Jet Injection of Naked mRNA Encoding the RBD of the SARS-CoV-2 Spike Protein Induces a High Level of a Specific Immune Response in Mice.

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.

Removal of Double-Stranded RNA Contaminants During Template-Directed Synthesis of mRNA.

The removal of double-stranded RNA (dsRNA) contaminants during in vitro mRNA synthesis is one of the technological problems to be solved. Apparently, these contaminants are the result of the T7 RNA polymerase side activity. In this study, we used a modified method of mRNA purification based on the selective binding of dsRNA to cellulose in ethanol-containing buffer.

Delivery of Experimental mRNA Vaccine Encoding the RBD of SARS-CoV-2 by Jet Injection.

We studied a needle-free jet injection delivery of an experimental mRNA vaccine encoding the receptor-binding domain of the SARS-CoV-2 S protein (mRNA-RBD). Immunization of BALB/c mice with mRNA-RBD by a needle-free jet injector induced high levels of antibodies with virus-neutralizing activity and a virus-specific T-cell response. The immune response was low in the group of mice that received intramuscular injection of mRNA-RBD.

Immunogenic and Protective Properties of Recombinant Hemagglutinin of Influenza A (H5N8) Virus.

In this study, we characterized recombinant hemagglutinin (HA) of influenza A (H5N8) virus produced in Chinese hamster ovary cells (CHO-K1s). Immunochemical analysis showed that the recombinant hemagglutinin was recognized by the serum of ferrets infected with influenza A (H5N8) virus, indicating that its antigenic properties were retained. Two groups of Balb/c mice were immunized with intramuscular injection of recombinant hemagglutinin or propiolactone inactivated A/Astrakhan/3212/2020 (H5N8) influenza virus.

DNA Vaccine Encoding the Artificial T-Cell Polyepitope Immunogen of Tick-Borne Encephalitis Virus.

A promising approach to the development of new means for preventing infection caused by tick-borne encephalitis virus can be DNA vaccines encoding polyepitope T-cell immunogens. A DNA vaccine pVAX-AG4-ub encoding an artificial polyepitope immunogen that includes cytotoxic and T-helper epitopes from the NS1, NS3, NS5, and E proteins of the tick-borne encephalitis virus has been obtained. The developed construct ensured the synthesis of the corresponding mRNAs in transfected eukaryotic cells.

The use of electroporation to deliver DNA-based vaccines.

Introduction: Nucleic acids represent a promising platform for creating vaccines. One disadvantage of this approach is its relatively low immunogenicity. Electroporation (EP) is an effective way to increase the DNA vaccines immunogenicity.

Artificial COVID-19 T-Cell Immunogen.

An artificial T-cell immunogen consisting of conserved fragments of different proteins of the SARS-CoV-2 virus and its immunogenic properties were studied in BALB/c mice. To create a T-cell immunogen, we used an approach based on the design of artificial antigens that combine many epitopes from the main proteins of the SARS-CoV-2 virus in the one molecule. The gene of the engineered immunogen protein was cloned as part of the pVAX1 plasmid in two versions: with an N-terminal ubiquitin and without it.

Dendrimer-Mediated Delivery of DNA and RNA Vaccines.

DNA and RNA vaccines (nucleic acid-based vaccines) are a promising platform for vaccine development. The first mRNA vaccines (Moderna and Pfizer/BioNTech) were approved in 2020, and a DNA vaccine (Zydus Cadila, India), in 2021. They display unique benefits in the current COVID-19 pandemic.

Optimization of In Vivo Electroporation Conditions and Delivery of DNA Vaccine Encoding SARS-CoV-2 RBD Using the Determined Protocol.

Vaccination against SARS-CoV-2 and other viral infections requires safe, effective, and inexpensive vaccines that can be rapidly developed. DNA vaccines are candidates that meet these criteria, but one of their drawbacks is their relatively weak immunogenicity. Electroporation (EP) is an effective way to enhance the immunogenicity of DNA vaccines, but because of the different configurations of the devices that are used for EP, it is necessary to carefully select the conditions of the procedure, including characteristics such as voltage, current strength, number of pulses, etc.