Vaccination with CpG-adjuvanted avian influenza virosomes promotes antiviral immune responses and reduces virus shedding in chickens

The use of virosomes as a vaccine platform has proven successful against several viruses. Here we examined the protective efficacy of a virosome-based vaccine consisting of avian influenza virus (AIV) A/Duck/Czech/56/H4N6 in chickens against a homologous AIV challenge. Virosomes adjuvanted with CpG-ODN or recombinant chicken interferon (IFN)-gamma significantly reduced virus shedding after virus challenge. Furthermore, immunization with virosomes adjuvanted with CpG-ODN increased hemagglutination inhibition (HI) and virus-specific neutralizing serum antibodies, as well as virus-specific serum IgG and mucosal IgA responses. We also found a significant increase in the expression of type I and II interferon genes in the protected birds following virus challenge. In summary, this study demonstrated the ability of virosomes adjuvanted with CpG-ODN to reduce AIV shedding, and elicit virus-specific protective antibody responses in vaccinated birds.