Submitted to: Avian Immunology Research Group Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/30/2010
Publication Date: N/A
Technical Abstract: Ducks have been implicated in the dissemination and evolution of H5N1 highly pathogenic avian influenza (HPAI) viruses. Differences in pathogenicity and response to vaccination have been observed between different duck species. The innate immune system is responsible for controlling viruses during the initial stages of infection, which is crucial in determining disease resistance or susceptibility. The objective of this study was to examine the differences in innate immune responses among two domestic ducks species, Pekin (Anas. platyrhynchos, var. domestica) and Muscovy (Cairina moschata), and a wild type species, Mallard (A. platyrhynchos) infected with a H5N1 HPAI virus. All challenged ducks died, but Muscovy ducks died 2 days earlier than Pekin and Mallard ducks. However, high virus titers were present in all duck tissues, with a significant higher titer only observed in the heart of the Muscovy ducks. On the other hand, Pekin and Mallard ducks had higher body temperatures after infection than Muscovy ducks, indicating differences in the innate immune response between the ducks. Despite being genetically more closely related, no obvious gene expression pattern emerged that was shared by both domestic Pekin and wild Mallard duck species, but lacking in the more susceptible Muscovy ducks. However, higher levels of IL-6, IL-18, and chemokine SicA19 gene expression were observed in the Muscovy ducks. RIG1, MHC-I, and IFNg gene expression were also upregulated in all three duck species. In contrast, MHC-II was down regulated. Differences were also found in TLR7 and IFNa gene expression. In conclusion, the differences observed in the expression of innate immune related genes between these duck species could explain in part the differences observed in pathogenicity.