Recombinant production and validation of immunogenic fragment from RBD of SARS-CoV-2 spike protein

Abstract

The rapid and widespread infection caused by SARS-CoV-2, a new type of coronavirus shook the whole world playing havoc with human life. Although the situation has been brought under control, the susceptibility level for its similar infection from coronavirus remains a high possibility. To safeguard from such situations the development of a reliable, economical, and high throughput method to diagnose the disease is required for preparedness in such situations. Serodiagnosis detecting antibodies produced against antigens of SARS-CoV-2 in blood samples could prove beneficial. Based on the epitope position in the molecule, an immunogenic fragment from RBD of S1 domain of spike protein of SARS-CoV-2; S1F2, was selected and expressed in Escherichia coli. Screening of S1F2 against 319 sera samples from the COVID-19 patients showed sensitivity of 41.07% and a corresponding specificity of 96.7%. Data regarding 3-D model prediction based on computational modeling was also in agreement. Solvent accessibility analysis through CPORT showed favorable orientation of the epitopic residues resulting in improved antigen-antibody interactions. This construct can be used further for producing constructs with greater sensitivity through fusion of epitopes from additional SARS-CoV-2 antigens.