multivalent nanoparticle immunogen.

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