Engineering the ADDomer Nanoparticle Vaccine Scaffold for Improved Assembly and Enhanced Stability

Area of Science:

• Biotechnology
• Vaccinology
• Structural Biology

Background:

• Virus-like particles (VLPs) are advanced vaccine platforms due to their repetitive antigen presentation, mimicking pathogen patterns for potent immune responses.
• The ADDomer, a synthetic dodecahedral VLP from adenovirus penton base protein, offers antigen insertion but suffers from incomplete assembly and pre-existing immunity concerns.

Purpose of the Study:

• To engineer enhanced ADDomer scaffolds with improved robustness, stability, and reduced susceptibility to pre-existing immunity for vaccine applications.
• To develop strategies for creating more reliable and broadly applicable virus-like particle (VLP) vaccine platforms.

Main Methods:

• Developed a Chimpanzee adenovirus Y25-based ADDomer (CHIMPSELS) and introduced a point mutation for dodecahedron integrity.
• Incorporated intersubunit disulfide bonds to reinforce particle assembly and stability.
• Utilized high-resolution cryo-electron microscopy, differential scanning fluorimetry, and dynamic light scattering to characterize particle structure and stability.

Main Results:

• Successfully created intact dodecahedral particles with enhanced structural integrity and thermal stability.
• Disulfide bonds stabilized distinct conformations and improved particle assembly.
• Modified scaffolds maintained structural integrity and displayed validated immunogenic epitopes, including SARS-CoV-2 and Chikungunya peptides.

Conclusions:

• The engineered ADDomer presents a versatile, thermostable VLP platform with enhanced particle integrity and modular epitope presentation.
• This improved VLP platform demonstrates reduced susceptibility to pre-existing immunity, making it suitable for broader vaccine development.
• The applied engineering strategies offer a scalable approach for enhancing protein-based VLP vaccine performance.