title: Cytokine expression in three chicken host systems infected with H9N2 influenza viruses with different pathogenicities.
abstract: SD/818 and SD/196 are H9N2 influenza virus strains isolated from chickens from the same farm at different times that exhibited similar genetic evolution. However, strain SD/818 exhibited higher pathogenicity in chickens than strain SD/196 and other H9N2 influenza virus epidemic strains from China. The expression of cytokines is an important host defence mechanism following viral infection and their intensity is a major determinant of viral pathogenicity. To elucidate the mechanism underlying the increased pathogenicity of strain SD/818 from the host's perspective, viral replication and cytokine expression were dynamically studied using real-time quantitative reverse transcription PCR in chickens infected with strain SD/818 compared with chickens infected with strain SD/196 in this study. The results showed that the replication of strain SD/818 and the expressions of IL-1β, IL-6, TNF-α, IFN-α and IFN-β induced by strain SD/818 were higher than those induced by strain SD/196 in the chicken host system. Expression of these cytokines in chickens coincided with or followed virus replication. These results suggested that high-level viral replication and pro-inflammatory cytokine expression (but not decreased type I IFN expression) were associated with the higher pathogenicity of strain SD/818 in chickens.
authors.affiliation: a College of Animal Science and Technology, Qingdao Agricultural University , Qingdao , People's Republic of China.
authors.forename: Jianlin
authors.initials: J
authors.lastname: Wang
authors.affiliation: a College of Animal Science and Technology, Qingdao Agricultural University , Qingdao , People's Republic of China.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Cao
authors.affiliation: a College of Animal Science and Technology, Qingdao Agricultural University , Qingdao , People's Republic of China.
authors.forename: Xuejin
authors.initials: X
authors.lastname: Guo
authors.affiliation: b China Animal Health and Epidemiology Center , Qingdao , People's Republic of China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: a College of Animal Science and Technology, Qingdao Agricultural University , Qingdao , People's Republic of China.
authors.forename: Dongdong
authors.initials: D
authors.lastname: Wang
authors.affiliation: a College of Animal Science and Technology, Qingdao Agricultural University , Qingdao , People's Republic of China.
authors.forename: Shouzheng
authors.initials: S
authors.lastname: Xu
authors.affiliation: a College of Animal Science and Technology, Qingdao Agricultural University , Qingdao , People's Republic of China.
authors.forename: Yanbo
authors.initials: Y
authors.lastname: Yin
mesh_terms: D000818:Animals; D002642:Chick Embryo; D002645:Chickens / Q000276:immunology* / Q000821:virology; D002681:China; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D005260:Female; D054884:Host-Pathogen Interactions; D053127:Influenza A Virus, H9N2 Subtype / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity / Q000502:physiology; D005585:Influenza in Birds / Q000276:immunology* / Q000821:virology; D011201:Poultry Diseases / Q000276:immunology* / Q000821:virology; D013045:Species Specificity; D013047:Specific Pathogen-Free Organisms; D014779:Virus Replication
chemical_list: D016207:Cytokines
keywords: H9N2 influenza virus; antiviral cytokines; chicken; pathogenicity; pro-inflammatory cytokines