A single extracellular vesicle-based platform supporting both RBD protein and mRNA vaccination against SARS-CoV-2.

Area of Science:

• Biotechnology
• Immunology
• Vaccinology

Background:

• The COVID-19 pandemic highlighted the need for advanced vaccine platforms.
• Existing platforms require improvements in safety, efficacy, and flexibility.
• Extracellular vesicles (EVs) show promise as vaccine delivery vehicles.

Purpose of the Study:

• To develop a modular EV-based vaccine system using a novel post-loading technology.
• To evaluate the efficiency of antigen encapsulation (protein and mRNA) into EVs.
• To assess the immunogenicity and stability of the engineered EV vaccines.

Main Methods:

• Engineered extracellular vesicles (EVs) using Shock Wave Extracellular Vesicle Engineering Technology (SWEET).
• Loaded EVs with SARS-CoV-2 receptor-binding domain (RBD) protein and mRNA.
• Assessed antigen encapsulation efficiency and EV integrity.
• Evaluated humoral and cellular immune responses in murine models.
• Tested vaccine immunogenicity after lyophilization and cold storage.

Main Results:

• Achieved high-efficiency encapsulation of both RBD protein (~69%) and mRNA (~75%) into EVs.
• EV vaccines induced potent, adjuvant-free humoral and balanced Th1/Th2 cellular immunity in mice.
• Immune responses were comparable or superior to alum-adjuvanted vaccines.
• Lyophilized EV vaccines maintained immunogenicity after 7 days at 4°C.
• Demonstrated a single EV platform for independent delivery of protein or mRNA vaccines.

Conclusions:

• The SWEET platform enables efficient, modular EV-based vaccine development for protein or mRNA antigens.
• These EV vaccines elicit robust, adjuvant-free immune responses and offer improved stability for distribution.
• This technology represents a promising next-generation platform for vaccines and drug delivery.