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

  • Shahla Shahsavandi Razi Vaccine and Serum Research Institute, Agricultural Research Education and Extension Organization, Karaj, Iran
  • Sina Soleimani Razi Vaccine and Serum Research Institute, Agricultural Research Education and Extension Organization, Karaj, Iran
  • Majid Tebyanian Razi Vaccine and Serum Research Institute, Agricultural Research Education and Extension Organization, Karaj, Iran
  • Amir Ali Hariri Biotechnology Department, Behyaar Sanaat Sepahan Company, Isfahan, Iran
  • Ashraf Mohammadi Razi Vaccine and Serum Research Institute, Agricultural Research Education and Extension Organization, Karaj, Iran
  • Abbas Zare Mirakabadi Razi Vaccine and Serum Research Institute, Agricultural Research Education and Extension Organization, Karaj, Iran
  • Mojtaba Noofeli Razi Vaccine and Serum Research Institute, Agricultural Research Education and Extension Organization, Karaj, Iran
  • Zarrin Sharifnia Biotechnology Department, Behyaar Sanaat Sepahan Company, Isfahan, Iran
  • Mohammad Mahdi Ranjbar Razi Vaccine and Serum Research Institute, Agricultural Research Education and Extension Organization, Karaj, Iran
Keywords: SARS-CoV-2; mRNA vaccine; Receptor binding domain; Immunity

Abstract

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 mea- suring 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.

Published
2025-10-13
Section
Articles