Heterologous Prime-Boost with Immunologically Orthogonal Protein Nanoparticles for Peptide Immunofocusing

Area of Science:

• Nanotechnology
• Immunology
• Virology

Background:

• Protein nanoparticles are effective vaccine platforms for antigen presentation.
• Encapsulins are self-assembling protein nanocompartments with inherent immunogenic properties.
• RNA packaging within encapsulins enhances their immunogenicity and self-adjuvanting capabilities.

Purpose of the Study:

• To engineer encapsulins for presenting SARS-CoV-2 receptor binding domain (RBD) peptides.
• To evaluate the immunogenicity of engineered encapsulins.
• To investigate the use of orthogonal nanoparticles for fine-tuning epitope-focused antibody responses.

Main Methods:

• Genetic incorporation of a SARS-CoV-2 RBD peptide into encapsulin coat protein.
• Characterization of engineered nanoparticles using cryogenic electron microscopy.
• Heterologous prime/boost vaccination strategies using engineered encapsulins and virus-like particles.

Main Results:

• Engineered encapsulins formed non-icosahedral structures displaying the SARS-CoV-2 RBD peptide.
• The immunogen elicited conformationally relevant humoral responses against the SARS-CoV-2 RBD.
• A prime/boost strategy using orthogonal nanoparticles enhanced immune recognition and generated selective antibody responses against an RBD point mutant.

Conclusions:

• Engineered encapsulins serve as viable platforms for presenting viral antigens.
• Orthogonal nanoparticle strategies can precisely control epitope-focused antibody generation.
• This approach offers a method for developing targeted vaccines against viral pathogens like SARS-CoV-2.