A Study on Self-Amplifying RNA Vaccine for Prevention of Enterovirus D68 Infection and Disease in Clinical Models

1. Background

In recent years, rapid response to emerging infectious diseases and vaccine development have received much attention. Particularly, the emergence of the novel coronavirus (SARS-CoV-2) has led to rapid advancement in RNA vaccine technology research. However, most current RNA vaccines target enveloped viruses, and the path to combat non-enveloped viruses remains unclear. Enterovirus D68 (EV-D68) is a non-enveloped virus that has caused a series of severe respiratory infections and neurological symptoms in recent years, especially the rising trend of acute flaccid myelitis (AFM), making it a focus of research. Therefore, this study aims to explore a method of preventing EV-D68 infection and disease based on a self-amplifying RNA (RepRNA) vaccine.

2. Source

This paper was completed by Warner et al., from institutions including HDT Bio, University of North Carolina at Chapel Hill, Rutgers, State University of New Jersey, and NIH. The paper was published in “Science Translational Medicine” on August 7, 2024.

3. Research Process

3.1 Research Subjects and Procedures

This study mainly conducted experiments through animal models (mice and non-human primates) to evaluate the neutralizing antibody response of different vaccine candidates to EV-D68 and their effectiveness in preventing infection and disease. The research process is divided into the following steps:

3.1.1 Self-amplifying RNA Construction

A series of RepRNA vaccine candidates were designed based on the B1 subgroup of EV-D68, optimizing the co-expression of P1 and 3CD polyproteins. By comparing two different co-expression methods (IRES-mediated P1 and 3CD co-expression versus T2A peptide sequence-mediated co-expression), the former was determined to be more effective.

3.1.2 Mouse Immunization Experiments

6-8 week old female C57BL/6 mice were used to test vaccine candidates. The RepRNA vaccine formulated with LION (Lipid Inorganic Nanoparticle) was administered through intramuscular injection, and the production of neutralizing antibodies and their protective effect were evaluated through immunization and challenge. Results showed that only the P1IRES-3CD RepRNA vaccine containing 3CD could induce significant neutralizing antibody responses and prevent viral spread in the lungs.

3.2 Data Analysis and Results

3.2.1 Characterization of Antigen Diversity

To further explore the antigenicity of the RepRNA vaccine, mice were vaccinated with candidate vaccines targeting different EV-D68 subtypes. The study found that the B1 subtype vaccine performed best in inducing broad neutralizing antibody responses, with slightly less neutralizing responses to A1 and C subtype vaccines.

3.2.2 Long-term and Cross-subtype Immune Protection

In the experiment, different doses of B3-RepRNA vaccine were tested for long-term and cross-subtype protection against B3 and B1 subtypes. Results showed that high-dose vaccines could provide not only long-term protection but also protection against heterotypic viruses to some extent.

3.3 Conclusions and Significance

The research results show that RepRNA vaccines can not only induce strong neutralizing antibody responses in animal models but also provide protection against EV-D68 infection in both short and long term. In addition, the RepRNA vaccine formulated with LION not only provides superior viral control in the lower respiratory tract but also demonstrates good local infection control, which is important for reducing viral transmission.

4. Highlights and Application Value

4.1 Important Findings

A major highlight of this study is that the RepRNA vaccine formulated with LION demonstrated significant immune effects in animal models, particularly in protecting against upper respiratory tract infections. This finding has great significance for preventing the spread of respiratory viruses.

4.2 Novelty

By co-expressing antigens P1 and 3CD, the polyprotein gained the ability to induce neutralizing antibodies, which is an important innovation in the field of RNA vaccines. Compared to traditional vaccine methods, this study demonstrates the enormous potential of RNA technology in rapidly responding to emerging viruses.

4.3 Research Significance

This study not only provides a new method for preventing and controlling EV-D68 but also offers important references for vaccine development against other non-enveloped viruses. It can be foreseen that RNA vaccine technology will play an important role in combating various infectious diseases in the future.

5. Other Valuable Information

5.1 Data Reproducibility

To ensure the reliability of research results, the research team verified the reproducibility of the data through multiple experiments and detailed the specific operational steps of each experiment.

5.2 Future Research Directions

With the successful application of this technology in animal models, future research will further explore its potential application in humans, including dose optimization, safety assessment, and other aspects, further promoting the transition of EV-D68 vaccines from laboratory to clinical application.

This study provides strong scientific evidence and technical routes for the application of RNA vaccines in non-enveloped viruses. Its broad neutralizing antibody response and infection prevention effects have opened a new path for combating multiple infectious diseases.