Innate immune response gene expression profiles in specific pathogen-free chickens infected with avian influenza virus subtype H9N2

Abstract

In poultry species, H9N2 low pathogenic avian influenza (LPAI) virus infections frequently lead to low to moderate mortality rates and morbidity characterized by depression, respiratory disease symptoms, and decreases in egg production. Since current knowledge on the avian immune response to H9N2 infection is limited, we used microarray analysis to examine global changes in immune-related gene expression induced by H9N2 LPAI infection in specific pathogen-free chickens. The expression profiles of approximately 800 genes, including those that influence cell differentiation, transcription, transport, immune responses, and signal transduction, were altered by H9N2 infection. A complete chicken genome microarray analysis identified a strong innate antiviral host response after infection in spleens. In particular, a significant number of immune response genes, including interferon genes and related immune response genes, were upregulated following H9N2 infection. The increased transcription of 2'-5'-oligoadenylate synthetase and myxovirus resistance genes was confirmed by real-time RT-PCR. These results suggest that the host response generated against H9N2 infection may contribute to protective effects by manipulating innate immune responses.