SARS-CoV-2 protein subunit vaccination elicits potent neutralizing antibody responses

Mandolesi, Marco; Sheward, Daniel J.; Hanke, Leo; Ma, Junjie; Pushparaj, Pradeepa; Vidakovics, Laura Perez; Kim, Chang-Il; Loré, Karin; Dopico, Xaquín Castro; Coquet, Jonathan M.; McInerney, Gerald M.; Hedestam, Gunilla B. Karlsson; Murrell, Ben

doi:10.1101/2020.07.31.228486

Cited by 16 publications

(18 citation statements)

References 38 publications

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“…The higher ratio of neutralizing to binding antibodies obtained in the present work indicates a high quality of the antibodies generated by using the prefusion trimeric spike protein as the immunogen. Our results are in agreement with a previous comparison of mice immunized with the trimeric spike protein and the RBD, which showed higher neutralizing titers for the S protein 19 . This finding is probably related to the fact that other domains of the spike protein besides the RBD are also targets for neutralizing antibodies 20 .…”

Section: Discussionsupporting

confidence: 93%

Potent neutralizing equine antibodies raised against recombinant SARS-CoV-2 spike protein for COVID-19 passive immunization therapy

Cunha

Stolet

Strauch

et al. 2020

Preprint

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COVID-19 pandemic caused approximately 750,000 deaths and over 20 million confirmed cases of infection by SARS-CoV-2 within 8 months since the emergence of the virus. While there are no vaccines approved and considering the difficulty in meeting the large vaccination demand worldwide, the potential use of passive immunization should be considered based on existing successful therapies against many diseases. Here we demonstrate that hyperimmune globulin preparations raised in horses against the recombinant trimeric spike (S) glycoprotein of SARS-CoV-2 in the prefusion conformation provide very high ELISA titers as well as highly potent neutralizing activity against SARS-CoV-2. Five horses were subcutaneously inoculated for 6 weeks with the recombinant S protein (ectodomain, residues 1-1208). Four out of the 5 horses presented a strong immune response. Considering the average of all 5 horses, ELISA titers above 1:1,000,000 and neutralizing titers (PRNT90) reaching 1:14,604 were observed. When compared with the plasma of three convalescent COVID-19 patients, sera of immunized horses displayed approximately 140-fold higher neutralizing titers measured as PRNT90. To prevent eventual side effects caused by horse antiserum, IgG was digested with pepsin and purified by fractional salt precipitation to eliminate Fc fragments, a process that is industrially used for the production of passive immunization F(ab')2 concentrates against rabies, tetanus and snake venoms. The high neutralizing titers against SARS-CoV-2 obtained for the unprocessed sera were confirmed for the F(ab')2 fragments and were 150-fold higher than the PRNT90 neutralizing titers of plasma of three COVID-19 convalescent patients. The great advantage of using the recombinant trimeric S glycoprotein is that it is safe and provides quick adaptive immunity in horses. Our data show the perspective of using hyperimmune anti-SARS-CoV-2 F(ab')2 preparations as a passive immunization therapy in humans, similar to therapies that have been safely used for decades against rabies, tetanus and snake venoms.

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Section: Discussionsupporting

confidence: 93%

Potent neutralizing equine antibodies raised against recombinant SARS-CoV-2 spike protein for COVID-19 passive immunization therapy

Cunha

Stolet

Strauch

et al. 2020

Preprint

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“…Importantly, antisera from mice immunized with a single dose of either S-Fer or SΔC-Fer had ~2-fold higher mean neutralizing titers than those observed in a cohort of 20 convalescent COVID-19 plasma donors ( Figure 4C, far right). The lack of neutralizing titers after a single-dose immunization in both the RBD and SΔC-GCN4 groups and minimal neutralizing titers in the S-GCN4 group ( Figure 4C) are consistent with recent reports that also found a single dose of spike trimer or RBD was insufficient to elicit robust neutralizing antibodies in mice (65). Consistent with the lentiviral neutralization results ( Figure 4C), the only two groups with substantial ACE2-competing antibodies (as determined by a decrease in ACE2 binding to RBD on ELISA) were those immunized with spike ferritin nanoparticles ( Figure S6, left).…”

Section: Immunization With Spike-functionalized Nanoparticles Elicitssupporting

confidence: 91%

A single immunization with spike-functionalized ferritin vaccines elicits neutralizing antibody responses against SARS-CoV-2 in mice

Chen

Zhang

Sanyal

et al. 2020

Preprint

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Development of a safe and effective SARS-CoV-2 vaccine is a public health priority. We designed subunit vaccine candidates using self-assembling ferritin nanoparticles displaying one of two multimerized SARS-CoV-2 spikes: full-length ectodomain (S-Fer) or a C-terminal 70 amino-acid deletion (SΔC-Fer). Ferritin is an attractive nanoparticle platform for production of vaccines and ferritin-based vaccines have been investigated in humans in two separate clinical trials. We confirmed proper folding and antigenicity of spike on the surface of ferritin by cryo-EM and binding to conformation-specific monoclonal antibodies. After a single immunization of mice with either of the two spike ferritin particles, a lentiviral SARS-CoV-2 pseudovirus assay revealed mean neutralizing antibody titers at least 2-fold greater than those in convalescent plasma from COVID-19 patients. Additionally, a single dose of SΔC-Fer elicited significantly higher neutralizing responses as compared to immunization with the spike receptor binding domain (RBD) monomer or spike ectodomain trimer alone. After a second dose, mice immunized with SΔC-Fer exhibited higher neutralizing titers than all other groups. Taken together, these results demonstrate that multivalent presentation of SARS-CoV-2 spike on ferritin can notably enhance elicitation of neutralizing antibodies, thus constituting a viable strategy for single-dose vaccination against COVID-19.

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“…For any vaccine intended to generate antibody-mediated immunity, delivering a conformationally correct antigen that maintains the surface contours of the native virus protein and preserves the epitopes required for eliciting high-quality neutralizing antibodies is critical 18 . It has been shown previously that conformational stability of www.nature.com/scientificreports/ SARS-CoV-2 spike protein translates into greater immunogenicity [49][50][51] and improved protein expression 52 which is particularly advantageous for gene-based antigen delivery. In our study, however, using an insert encoding the SARS-CoV-2 spike stabilized in its pre-fusion conformation did not improve the vaccine's immunogenicity.…”

Section: Discussionmentioning

confidence: 99%

DNA-launched RNA replicon vaccines induce potent anti-SARS-CoV-2 immune responses in mice

Szurgot

Hanke

Sheward

et al. 2021

Sci Rep

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The outbreak of the SARS-CoV-2 virus and its rapid spread into a global pandemic made the urgent development of scalable vaccines to prevent coronavirus disease (COVID-19) a global health and economic imperative. Here, we characterized and compared the immunogenicity of two alphavirus-based DNA-launched self-replicating (DREP) vaccine candidates encoding either SARS-CoV-2 spike glycoprotein (DREP-S) or a spike ectodomain trimer stabilized in prefusion conformation (DREP-Secto). We observed that the two DREP constructs were immunogenic in mice inducing both binding and neutralizing antibodies as well as T cell responses. Interestingly, the DREP coding for the unmodified spike turned out to be more potent vaccine candidate, eliciting high titers of SARS-CoV-2 specific IgG antibodies that were able to efficiently neutralize pseudotyped virus after a single immunization. In addition, both DREP constructs were able to efficiently prime responses that could be boosted with a heterologous spike protein immunization. These data provide important novel insights into SARS-CoV-2 vaccine design using a rapid response DNA vaccine platform. Moreover, they encourage the use of mixed vaccine modalities as a strategy to combat SARS-CoV-2.

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SARS-CoV-2 protein subunit vaccination elicits potent neutralizing antibody responses

Cited by 16 publications

References 38 publications

Potent neutralizing equine antibodies raised against recombinant SARS-CoV-2 spike protein for COVID-19 passive immunization therapy

Potent neutralizing equine antibodies raised against recombinant SARS-CoV-2 spike protein for COVID-19 passive immunization therapy

A single immunization with spike-functionalized ferritin vaccines elicits neutralizing antibody responses against SARS-CoV-2 in mice

DNA-launched RNA replicon vaccines induce potent anti-SARS-CoV-2 immune responses in mice

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