Aspergillus oryzae as a host for SARS-CoV-2 RBD and NTD expression

Abstract

The COVID-19 pandemic has increased demand for effective diagnostics, and extensive research has been conducted on the N-terminal domain (NTD) and the receptor-binding domain (RBD) of the SARS-CoV-2 spike glycoprotein, which are critical for viral binding. This study focuses on the expression of NTD and RBD in pyrG auxotrophic Aspergillus oryzae for the first time. Recombinant NTD and RBD were expressed as glucoamylase-fusion proteins and purified using metal affinity chromatography. Size-exclusion chromatography was used to confirm the correct folding and purity of the recombinant proteins. Employing an enzyme-linked immunosorbent assay, the binding ability of the fusion proteins to human anti-IgG antibodies in serum samples was evaluated. The results indicated a significant and concentration-dependent interaction, affirming the functionality of the NTD and RBD fusion proteins and establishing their efficacy in antigen-antibody interactions. This study not only elucidates the usage potential of the fusion proteins in immunoassays but also addresses the suitability of the A. oryzae expression system as a biotechnological platform to produce SARS-CoV-2 proteins. Furthermore, this study lays the foundation for scalable and cost-effective mass production of effective NTD and RBD proteins in A. oryzae, opening up a new era of COVID-19 research, vaccine development, and immunoassay design.