Interleukin-6 expression after infectious bronchitis virus infection in chickens.
Viral infections in chickens pose a major health threat to the poultry industry. Infectious bronchitis virus (IBV) usually causes respiratory disease; however, the disease severity is influenced by the genotype of the chicken and the IBV strain involved. Nephropathogenic strains of IBV, such as the Australian T strain, can cause high mortalities due to kidney failure characterized by mononuclear cell infiltration and inflammation. In a previous study, a line of specific pathogen-free chickens, the S-line, was shown to be susceptible to high mortalities from IBV infection. The cause of these high mortalities is unknown but it is suspected that differential cytokine expression may play a role. With this in mind, we decided to study the role of the proinflammatory cytokine interleukin (IL)-6 during infection to determine its contribution to nephritis and influence on disease susceptibility. To investigate this, we infected the susceptible S-line and the more disease-resilient HWL line with the T strain of IBV and measured their cytokine response levels. In both lines of birds, IL-6 mRNA levels were elevated in the kidneys at 4 d postinfection. However, in S-line chickens, these levels were 20 times higher than those in the HWL chickens. In addition, S-line birds also showed three times higher serum IL-6 levels than HWL birds after IBV infection. These findings suggest that IL-6 may play a role in IBV-induced nephritis and may open an avenue to develop alternative strategies, such as the use of antiinflammatory cytokines, to overcome the nephropathogenic effects of IBV.
Asif
Manija
M
CSIRO Livestock Industries, Australian Animal Health Laboratory, Geelong, Australia.
Lowenthal
John W
JW
Ford
Mark E
ME
Schat
Karel A
KA
Kimpton
Wayne G
WG
Bean
Andrew G D
AG
D000818:Animals; D002645:Chickens; D018352:Coronavirus Infections / Q000150:complications / Q000276:immunology / Q000662:veterinary*; D004198:Disease Susceptibility / Q000276:immunology; D015870:Gene Expression; D001351:Infectious bronchitis virus / Q000276:immunology*; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000097:blood / Q000235:genetics; D007668:Kidney / Q000276:immunology / Q000473:pathology; D009393:Nephritis / Q000276:immunology; D011201:Poultry Diseases / Q000276:immunology*; D012333:RNA, Messenger / Q000096:biosynthesis; D013047:Specific Pathogen-Free Organisms; D014158:Transcription, Genetic
D015850:Interleukin-6; D012333:RNA, Messenger