Here, we have demonstrated that a dose of either S-Fer or SC-Fer nanoparticles adjuvanted with Quil-A and MPLA was sufficient to accomplish neutralizing titers greater than those in plasma from convalescent COVID-19 individuals. Additionally, both S-Fer and SC-Fer form nanoparticles spontaneously following expression in mammalian cells without the need for any conjugation step, showcasing the potential software of spike ferritin constructs to nucleic acid-based vaccine strategies. neutralizing antibodies, therefore constituting a viable strategy for single-dose vaccination against COVID-19. == Short abstract == Multivalent SARS-CoV-2 spike displayed on a self-assembling ferritin nanoparticle elicits a more powerful neutralizing antibody response in mice following single AAI101 immunization as compared to spike only. == Intro == The emergence of SARS-CoV-2 in the human population in 2019 offers caused a rapidly growing pandemic that has disrupted nearly all global infrastructures. To day, there have been over 63 million confirmed instances of COVID-19 and nearly 1.5 million deaths worldwide.1While some nations have controlled viral spread through social distancing, widespread testing, and contact tracing, many nations struggle to contain the growing number of cases and are still going through extensive community spread. Additionally, the intro of SARS-CoV-2 into low-resource settings will lead to severe and enduring effects on economic and healthcare systems. Long-term control of the pandemic will require one or more effective vaccines that can be made widely available across the globe. The primary viral target for protecting antibody-based vaccines against COVID-19 is the SARS-CoV-2 spike, a trimeric surface glycoprotein responsible for viral access.2,3Importantly, COVID-19 patients have been shown to elicit robust neutralizing antibody responses directed at the SARS-CoV-2 spike, which suggests that this antigen could be promising in the context of a protective vaccine.4,5The spike protein is produced as a single polypeptide and cleaved to form the S1 and S2 subunits, which are responsible for receptor binding (S1) and fusion with the host cell membrane (S2).3,6,7The receptor binding website (RBD) is a 25 kDa website of S1 that recognizes the SARS-CoV-2 human being receptor, angiotensin converting enzyme 2 (ACE2), and may form a functionally folded website when expressed separately from the rest of S1.810 A vast array of vaccination platforms are being employed for the development of a safe and effective SARS-CoV-2 vaccine.1119Several vaccine candidates are currently being investigated in Phase 3 medical trials including two mRNA-based vaccines and two virally vectored vaccines.2022Importantly, the mRNA vaccine candidates rely on lipidnanoparticle encapsulation and require long-term cold-chain storage (20 to 80 C),20,21leading to extensive logistical challenges for distribution and administration. Virus-based vaccines including inactivated, live-attenuated, and Rabbit Polyclonal to OR8I2 recombinant viral vaccines can create robust immune reactions, but are known to induce off-target vector-directed immune reactions23,24and can be associated with more frequent side effects and adverse events.25,26 Subunit vaccines, in which a protein antigen from your pathogen is used to elicit a protective antibody response, are an attractive option for an accessible SARS-CoV-2 vaccine for reasons including safety, manufacturing scalability, and ease of distribution to low- and middle-income nations.26Though typically less immunogenic than virus-based vaccines, the immunogenicity of subunit vaccinations can be significantly increased by formulation with adjuvants. 25It has also been shown that multivalent demonstration of antigens markedly enhances the immune response,27,28and several nanoparticle-based platforms have been utilized to multimerize antigens of interest to improve the antibody response to subunit vaccine candidates.2730Furthermore, two recent studies have shown the multivalent presentation of the SARS-CoV-2 RBD31as well while the spike ectodomain32using various multimerization platforms elicits better neutralizing antibody reactions than nonmultimerized forms of the same antigens. AAI101 One such multimerization platform,Helicobacter pyloriferritin, has been used to display antigens from influenza,33,34HIV-1,35,36and EpsteinBarr disease,30among others.37,38H. pyloriferritin self-assembles into 24-subunit particles with eight 3-fold axes of symmetry.39Fusion of a single protomer of a viral glycoprotein to the N-terminal region of anH. pyloriferritin subunit facilitates assembly of a protein nanoparticle that displays eight copies of a trimeric antigen on the surface in the 3-collapse axes.33,39Display of antigens on ferritin generally elicits a more robust neutralizing antibody response against the prospective pathogen as compared to immunization with the antigen alone.30,33,35Importantly, two influenza-functionalized ferritin vaccines have been shown to be safe and immunogenic in clinical trials (NCT03186781andNCT03814720),33,34and robust pipelines have been established for large-scale manufacturing of ferritin-based vaccines.40 Here, we fused the full-length AAI101 spike ectodomain (residues 11213) toH. pyloriferritin (denoted S-Fer;Number1) to determine the effect of antigen multimerization on elicitation of antibodies against SARS-CoV-2. Additionally, we designed a second nanoparticle.
