Preparation and characterization of the recombinant norovirus VP1 surface protein S domain

Introduction. In the structure of the norovirus surface VP1, it consists of the S domain which N-terminal sequence is responsible for capsid formation, and P domain that extends beyond the capsid. Possibility of using S domain for preparing chimeric virus-like particles is shown. The aim of the work is to obtain a recombinant VP1 protein S domain and to characterize its immunogenic and antigenic properties. Materials and methods. Cloning of the sequence encoding VP1 protein S domain, modeling the structure of proteins, microbiological methods for working with E. coli cells producing recombinant proteins, polymerase chain reaction, electrophoresis of nucleic acids in an agarose gel and proteins in a polyacrylamide gel, affinity chromatography, enzyme immunoassay, electron microscopy were applied during the study. Results. A genetic construct encoding the recombinant VP1 norovirus genotype GII.4 protein S domain optimized for highly efficient expression in E. coli is obtained. E. coli Rosetta 2 cells were transformed with the genetic construct. Conditions for protein production and purification were optimized. A soluble recombinant protein reproducing norovirus VP1 protein S domain and forming virus-like particles with a diameter of 30 nm is obtained. Immunization of mice with the obtained protein caused specific antibody production including low-avidity IgM antibodies. When assessing antigenic properties, it was shown that antibodies interacting with the recombinant S domain are found in the blood samples collected from volunteers. Antibody titers, but of lower avidity, specific to the latter corresponded to those against full-length VP1. Likely, it was due to the localization of the S domain inside the viral particle. Conclusion. Antigenic and immunogenic properties of recombinant protein reproducing structure of norovirus VP1 S domain are characterized, and its ability to form virus-like particles is shown.