Antibody response to SARS-CoV-2 infection and Sputnik V vaccination

ABSTRACT

Antibodies to the SARS-CoV-2 S-protein and its RBD fragment are considered the primary immune response markers against the SARS-CoV-2. We analyzed the content of antibodies against the Sprotein and RBD of SARS-CoV-2 in the blood of employees of the SB RAS Institute of Chemical Biology and Fundamental Medicine. In 2020, some researchers were infected with COVID-19;in January- April of 2021, more than 80% of the Institute staff were vaccinated with Sputnik V. In May 2021, blood samples from 396 donors were collected. Using ELISA, we analyzed the presence of antibodies against the S- and N-proteins of the SARS-CoV-2 in the donor's blood plasma of four groups COVID-19 convalescents, vaccinated with Sputnik V (group I);patients vaccinated with Sputnik V that were not infected with COVID-19 (group II);not vaccinated COVID-19 convalescents (group III);patients that were not vaccinated and infected with SARS-CoV-2 (group IV). The blood of the group I patients had the highest amount of antibodies to the S- and N-proteins of the SARS-CoV-2. The level of antibodies against S-protein in group II was higher than in group III. Next, electrophoretically homogeneous preparations of IgG were isolated from blood plasma by affinity chromatography on Protein-GSepharose. Further, using affinity chromatography on sorbents containing immobilized recombinant SARS-CoV-2 S-protein and RBD, we isolated antibody subfractions possessing affinity to these antigens (S-IgG and RBD-IgG, respectively). The content of RBDIgG in the blood plasma of convalescent and vaccinated donors is about 1%. Antibodies of this subfraction have an affinity for other domains of the S-protein than RBD. The amount of these antibodies was less than 1%. In further studies, we plan to characterize SIgG and RBD-IgG preparations and compare them with the total pool of IgG in vaccinated and/or recovered donors.