LPS/TLR4-Activating Exosomes from M1-Polarized Avian Macrophages Enhances IBV Vaccine-Induced Protective Immunity in Chickens

Infectious bronchitis virus (IBV) presents a substantial economic burden to poultry production due to extensive serotypic diversity and limited cross-protection afforded by conventional vaccines. This study evaluated exosomes derived from M1-polarized chicken macrophages (HD11M1-exo) as a novel adjuvant for IBV vaccination. HD11M1-exo, isolated from LPS-activated HD11 macrophages via ultracentrifugation, demonstrated significant immunomodulatory properties across multiple experimental systems. In vitro analyses revealed HD11M1-exo enhanced macrophage phagocytosis and cellular immune activation via the LPS/TLR4 signaling pathway. In embryonated eggs, HD11M1-exo pre-treatment induced TNF- upregulation, enhanced viral resistance, and reduced pathological damage. In chickens, HD11M1-exo administration elevated CD80/CD86 and TGF-{beta}4 expression in respiratory tissues and increased secretory IgA in lacrimal fluid. When combined with H120 vaccine, HD11M1-exo significantly augmented both humoral immunity (elevated serum IgY and mucosal IgA) and cellular responses (increased CD80/CD86 expression), surpassing commercial adjuvants in efficacy. Following viral challenge, HD11M1-exo+H120 immunized chickens exhibited significantly reduced viral loads and attenuated histopathology compared to controls. These data collectively suggest that exosome-based formulations may serve as effective adjuvants for enhancing poultry vaccine immunogenicity and protective efficacy.