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Updated: May 5, 2026
Protocol for Recombinant RBD-based SARS Vaccines: Protein Preparation, Animal Vaccination and Neutralization Detection
Published on: May 2, 2011
Jet Injection of Naked mRNA Encoding the RBD of the SARS-CoV-2 Spike Protein Induces a High Level of a Specific
Denis N Kisakov1, Larisa I Karpenko1, Lyubov A Kisakova1
1State Research Center of Virology and Biotechnology "Vector", Rospotrebnadzor, World-Class Genomic Research Center for Biological Safety and Technological Independence, Federal Scientific and Technical Program on the Development of Genetic Technologies, 630559 Koltsovo, Russia.
Abstract:
Background: Although mRNA vaccines encapsulated in lipid nanoparticles (LNPs) have demonstrated a safety profile with minimal serious adverse events in clinical trials, there is opportunity to further reduce mRNA reactogenicity. The development of naked mRNA vaccines could improve vaccine tolerability. Naked nucleic acid delivery using the jet injection method may be a solution. Methods: In the first part of the study, the optimal conditions providing low traumatization and high expression of the model mRNA-GFP molecule in the tissues of laboratory animals were determined. Then, we used the selected protocol to immunize BALB/c mice with mRNA-RBD encoding the SARS-CoV-2 receptor-binding domain (RBD). It was demonstrated that mice vaccinated with naked mRNA-RBD developed a high level of specific antibodies with virus-neutralizing activity. The vaccine also induced a strong RBD-specific T-cell response and reduced the viral load in the lungs of the animals after infection with the SARS-CoV-2 virus. The level of immune response in mice immunized with mRNA-RBD using a spring-loaded jet injector was comparable to that in animals immunized with mRNA-RBD encapsulated in LNPs. Results: In this study, the efficacy of an inexpensive, simple, and safe method of mRNA delivery using a spring-loaded jet injector was evaluated and validated. Conclusions: Our findings suggest that the jet injection method may be a possible alternative to LNPs for delivering mRNA vaccines against SARS-CoV-2 infection.
Insights
Naked messenger RNA (mRNA) vaccines delivered via jet injection show comparable efficacy to lipid nanoparticle (LNP) encapsulated vaccines. This simple, safe method offers a promising alternative for reducing vaccine reactogenicity and improving tolerability.
Area of Science:
- Biotechnology
- Immunology
- Vaccinology
Background:
- Current mRNA vaccines use lipid nanoparticles (LNPs), which have a good safety profile but can cause reactogenicity.
- Developing naked mRNA vaccines could enhance vaccine tolerability.
- Jet injection presents a potential method for delivering naked nucleic acids.
Purpose of the Study:
- To evaluate the efficacy of naked mRNA vaccines delivered via jet injection.
- To compare the immunogenicity and protective effects of jet-injected naked mRNA-RBD with LNP-encapsulated mRNA-RBD.
- To assess the safety and simplicity of the jet injection method for mRNA delivery.
Main Methods:
- Optimized conditions for naked mRNA-GFP delivery in animal models to minimize tissue trauma and maximize expression.
- Immunization of BALB/c mice with naked mRNA encoding the SARS-CoV-2 receptor-binding domain (RBD) using a spring-loaded jet injector.
- Assessment of antibody levels, virus-neutralizing activity, T-cell response, and viral load in lungs post-challenge.
Main Results:
- Jet injection of naked mRNA-RBD elicited high levels of specific antibodies with virus-neutralizing activity.
- A robust RBD-specific T-cell response was observed in vaccinated mice.
- Jet-injected naked mRNA-RBD demonstrated comparable immunogenicity to LNP-encapsulated mRNA-RBD and reduced viral load in lungs after SARS-CoV-2 infection.
Conclusions:
- Jet injection is an effective, inexpensive, simple, and safe method for delivering naked mRNA vaccines.
- This method shows potential as an alternative to LNPs for mRNA vaccine delivery against SARS-CoV-2.
- Further development of jet injection could improve mRNA vaccine tolerability and accessibility.
