Nano-adjuvants enhance the immunogenicity and safety of infectious bursal disease virus vaccines: a comprehensive review.

Infectious bursal disease virus (IBDV) remains a major global threat to poultry, causing severe immunosuppression and substantial economic losses. Existing vaccines live-attenuated, inactivated, and subunit provide incomplete protection and face challenges of safety, antigenic mismatch, and repeated dosing requirements. Nano-adjuvant technologies offer a transformative solution, enhancing vaccine immunogenicity, stability, and targeted delivery. Platforms include lipid nanoparticles, polymeric systems, virosomes, mesoporous silica, polysaccharides, and nanoemulsions elicit robust humoral and cellular immune responses, promote Th1/Th2 balance, and enable dose-sparing strategies. Toll-like receptor agonist-loaded nano-adjuvants further amplify dendritic cell activation, antigen presentation, and durable memory responses. Virus-like particles and virosomes structurally mimic IBDV antigens, enhancing immunogenicity without the risks of viral replication. Rational integration of precise antigen selection, multifunctional nano-adjuvants, and advanced delivery approaches promises next-generation vaccines capable of broad, long-lasting protection against very virulent and emerging IBDV variants. These innovations have the potential to revolutionize poultry vaccination, offering safer, more effective, and globally deployable strategies to safeguard poultry health and productivity.