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

BACKGROUND AND

OBJECTIVES

The aim of this study was to assess the effectiveness of a new linear epitope from the N-terminal 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 protein 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.