RBD, a fragment (193 aa residues) . As for S-protein-based vaccines already deployed 116, it is likely that as immunity declines over time and variants arise, vaccinated individuals may be more likely to become transiently infected and transmit to . data regarding the efficacy of RBD-based vaccines are lacking. . The S protein RBD is an attractive vaccine target against COVID-19.17 To date, various vaccine candidates based on the RBD have shown efficacy in animal models against SARS-CoV, MERS-CoV, and SARS-CoV-2.4 Several RBD-based COVID-19 vaccines are being evaluated in clinical trials.4 Clinical data have been published for an RBD-based COVID-19 . by displaying multiple copies of the receptor binding domain (RBD) antigen. Based on the recent report by Tian and colleagues (2020), . These vaccines focus the immune response on the tip of the SARS-CoV-2 spike protein, called the receptor binding domain (RBD). Added value of this study. Various RBD-based protein subunit vaccines are under clinical and preclinical development, but no clinical studies have been published. ZF2001 employs technology similar to other protein-based vaccines in Phase III trials from Novavax, Vector Institute, and Medicago. Here we report the development of a recombinant protein vaccine that consists of the SARS-CoV-2 Spike RBD (Spike RBD) fused to an alpaca-derived nanobody that targets class II major histocompatibility (MHC II) complex antigens (VHH MHCII-Spike RBD).This vaccine delivers the antigen directly to class II MHC + APCs. 2 Many RBD-based Covid-19 vaccines are under development, with some having been approved . Furthermore, a subunit vaccine which is based on the receptor-binding domain (RBD) is expected to be safer than others, thus the RBD in the S protein is a more important target for vaccine development. . Quantification of neutralizing antibody levels is clearly essential for vaccine development . Based on structural and computational analysis of spike receptor-binding domain (RBD) of SARS-CoV-2, we have designed a recombinant COVID-19 vaccine (CHO cells), named NVSI-06-07, that uses a . Value added. A multidisciplinary team of researchers is the first to show that combining yeast-expression technology and a novel adjuvant formulation produces a COVID-19 vaccine candidate that is effective against SARS-COV-2. The pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome . Most train the immune system to recognize the RBD, a peptide that is the portion of the SARS-CoV-2 spike protein that binds to the ACE-2 receptor on host cell surfaces. 2 RBD is a favorable vaccine target because it focuses the immune response on interference with receptor-binding activities. However, the use of RBD in vaccines is impaired by its poor immunogenicity owing to its small molecular size. The double-blind, placebo-controlled trial evaluated a 3-dose regimen . The RBD is a part of the spike protein of SARS-CoV-2. Currently, B.1.617.2 (delta) and B.1.1.529 (omicron), the highly transmissible SARS-CoV-2 variants of concern, have brought new waves of This study is, to the best of our knowledge, the first to report . This is a randomized, observer-blind, placebo-controlled study, for evaluation of safety and immunogenicity of heterologous prime-boost immunization of recombinant COVID-19 vaccine (adenovirus type-5 vector) and RBD-based protein subunit vaccine (ZF2001) against COVID-19 in Chinese healthy population. This vaccine, which is based on a protein platform, designed to be cost-effective and given in low dose, relies on a trimer model and an immune-stimulating substance, an adjuvant, to induce a long-lasting antibody response. The current COVID-19 pandemic caused by constantly emerging SARS-CoV-2 variants still poses a threat to public health worldwide. "The RBD protein by itself is poorly immunogenic," said Dowling. It is a promising. In addition to the NIAID grant, the RBD Trimer protein vaccine study reported in this release is supported in part by . A novel vaccine against COVID-19, ZF2001 (Zifivax), from the China-based developer, Zhifei, that builds its protein subunit platform with a receptor-binding domain (RBD)-dimer demonstrated safety and efficacy in a phase 3 trial reported in the New England Journal of Medicine. The SARS-CoV-2 subunit vaccine (PreS-RBD) developed at MedUni Vienna is based on a structurally folded fusion protein consisting of two receptor binding domains (RBD) of the SARS-CoV-2 virus and . RBD-scNP is a conjugate vaccine based on ferritin nanoparticles, directed against RBD (an important part of the S-protein) of SARS-CoV-2. CORBEVAX is India's first indigenously developed receptor-binding domain (RBD) protein sub-unit vaccine against Covid-19. . Overall, this study identifies RBD as a key antigen to design effective vaccines against SARS-CoV-2, indicating great potential of RBD-based mRNA vaccine for mitigation of the COVID-19 pandemic and possible SARS-related epidemics in the future. These findings suggest that RBD contains the major neutralizing epitopes in the S protein and is an ideal SARS vaccine candidate because RBD contains the receptor-binding site, . Together, these findings suggest that recombinant protein-based vaccines based on the RBD warrant further development to prevent SARS, COVID-19, or other coronaviruses of pandemic potential. For that vaccine, the researchers used an RBD fragment that was based on the sequence of the original SARS-CoV-2 strain that emerged in late 2019. Results We reasoned that an improved RBD variant for vaccine candidates should exhibit both improved quality attributes relevant for manufacturing (increased titers, reduced aggregation) and immunogenicity relative . The receptor-binding domain (RBD) of the virus's spike protein engages the primary host cell receptor, angiotensin-converting enzyme 2 (ACE2), for both SARS-CoV-2 and SARS-CoV-1. The wide 19, availability of yeast expression technology for hepatitis B vaccines in low- and middle-income nations highlights a significant advantage for rapid manufacture of yeast-based SARS-CoV-2 vaccines, helping meet the need for inexpensive and accessible COVID-19 vaccines (8). positions. In addition, RBD tends to establish a monomer-dimer . Most protein-based vaccines train the immune system to recognise the RBD, a portion of the SARS-CoV-2 spike . Animal tests have shown that the vaccine leads to the . CpG-adjuvanted RBD-based subunit vaccine candidates in pre- clinical and clinical development but there has also been a recent emergency use authorization in India of an RBD-based vaccine containing both aluminum salt and CpG adjuvants.32-44 In general, adjuvanted RBD-based candidates have been reported . In addition, as the RBD preferentially focuses the immune response to potent and recently recognized cross-protective determinants, this domain may be central to the development of future pan . And neither vaccine requires extreme cold chain storage, which makes . That vaccine has been tested in a phase 1 clinical trial in Australia. Early in the pandemic, studies in animals suggested that this protein fragment alone would not produce a strong immune response, so to make it more immunogenic, the team decided to display many copies of the protein on a virus-like particle. Received any prophylactic or therapeutic vaccine, or licensed or unlicensed vaccine, device, or blood product, within 4 weeks of first vaccination or 5 half-lives (whichever is longer), or anticipate to do so in the follow-up period . This type of assay, that is RBD-binding antibody measurements, have been used in the Phase 1-2 studies of the RNA-based vaccines , and has been shown to correlate with direct virus neutralizing assays [31, 38], not available for larger scale studies. To maximize a vaccine's potential to prevent COVID-19, the following key criteria were evaluated in the selection of the final vaccine candidate and dose level: - - - Acceptable safety and reactogenicity SARSoV-C -2 neutralizing titers at or above a human convalescent serum panel (HCS) Strong T Two studies based on phase 3 clinical trials published yesterday in the New England Journal of Medicine show promising results for two novel COVID-19 vaccine platformsa plant-based coronavirus-like particle vaccine, and a receptor-binding domain (RBD)-dimer-based vaccine. The double-blind, placebo-controlled trial evaluated a 3-dose regimen . "That's why people have used the full spike protein, which is harder to produce at scale. The vaccine was well tolerated and immunogenic. Here, we sequentially immunized mice with a SARS-CoV-2 wild-type inactivated vaccine and a heterologous mutant RBD vaccine, and then evaluated their neutralizing . The two candidates are: . . . The strategy of developing RBD-based mRNA COVID-19 vaccine, as described herein, can also be applied to develop vaccines against other emerging and reemerging coronavirus diseases in the future.. Recent studies have found that putting multiple copies of the RBD on nanoparticles enhances the immune response. . It includes methods for transfection and expression of RBD protein in 293T cells, immunization of mice with RBD and detection of neutralization activity of mouse sera using an established SARS pseudovirus neutralization assay. There is growing interest, therefore, in the utility of RBD-based vaccine boosters to provide immunity against emerging variants of SARS-CoV-2 that may escape antibody responses induced by . The receptor-binding domain (RBD). However, not all of these vaccines elicit both antibody and T cell responses, both of which are thought to be important for longer-lasting immunity. While the SII's Covovax is a nanoparticle-based vaccine, Hyderabad-based firm Biological E's Corbevax is an RBD protein subunit vaccine. As per the Union Health Minister, "Corbevax vaccine is India's 1st indigenously developed RBD protein sub-unit vaccine against #COVID19, Made by Hyderabad-based firm Biological-E. It's a hat-trick! In this review, we focus on the neutralizing antibodies targeting the RBD as well as the vaccine based on the RBD under current development. Vaccines Based on Fragments Containing Neutralizing Epitopes. A Study to Evaluate Safety, Tolerability, and Reactogenicity of an RBD-Fc-based Vaccine to Prevent COVID-19. Using a method called deep mutational scanning, the Seattle group's previous study mapped out all possible mutations in the RBD that would change the ability of the virus to bind ACE2 and/or for RBD-directed antibodies to strike their targets. With the adjuvants we selected, we were able to make an RBD-based protein vaccine as . The RBD-dimer significantly increases . The epitopes of RBD can be categorized into several major classes based on cluster analysis of available neutralizing antibody-RBD complex structures 29,30,31,32,33. A safe, efficacious and deployable vaccine is urgently needed to control COVID-19 pandemic. It combines the RBD with two vaccine adjuvants: molecules that boost the immune response. Here, we designed a lipid nanoparticle-encapsulated, nucleoside-unmodified mRNA (mRNA-LNP) vaccine encoding the trimerized receptor-binding domain (RBD trimer) and showed its robust capability in inducing broad and protective immune responses against wild-type and major variants of concern (VOCs) in the mouse model of SARS-CoV-2 infection. They could also address some of the hesitancy around vaccines based on newer technologies," Love says. It is shown that immunization of mice with a candidate subunit vaccine consisting of SARS-CoV-2 RBD and Fc fragment of human IgG, as an immunopotentiator, elicited high titer of RBD-specific antibodies with robust neutralizing activity against both pseudotyped and live Sars-Cov-2 infections. In contrast, both Boston Children's vaccines use just a portion of the spike, namely the receptor-binding domain or RBD. Given the antigen of S-268019-b is based on full-length S protein and anti-RBD antibodies are well-correlated with neutralizing antibody titer, RBD mutations may have been responsible for the reduced . Specifically, antibodies elicited by the mRNA vaccine were more focused to the RBD compared to antibodies elicited by an infection, which more often targeted other portions of the spike protein. The RBD enables the virus to enter and infect cells in the body and elicits over 90 per cent of neutralising antibodies (antibodies that can block the virus) following SARS-CoV-2 infection. Immunization of both young and aged mice with two doses of VHH MHCII-Spike RBD . @article{osti_1808237, title = {A yeast-expressed RBD-based SARS-CoV-2 vaccine formulated with 3M-052-alum adjuvant promotes protective efficacy in non-human primates}, author = {Pino, Maria and Abid, Talha and Pereira Ribeiro, Susan and Edara, Venkata Viswanadh and Floyd, Katharine and Smith, Justin C . RBD-based vaccine against SARS-CoV in mice (20). "The RBD is a key SARS-CoV-2 vaccine target, but the RBD protein by itself is poorly immunogenic," says David Dowling, Ph.D., co-senior author on the paper with Ofer Levy, MD, Ph.D., director of . Therefore, RBD serves as an important antigen for the development of COVID-19 subunit vaccines, and numerous researchers revealed the great potential of RBD-based subunit vaccines. CpG-adjuvanted RBD-based subunit vaccine candidates in pre- clinical and clinical development but there has also been a recent emergency use authorization in India of an RBD-based vaccine containing both aluminum salt and CpG adjuvants.32-44 In general, adjuvanted RBD-based candidates have been reported . Our study provides a proof-of-principle of utilizing a plant transient expression system for the rapid production of other . The mRNA vaccines (Pfizer BNT162b2 or Moderna mRNA-1273) efficiently primed memory B cells specific for full-length S-protein and RBD, and these were detectable in all subjects after the second. The team also added a compound to the vaccine called an adjuvant that is designed to . Although they often need additives (adjuvants) to make the immune response to . Existing COVID-19 vaccines are based on the full SARS-CoV-2 spike protein.