Molecular Cloning, Expression And Purification Of A Novel COVID-19 Vaccine Candidate Against Infectious Diseases In A Culture Of Escherichia Coli

Abstract

Vaccination is one of the most effective medical interventions that has been introduced in the past few years. Vaccines are known to prevent 2.5 million deaths per year. Owing to new developing technologies, vaccines have the potential to make a huge contribution to the health of modern society by preventing many diseases of all age groups. There are many different types of vaccines based on the form of antigen used in their preparation. The present study puts emphasis on development of subunit-based vaccines against Covid-19. The subunit vaccines were constructed with two different approaches where one involved the use of Fc portion of the antibody tagged to the antigen while the other has a histidine tag for the ease of purification. The selected clones could then be transfected into mammalian cells to observe the protein expression.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. This 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 shows that the recombinant vaccine candidate is sequestered into inclusion bodies in E. coli. In order to maximize protein recovery, protein solubilization and refolding was optimized using mild chaotropic agents. Further, Anion Exchange Chromatography (AEX) was used as a negative chromatography to remove other protein impurities and recover the protein of interest in the flow-through. The Cation Exchange Chromatography (CEX) 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 shows that a multiple epitope vaccine can be expressed in E. coli but further studies are required to prove the efficacy of the vaccine candidate.