Abstract
Current commercial H9 avian influenza vaccines cannot provide satisfactory protective immunity against antigenic variant influenza viruses in ducks. Poly I:C, when used as an adjuvant, improves humoral and cellular immunity in many animals but has not been tested in ducks. In this study, we investigated the protective efficacy of Poly I:C as an adjuvant for an inactivated H9N2 Avian influenza vaccine in ducks. We found that an H9N2 vaccine administered with poly I:C (H9-PIC vaccine) induced a significantly more rapid response with higher anti-influenza antibody titers than those of the vaccine alone (H9 vaccine). Moreover, virus shedding was reduced in ducks immunized with the H9-PIC vaccine after challenge with an H9 subtype antigenic variant viruses. IFN-α, IFN-γ, IL-6 and MHC-II mRNA levels were all elevated in ducks receiving the H9-PIC vaccine. In addition, lower expression level of MHC-I may be a reason for inefficient protective ability against heterologous influenza viruses in H9-PIC vaccination of ducks. In conclusion, poly I:C adjuvant enhanced both humoral and cellular immune responses in ducks induced by immunization of inactivated H9N2 vaccine.
Highlights
Avian influenza viruses (AIV) have a worldwide distribution in a variety of animals including humans, pigs, wild birds and domestic poultry [1, 2]
The results showed that higher hemagglutination inhibition (HI) titers in the H9-PIC group as compared to H9 group at the 14, 21and 28 dpv, which may be involved in polycytidylic acid (poly I):C as adjuvant improved serum HI antibody levels and inducing cross-protective immunity against antigenic variant SIC9/13 and SIC10/13 viruses
This study demonstrated that H9-PIC vaccine more rapidly induced elevated antibody levels and reduced viral shedding against the heterogeneous antigenic variant H9N2 influenza in ducks
Summary
Avian influenza viruses (AIV) have a worldwide distribution in a variety of animals including humans, pigs, wild birds and domestic poultry [1, 2]. This group of viruses is responsible for major economic losses to the poultry industry and responsible for influenza infection in humans [3]. Ducks are the principal natural reservoir for the H9N2 strain of AIV. This antigenic subtype contributed genetic material to the zoonotic H7N9 strain that was responsible for a recent outbreak. Genetic exchange between subtypes plays an important role in AIV dissemination and evolution [1, 2].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
