Carvacrol nanoemulsion significantly boosts H9N2 avian influenza vaccine efficacy in broiler chickens

The persistent threat of avian influenza outbreaks and potential pandemics necessitates effective vaccines. However, current avian influenza vaccines face challenges due to rapid antigenic drift and variable immune responses, leading to reduced efficacy. There is a critical need for novel adjuvants that can enhance vaccine immunogenicity and provide broader, more robust protection. Carvacrol, a natural compound with known immunomodulatory properties, is being explored as a potential adjuvant, particularly in a nano-emulsion formulation for improved delivery and bioavailability.

This in vivo study evaluated the adjuvant effect of carvacrol and carvacrol nano-emulsion on H9N2 avian influenza vaccine efficacy in broiler chickens. Researchers assessed immunological responses, including phagocytic activity, hemagglutination titters, and immune organ indices. Biochemical analysis measured levels of immunomodulatory cytokines IL-10, IL-12, and IFN-γ. Molecular analysis, likely via qPCR, quantified gene expression for IFN-γ, IL-12, IL-10, TLR4, TLR3, and TLR1, alongside CD3 expression in immune organs (bursa of Fabricius, thymus, spleen). Immunohistopathology of lung and trachea was conducted post-viral challenge to evaluate structural integrity.

Carvacrol, particularly in its nano-emulsion form, significantly enhanced immune responses in broiler chickens. Researchers observed increased phagocytic activity, higher hemagglutination titters, and improved immune organ indices. Biochemical analysis revealed significantly elevated levels of the immunomodulatory cytokines IL-10, IL-12, and IFN-γ. Molecular analysis showed upregulation of genes associated with IFN-γ, IL-12, IL-10, TLR4, TLR3, and TLR1. A notable increase in CD3 expression was also observed in the bursa of Fabricius, thymus, and spleen, suggesting enhanced T-cell-mediated immunity and improved pathogen recognition. The enhanced immunogenicity of the influenza vaccine via carvacrol nano-emulsion resulted in stronger protection against the H9N2 virus. > This led to ameliorated clinical picture and preserved the structural integrity of lung and trachea post-viral challenge, demonstrating robust protection.