Lipid-nanoparticle-encapsulated mRNA vaccines induce protective memory CD8 T cells against a lethal viral infection

Area of Science:

• Immunology
• Vaccinology
• Virology

Background:

• Memory CD8 T-cells are crucial for protection against mousepox, a lethal viral disease.
• The ability of mRNA vaccines to induce protective memory CD8 T-cells remains unclear, despite their known antibody responses.

Purpose of the Study:

• To investigate if modified mRNA vaccines can induce protective memory CD8 T-cell responses.
• To evaluate the efficacy of mRNA vaccines encoding viral antigens against mousepox.

Main Methods:

• Immunization of mice with unmodified or modified mRNA encapsulated in lipid nanoparticles (LNP) encoding Ectromelia virus (ECTV) antigens.
• Assessment of CD8 T-cell responses and protection against ECTV challenge.
• Evaluation of vaccine efficacy using constructs encoding specific viral epitopes.

Main Results:

• Both unmodified and modified mRNA-LNP induced strong CD8 T-cell responses to a specific epitope.
• A single dose of modified mRNA-LNP provided significant protection against mousepox.
• Booster vaccination expanded the memory CD8 T-cell pool and conferred full protection.
• Modified mRNA-LNP vaccines encoding viral antigens protected against homologous and heterologous viral challenges.

Conclusions:

• Modified mRNA-LNP vaccines are effective in generating protective CD8 T-cell memory.
• These vaccines offer a promising strategy for developing CD8 T-cell-based vaccines against viral infections.
• Modified mRNA-LNP technology can be adapted to target specific viral epitopes for vaccine development.