Expression and Characterization of SARS-CoV-2 RBD Recovered from Inclusion Bodies in E. coli by Using Mild...

The next generation of jabs to restraint SARS-CoV-2 will be based on protein antigens. Fast, cost effective and easy to scale up expression of untagged protein is important to meet the global vaccine and diagnostic demand in a short time. Complex processes incurs heavy costs and limit the access of many vaccines to underdeveloped nations which is home to the majority of the world's population. In this study, the receptor binding domain (RBD) of SARS-CoV-2 without any tag was expressed in E. coli expression system as inclusion body aggregates. RBD of SARS-CoV-2 was purified to homogeneity by extensive washing and use of mild solubilization strategy without the requirement of multiple chromatographic steps. About 40 mg of RBD was recovered per Liter shake flask culture. Purified RBD was a predominant beta sheet structure with some alpha helix. RBD was stable at 37 °C for one month and resisted any major structural changes. Further, the RBD was formulated into polymer nanoparticles and showed improvement of immunogenicity. Thermally stable protein-based vaccine production from E. coli system can be helpful in overcoming the acute vaccine shortage by rapid production, bringing down cost and increasing the access to resource limited settings.

The online version contains supplementary material available at 10.1007/s12088-025-01499-4.