Method of obtaining purified SARS-CoV-2 antigen for structural and immunological studies in whole-virion vaccines against coronavirus infection

BACKGROUND: Despite the large-scale development of vaccines against coronavirus infection, there is still no complete information about the antigenic structure of the SARS-CoV-2 virus particles. This article describes a method of obtaining a pure concentrated whole-virion sample that can be used in various studies. AIM: The goal is to develop an optimal method of purification of the inactivated SARS-CoV-2 virus in order to obtain a standard with parameters of purity and antigen content sufficient for structural and immunological studies. MATERIALS AND METHODS: To obtain a pure concentrated virus SARS-CoV-2 we used the sucrose density gradient ultracentrifugation. Fractions with the highest content of viral particles were evaluated based on the concentration of nucleocapsid N and glycoprotein S. The purity of the pooled fractions (the purified sample) was evaluated by the presence of impurity proteins, toxins and bovine serum albumin. RESULTS: The optimal conditions for obtaining the inactivated purified SARS-CoV-2 whole virus were determined. A standard sample of the inactivated SARS-CoV-2 virus was isolated and characterized. CONCLUSIONS: The obtained standard sample can be used in enzyme immunoassay to measure the amount of antigen in whole-virion vaccines against coronavirus infection, as well as in various structural studies of SARS-CoV-2 virus particle.