A synthetic cyclic peptide for promoting antigen presentation and immune activation

Area of Science:

• Vaccinology
• Immunology
• Materials Science

Background:

• Cyclic peptides offer stable scaffolds for multivalent drug presentation.
• Lipoamino acid-containing cyclic decapeptides can deliver T helper and B cell epitopes for robust humoral immunity.

Purpose of the Study:

• To assess the function-immunogenicity of a multi-component vaccine candidate (VC-13).
• To elucidate the mechanism of action for a novel vaccine delivery platform.
• To evaluate the platform's versatility in delivering diverse antigens.

Main Methods:

• Developed a cyclic decapeptide incorporating lipoamino acids for antigen delivery.
• Formulated vaccine candidates (VC-13) that self-assembled into nanoparticles (<500 nm).
• Assessed immune responses, including IgG titers and opsonic potential, compared to a commercial adjuvant.

Main Results:

• Vaccine candidates effectively delivered peptide epitopes, protein antigens (e.g., SARS-CoV-2 RBD), and small molecule haptens.
• Self-assembled nanoparticles induced high antigen-specific IgG titers and opsonic potential, outperforming complete Freund's adjuvant.
• The cyclic decapeptide enhanced antigen accumulation in lymph nodes, and lipoamino acids activated dendritic cells via TLR2 and TLR4.

Conclusions:

• The cyclic decapeptide and lipoamino acid components are crucial for effective antigen presentation and immune activation.
• This study presents a promising, fully synthetic, self-assembled platform for subunit and anti-drug vaccines.
• The platform demonstrates broad applicability for delivering various types of antigens.