AUTHOR=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 TITLE=A SARS–CoV-2 Spike Receptor Binding Motif Peptide Induces Anti-Spike Antibodies in Mice andIs Recognized by COVID-19 Patients JOURNAL=Frontiers in Immunology VOLUME=13 YEAR=2022 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.879946 DOI=10.3389/fimmu.2022.879946 ISSN=1664-3224 ABSTRACT=

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 (RBM436-507) of RBD. We used ELISA to study the antibody response to each of the three antigens (S protein, its RBD domain and the RBM436-507 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.