Diagnostic potential of new linear epitopes derived from the N-terminal domain of the SARS-CoV-2 Glycoprotein S

  • Sajjad Bahman Department of Medical Biotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
  • Safar Farajnia Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
  • Effat Alizadeh Department of Medical Biotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
  • Farzin Seirafi Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
  • Hojjatollah Nozad Charoudeh Stem Cell Research Center and Department Applied Cell Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
  • Mohammad Kazem Hosseini Department Molecular Biology and Genetics, Faculty of Sciences, Istanbul University, Istanbul, Turkey
Keywords: COVID-19; Epitopes; Enzyme-linked immunosorbent assay; Protein purification; Serologic diagnosis

Abstract

Background and Objectives: The aim of this study was to assess the effectiveness of a new linear epitope from the N-ter minal domain (NTD) of the SARS-CoV-2 S protein in the diagnosis of COVID-19.

Materials and Methods: Serum samples from patients were confirmed to have COVID-19 by means of RT-PCR. The linear epitope sequence of the NTD was amplified by RT-PCR, inserted into an expression vector, and produced in Escherichi coli (DE3) pLysS. Subsequently, the recombinant proteins were purified and refolded. The interaction between the purified pro- tein and the antibodies in COVID-19 patient sera was evaluated using ELISA.

Results: Sequencing verified that the N-terminal linear epitope was successfully cloned into the PET-22b vector with a 6His-tag at the C-terminal end. The presence of a 25 kDa band on SDS-PAGE indicated the successful purification of the recombinant protein using Ni-NTA chromatography. The results of ELISA showed that the NTD linear epitope had strong sensitivity (88%) and specificity (96%) for identifying viral infection in COVID-19 patients' blood samples.

Conclusion: The findings of this study demonstrated that the NTD linear epitopes of the SARS-CoV-2 spike protein exhibit significant sensitivity and specificity for the diagnosis of COVID-19 infection using serological techniques. However, further evaluations involving larger sample sizes across diverse ethnic populations is essential.

Published
2025-06-01
Section
Articles