SARS-CoV-2 receptor-binding domain-based protein subunit vaccine shows promise against multiple SARS-CoV-2 variants medrxivpreprint UniMelb SARSCoV2 COVID19 Coronavirus Variants RBD
By Neha MathurAug 11 2022Reviewed by Aimee Molineux In a recent study posted to the medRxiv* pre-print server, researchers described a novel protein subunit vaccine comprising the receptor-binding domain of ancestral severe acute respiratory syndrome coronavirus 2 spike protein, dimerized with an immunoglobulin G1-fraction, crystallizable domain.
While an RBD-based protein subunit vaccine cannot completely overcome the imprinting problem, it could limit distracting the immune system to S epitopes harbored outside the RBD. Moreover, all the RBD epitopes, whether VOC-specific or shared with the ancestral strain, are more likely to induce neutralizing antibodies . Over 90% of anti-SARS-CoV-2 nAbs target the SARS-CoV-2 RBD, the small region in its S protein that facilitates binding to host cell receptor angiotensin-converting enzyme-2 .
They also developed and clinically tested a ‘Beta variant’ version of their RBD human IgG1-Fc vaccine, combined with MF59® adjuvant. Further, the team tested the ability of this modified version of the vaccine as a heterologous booster in mice previously vaccinated with two doses of a SARS-CoV-2 S protein vaccine. In this way, they evaluated its efficacy in real-world community settings, where most individuals are vaccinated with S-based vaccines.