A SARS–CoV-2 Spike Receptor Binding Motif Peptide Induces Anti-Spike Antibodies in Mice andIs Recognized by COVID-19 Patients

• Published in: Frontiers in immunology Vol. 13; p. 879946
• Main Authors: Pratesi, Federico, Errante, Fosca, Pacini, Lorenzo, Peña-Moreno, Irina Charlot, Quiceno, Sebastian, Carotenuto, Alfonso, Balam, Saidou, Konaté, Drissa, Diakité, Mahamadou M., Arévalo-Herrera, Myriam, Kajava, Andrey V., Rovero, Paolo, Corradin, Giampietro, Migliorini, Paola, Papini, Anna M., Herrera, Sócrates
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers 26.05.2022; Frontiers Media S.A
• Subjects: Animals; Antibodies, Viral; COVID-19; Emerging diseases; Human health and pathology; Humans; immunized animals; Immunology; Infectious diseases; Life Sciences; Mice; neutralizing Abs; Peptides; receptor binding motif; SARS-CoV-2; spike (S) protein; Spike Glycoprotein, Coronavirus; COVID-19; SARS-CoV-2; receptor binding motif; neutralizing Abs; spike (S) protein; immunized animals
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2022.879946

The currently devastating pandemic of severe acute respiratory syndrome known as coronavirus disease 2019 or COVID-19 is caused by the coronavirus SARS-CoV-2. Both the virus and the disease have been extensively studied worldwide. A trimeric spike (S) protein expressed on the virus outer bilayer leaflet has been identified as a ligand that allows the virus to penetrate human host cells and cause infection. Its receptor-binding domain (RBD) interacts with the angiotensin-converting enzyme 2 (ACE2), the host-cell viral receptor, and is, therefore, the subject of intense research for the development of virus control means, particularly vaccines. In this work, we search for smaller fragments of the S protein able to elicit virus-neutralizing antibodies, suitable for production by peptide synthesis technology. Based on the analysis of available data, we selected a 72 aa long receptor binding motif (RBM 436-507 ) of RBD. We used ELISA to study the antibody response to each of the three antigens (S protein, its RBD domain and the RBM 436-507 synthetic peptide) in humans exposed to the infection and in immunized mice. The seroreactivity analysis showed that anti-RBM antibodies are produced in COVID-19 patients and immunized mice and may exert neutralizing function, although with a frequency lower than anti-S and -RBD. These results provide a basis for further studies towards the development of vaccines or treatments focused on specific regions of the S virus protein, which can benefit from the absence of folding problems, conformational constraints and other advantages of the peptide synthesis production.