SARS-CoV-2 mRNA vaccine candidate encoding RBD chimera of Delta and Omicron variants: immunogenic potential and validation.

BACKGROUND AND

OBJECTIVES

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has presented a challenging issue for global health in the 21st century. Frequent mutations in viral genomes have diminished the effectiveness of current vaccines against new variants. Messenger RNA (mRNA) vaccine is a promising platform for eliciting a robust T cell immune response.

MATERIALS AND

METHODS

We evaluated the uptake of mRNA-LNPs into human monocyte-derived dendritic cells by measuring the intensity of enhanced eGFP expression in the transfected cells. Next, we assessed the effect of mRNA-LNPs on immune response induction in mice following a prime-boost immunization strategy, along with analyzing cytokine release. The safety of the vaccine candidate was examined through pyrogenicity and toxicity assays.

RESULTS

Upon intramuscular injection of mice, potent antibodies specific to viral S protein, robust Th1-biased cell-mediated immunity, and enhanced IFN-γ expression were induced. These observations indicate that mRNA-LNP was taken up and that it migrated to the lymph nodes. Furthermore, the vaccine candidate did not cause inflammation or local reactions after injection, as confirmed by biochemical, hematological, and histopathological examinations.

CONCLUSION

Because of its ability to target immune cells, the mRNA vaccine candidate can potentially improve immune responses against circulating or emerging variants.