Immune responses and pathogenesis in immunocompromised chickens in response to infection with the H9N2 low pathogenic avian influenza virus.
The H9N2 low pathogenic avian influenza (LPAI) viruses have often caused moderate mortality with severe clinical signs in domestic poultry in many Eurasian countries and have occasionally caused clinical respiratory diseases in humans, but the basis for their pathogenesis remains unclear especially in chickens. To better understand the effect of immunosuppression on the risk of H9N2 viral infection, the pathogenesis and host immune responses of the H9N2 LPAI virus in a T-cell-suppressed chicken model were investigated. Cyclosporin A (CsA) treatment led to suppression of cell-mediated immunity such as CD8+ T-cells and reduced expression of IFN-gamma mRNA. T-cell suppression correlated with high viral load in the oropharynx and cloaca of H9N2 LPAI virus-infected specific pathogen free (SPF) chickens. Elevated level of viral RNA in the peripheral blood lymphocytes was found only in immunocompromised chickens. Viral protein and associated cellular apoptosis were observed only in the kidney of the immunocompromised chickens, particularly in those that had died. Our findings suggest that T-cell-mediated responses are important in influenza viral clearance and may help to explain in part the reasons for the increased mortality in chickens infected with H9N2 LPAI viruses in domestic poultry farms.
Kwon
Ji-Sun
JS
Avian Disease Laboratory, College of Veterinary Medicine, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea.
Lee
Hyun-Jeong
HJ
Lee
Dong-Hun
DH
Lee
Youn-Jeong
YJ
Mo
In-Pil
IP
Nahm
Sang-Seop
SS
Kim
Min-Jeong
MJ
Lee
Joong-Bok
JB
Park
Seung-Yong
SY
Choi
In-Soo
IS
Song
Chang-Seon
CS
D000818:Animals; D002645:Chickens; D016572:Cyclosporine / Q000008:administration & dosage; D016867:Immunocompromised Host; D007165:Immunosuppression Therapy; D007166:Immunosuppressive Agents / Q000494:pharmacology; D053127:Influenza A Virus, H9N2 Subtype / Q000276:immunology / Q000472:pathogenicity*; D005585:Influenza in Birds / Q000276:immunology* / Q000401:mortality / Q000503:physiopathology* / Q000821:virology; D013047:Specific Pathogen-Free Organisms; D013601:T-Lymphocytes / Q000276:immunology*
D007166:Immunosuppressive Agents; D016572:Cyclosporine