Selective reversed-phase high-performance liquid chromatography method for the determination of intact SARS-CoV-2 spike protein

Protein-based vaccines are playing an increasingly important role in the COVID-19 pandemic. As late-stage clinical data are finalized and released, the number of protein-based vaccines expected to enter the market will increase significantly. Most protein-based COVID-19 vaccines are based on the SARS-CoV-2 spike protein (S-protein), which plays a major role in viral attachment to human cells and infection. As a result, in order to develop and manufacture quality vaccines consistently, it is imperative to have access to selective and efficient methods for the bioanalytical assessment of S-protein. In this study, samples of recombinant S-protein (hexS-protein) and commercial S-protein were used to develop a selective reversed-phase HPLC (RP-HPLC) method that enabled elution of the intact S-protein monomer as a single peak on a wide pore, C8-bonded chromatographic column. The S-protein subunits, S1 and S2 subunits, were clearly separated from intact S-protein and identified. The results of this study set the foundation for reversed-phase HPLC method development and analysis for selective and efficient separation of S-protein monomer from its subunits.