Exosomes derived from avian influenza virus-infected chickens modulate host immune responses

Exosomes are emerging as key mediators of host-pathogen interactions, especially as carriers of viral components during infection. This study examined the immunomodulatory role of serum-derived exosomes from chickens infected with low pathogenic avian influenza virus (LPAIV) or highly pathogenic influenza virus (HPAIV). Brown Leghorn chickens were infected with either LPAIV or HPAIV, and serum exosomes were isolated. These exosomes (CTRL-EXO; noninfected, LPAIV-EXO, and HPAIV-EXO) were intramuscularly injected into naïve chickens, and several tissues and serum were collected. Cytokine gene expression in immune-related tissues (lung, spleen, and trachea) was quantified using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) to assess the immune response. Unlike the lung and trachea, the spleen exhibited the strongest immune response following exosome injection, with higher expressions of antiviral cytokines and interferons in the AIV-exosome group. In parallel, the same exosomes were applied to chicken macrophage HD11 cell lines to evaluate their cellular uptake and cytokine expression via RT-qPCR. Furthermore, immunocytochemistry was conducted to detect viral protein NP and NS1 delivered into HD11 cells by exosomes. LPAIV-EXO induced the most pronounced immune activation, as demonstrated by elevated cytokine expression and immunocytochemical detection of viral proteins. These findings indicate that AIV-derived exosomes can modulate host immune responses both in vivo and in vitro , highlighting their potential in immune regulation and vaccine development.