Yeast-Produced S1 Recombinant Protein of SARS-CoV-2

COVID-19 pandemic caused by the emerging SARS-CoV-2, being the cause of COVID-19, leads to acute respiratory syndrome and is a vital threat to global health and the economy since it was identified in late December 2019 in China. Due to the limitations and long-time of vaccine production, most countries were forced to design and produce antigens, kits, and anti-viral drugs so that they might be able to prevent deaths caused by COVID-19. This study was conducted to design and express S1 protein of SARS-CoV-2 to be used as a vaccine candidate.

Recombinant pPICZαA plasmid was replicated in Escherichia coli and the linearized plasmid was transfected into Pichia pastoris yeast as an endosomal fragment. After screening the colonies with Zeocin and confirming the presence of the gene and vector promoter inside the genome extracted from yeast, the expression of S1 protein was induced in BMMY medium with methanol.

  The S1 protein was successfully expressed in P. pastoris and the results obtained on the SDS-PAGE indicated the presence of a protein with 130 kDa molecular weight, confirmed by Western blotting.

The results of the present study showed that the yeast expression system of P. pastoris can be a suitable method to produce glycoprotein S1 as a vaccine candidate or a diagnostic antigen against COVID-19.