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Expression of interferon gamma by a highly virulent Newcastle disease virus decreases its pathogenicity in chickens

Susta, Leonardo, Cornax, Ingrid, Diel, Diego G., Garcia, Stivalis Cardenas, Miller, Patti J., Liu, Xiufan, Hu, Shunlin, Brown, Corrie C., Afonso, Claudio L.
Microbial pathogenesis 2013 v.61-62 pp. 73-83
Newcastle disease virus, antiviral properties, chickens, death, disease severity, genome, green fluorescent protein, immunomodulation, interferon-gamma, mortality, pathogenesis, pathogenicity, protective effect, viral antigens, virus replication, viruses
Infection of chickens with highly virulent NDV results in rapid death, which is preceded by increased expression of interferon gamma (IFN-g) in target tissues. IFN-g is a cytokine that has pleiotropic biological effects including intrinsic antiviral activity and immunomodulatory effects. Here we assessed the effects of IFN-g on NDV pathogenesis in chickens. For this, the coding sequence of chicken interferon gamma was inserted in the genome of the highly virulent NDV strain ZJ1 (rZJ1-IFNg), and the effects of IFN-g expression were determined in vivo by comparing the pathogenesis of rZJ1-IFNg with a control virus expressing the green fluorescent protein (rZJ1-GFP). Expression of IFN-g decreased the intra cerebral pathogenicity index (ICPI) of rZJ1-IFNg, when compared to the control rZJ1-GFP. Additionally rZJ1-IFNg presented a marked decrease in pathogenicity in 4-week-old chickens, as evidenced by lower mortality rates, decreased disease severity, viral shedding, and antigen distribution. These results suggest that early expression of IFN-g during viral replication has a protective effect against virulent NDV infection in chickens, and further suggests that the level and time of expression of IFN-g are critical for the disease outcome.