Recombinant Chicken Interferon-α Inhibits H9N2 Avian Influenza Virus Replication In Vivo by Oral Administration

Chicken interferon-alpha (ChIFN-alpha) has been demonstrated to be an important cytokine in antiviral immunity. However, the preventive or therapeutic effect of ChIFN-alpha as an oral antiviral agent on avian influenza virus (AIV) infection has not been fully clarified in chickens systemically. In the present study, we investigated the anti-H9N2 AIV effect of ChIFN-alpha on a cohort of 7- and 33-day-old specific pathogen-free (SPF) chickens by oral administration. Results showed that both the ChIFN-alpha preventive and therapeutic groups exhibited significantly reduced viral load in trachea when compared with the virus-challenged control group. The therapeutic effect was better than the preventive effect on 7-day-old SPF chickens, which is opposite to 33-day-old SPF chickens. We speculated that T-dependent lymphocyte system of 33-day-old SPF chickens might be easier to be stimulated by ChIFN-alpha than that of 7-day-old SPF chickens. In addition, there was no side effect on the body weight of chickens treated with ChIFN-alpha. We also found that IFN-stimulated genes (ISGs) (2',5'-oligoadenylate synthetase and Mx1) were upregulated in groups treated by ChIFN-alpha and/or virus, indicating that these 2 ISGs not only participated in anti-AIV response in vivo but also could be induced by oral administration of ChIFN-alpha. The present study suggested that ChIFN-alpha could be used as a potential preventive and therapeutic antiviral agent against H9N2 AIV infection by oral administration.