This work highlights the importance of a target gene sequence optimization in vaccine development.

THE PURPOSE OF THE STUDY

Was to compare the immunogenicity of recombinant adenoviruses expressing the S protein gene of the SARS-CoV-2 virus variant Omicron (BA.5.3.1) with an optimized nucleotide sequence (Ad5-S-BA5opt) or non-optimized (Ad5-S-BA5).

MATERIAL AND METHODS

Recombinant adenoviruses were grown on HEK293 cell culture; purification was carried out by ultracentrifugation in a stepwise density gradient of CsCl. The resulting adenovirus samples were characterized by authenticity (by real-time PCR (RT-PCR) and immunoblotting), the number of viral particles (using spectrophotometry) and infectious titer (using the end-point dilution (TCD₅₀) method). The titer of RBD-specific IgG antibodies in an animal model was assessed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Based on the results of studies in an animal model, a vector expressing the optimized gene (Ad5-S-BA5opt) led to the formation of higher levels of IgG-specific antibodies compared to a similar vector containing the wild-type protein gene. Particularly interesting is the fact that an approach aimed solely at optimizing the sequence of the target gene, and not other components of the vector, can make significant changes in the immunogenicity of the vector.

CONCLUSION

The obtained results are important for the development of new, more effective strategies for creating vaccines and gene therapy drugs. Optimization of the nucleotide sequence can lead to an improved mRNA stability and a significant increase in the expression of the target gene, and as a result, a significant increase in the protective properties of the candidate drug. This method can be assumed to become promising for the development of vaccines against viruses containing low-immunogenic antigens.