Recombinant Expression and Purification of Novel COVID-19 Vaccine Candidate in Escherichia coli BL21 (DE3)

Abstract

ABSTRACT: COVID-19, the global pandemic, infected and killed many human beings across the world. The sudden onset and global spread of the disease necessitated the development of an efficient vaccine for mass vaccination. The present study provides the data for the expression and purification of a vaccine candidate against the SARS-CoV2 virus. The beauty of this vaccine is the employment of multiple epitopes targeting the structural and non-structural proteins of the virus, thus inhibiting the viral infection and replication. The study data showed that the recombinant vaccine candidate was sequestered into inclusion bodies in Escherichia coli (E. coli) BL21 (DE3). In order to maximize protein recovery, protein solubilization and refolding was optimized using mild chaotropic agents. Further, anion exchange (AEX) chromatography was used as a negative chromatography to remove other protein impurities and recover the protein of interest in the flow-through. The cation exchange (CEX) chromatography step provided pure protein, but the protein recovery was reduced. The final purified protein showed the presence of NSP9 and RBD when probed with antibodies against these epitopes. The study demonstrated that a multiple epitope vaccine can be successfully expressed using E. coli BL21 (DE3) as the host. However, further studies are required to prove the efficacy of the vaccine candidate.