Pre-immune state induced by chicken interferon gamma inhibits the replication of H1N1 human and H9N2 avian influenza viruses in chicken embryo fibroblasts.
BACKGROUND
Interferon gamma (IFN-γ), an immunoregulatory cytokine, is known to control many microbial infections. In a previous study, chicken interferon gamma (chIFN-γ) was found to be up-regulated following avian influenza virus (AIV) infection in specific pathogen-free chickens. We aimed to investigate whether the pre-immune state induced by chIFN-γ could generate an antiviral response against influenza virus.


METHODS
We generated a chIFN-γ-expressing plasmid and transfected it into chicken embryo fibroblasts (CEFs) and then infected the cells with human origin H1N1 or avian origin H9N2 influenza viruses. Viral titers of culture medium were evaluated in MDCK cell and the viral RNA and IFN-stimulated genes (ISGs) were then quantified by real-time reverse transcriptase polymerase. To further evaluate the role of the antiviral effect of chIFN-γ by using a backward approach, synthetic small interfering RNAs (siRNA) targeting chIFN-γ were used to suppress chIFN-γ.


RESULTS
The chIFN-γ-stimulated CEFs inhibited the replication of viral RNA (vRNA) and showed a mild decrease in the infectious virus load released in the culture medium. Compared to the mock-transfected control, the messenger RNA (mRNA) levels of type I IFNs and IFN-stimulated genes were up-regulated in the cells expressing chIFN-γ. After treatment with the siRNA, we detected a higher expression of viral genes than that observed in the mock-transfected control.


CONCLUSIONS
Our results suggest that apart from the important role played by chIFN-γ in the antiviral state generated against influenza virus infection, the pre-immune state induced by chIFN-γ can be helpful in mitigating the propagation of influenza virus.
Department of Avian Diseases Laboratory, College of Veterinary Medicine, Konkuk University, Seoul, Korea.
Seong-Su
SS
Yuk
Department of Avian Diseases Laboratory, College of Veterinary Medicine, Konkuk University, Seoul, Korea.
Dong-Hun
DH
Lee
Department of Avian Diseases Laboratory, College of Veterinary Medicine, Konkuk University, Seoul, Korea.
Jae-Keun
JK
Park
Department of Avian Diseases Laboratory, College of Veterinary Medicine, Konkuk University, Seoul, Korea.
Erdene-Ochir
EO
Tseren-Ochir
Department of Avian Diseases Laboratory, College of Veterinary Medicine, Konkuk University, Seoul, Korea.
Jung-Hoon
JH
Kwon
Department of Avian Diseases Laboratory, College of Veterinary Medicine, Konkuk University, Seoul, Korea.
Jin-Yong
JY
Noh
Department of Avian Diseases Laboratory, College of Veterinary Medicine, Konkuk University, Seoul, Korea.
Joong-Bok
JB
Lee
Department of Avian Diseases Laboratory, College of Veterinary Medicine, Konkuk University, Seoul, Korea.
Seung-Yong
SY
Park
Department of Avian Diseases Laboratory, College of Veterinary Medicine, Konkuk University, Seoul, Korea.
In-Soo
IS
Choi
Department of Avian Diseases Laboratory, College of Veterinary Medicine, Konkuk University, Seoul, Korea. songcs@konkuk.ac.kr.
Chang-Seon
CS
Song
D000818:Animals; D002645:Chickens; D005347:Fibroblasts / Q000187:drug effects / Q000276:immunology* / Q000821:virology*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology* / Q000502:physiology; D053127:Influenza A Virus, H9N2 Subtype / Q000276:immunology* / Q000502:physiology; D007371:Interferon-gamma / Q000378:metabolism*; D012367:RNA, Viral / Q000032:analysis; D060888:Real-Time Polymerase Chain Reaction; D019562:Viral Load; D010948:Viral Plaque Assay; D014779:Virus Replication
D012367:RNA, Viral; D007371:Interferon-gamma
Chicken embryo fibroblast; Chicken interferon gamma; Influenza virus; Interferon stimulated genes; Pre-immune state