Crosslinked flagella as a stabilized vaccine adjuvant scaffold

Area of Science:

• Biotechnology
• Immunology
• Microbiology

Background:

• Engineered vaccine proteins combine antigen and adjuvant functions for enhanced immunity.
• Bacterial flagellin offers adjuvant activity via TLR5 and inflammasome activation.
• Polymerized flagellin filaments elicit a more robust immune response than monomeric forms.

Purpose of the Study:

• To produce and test covalently stabilized polymerized flagellar filaments.
• To enhance immune efficacy through stabilization of filament structure and long-term storage.
• To explore flagellin's potential as a vaccine adjuvant.

Main Methods:

• Computational modeling identified amino acids for disulfide cross-linking.
• Paired cysteine substitutions were introduced into flagellin.
• Transfection into Salmonella enterica subspecies Typhimurium created stabilized flagella.

Main Results:

• Disulfide cross-links stabilized flagellar filaments in various conditions (acid, heat, detergent).
• Stabilized filaments retained immunostimulatory function, inducing epithelial NF-κB.
• Bacterial virulence and adherence/invasion capabilities remained unimpaired.

Conclusions:

• Amino acid substitutions created disulfide bonds, stabilizing flagellar filaments.
• Stabilized flagella maintain immunostimulatory function and offer improved stability.
• Disulfide-stabilized flagella present new possibilities for vaccine adjuvant applications, including long-term storage and varied delivery conditions.