Identification of Immunodominant Epitopes on Nucleocapsid and Spike Proteins of the Sars-Cov-2 in Iranian Covid-19 Patients Publisher Pubmed



Maghsood F¹ ; Shokri MR¹ ; Jedditehrani M² ; Rahvar MT³ ; Ghaderi A⁴ ; Salimi V⁵ ; Kardar GA⁶ ; Zarnani AH¹ ; Amiri MM¹ ; Shokri F¹
Source: Pathogens and Disease Published:2022

Abstract

Given the emergence of SARS-CoV-2 virus as a life-threatening pandemic, identification of immunodominant epitopes of the viral structural proteins, particularly the nucleocapsid (NP) protein and receptor-binding domain (RBD) of spike protein, is important to determine targets for immunotherapy and diagnosis. In this study, epitope screening was performed using a panel of overlapping peptides spanning the entire sequences of the RBD and NP proteins of SARS-CoV-2 in the sera from 66 COVID-19 patients and 23 healthy subjects by enzyme-linked immunosorbent assay (ELISA). Our results showed that while reactivity of patients' sera with reduced recombinant RBD protein was significantly lower than the native form of RBD (P < 0.001), no significant differences were observed for reactivity of patients' sera with reduced and non-reduced NP protein. Pepscan analysis revealed weak to moderate reactivity towards different RBD peptide pools, which was more focused on peptides encompassing amino acids (aa) 181-223 of RBD. NP peptides, however, displayed strong reactivity with a single peptide covering aa 151-170. These findings were confirmed by peptide depletion experiments using both ELISA and western blotting. Altogether, our data suggest involvement of mostly conformational disulfide bond-dependent immunodominant epitopes in RBD-specific antibody response, while the IgG response to NP is dominated by linear epitopes. Identification of dominant immunogenic epitopes in NP and RBD of SARS-CoV-2 could provide important information for the development of passive and active immunotherapy as well as diagnostic tools for the control of COVID-19 infection. © 2022 The Author(s) 2022. Published by Oxford University Press on behalf of FEMS.