Comprehensive evaluation of immunological activity of recombinant AD26 and AD5 expressing S protein gene of the SARS-COV-2 virus

The COVID-19 pandemic has posed a significant challenge to the global healthcare system. Vaccination is one of the most effective ways to stop and prevent the spread of the disease. Recombinant vectors based on various types of adenoviruses are the most studied platform for vaccine development. The aim of this research is to study the development of B- and T-cell immunity after administering recombinant Ad26 and Ad5 vectors that express the glycoprotein S of the SARS-CoV-2 virus in laboratory animals. Materials and methods. In this study, BALB/c and C57BL/6 mice were used. Animals were intramuscularly immunized with recombinant adenoviruses. Antigen-specific IgG antibodies were measured using an enzyme-linked immunosorbent assay. A microneutralization assay was performed to identify virus-neutralizing antibodies. Quantitative indicators of cellular immunity were measured using flow cytometry. Conclusions. The resulting recombinant adenoviruses, rAd26-S-CoV2 and rAd5-S-CoV2, were characterized according to several parameters, demonstrating their purity and functional activity. These viruses induce balanced adaptive immunity in experimental animals, as shown by the results of our study. A comparative analysis of different immunization schedules revealed the efficacy of heterologous prime-boost vaccination, providing valuable insights into the development of effective COVID-19 vaccines.