Chicken IFN-γ monoclonal antibodies and their application in enzyme-linked immunosorbent assay

Twelve mabs against native or recombinant chicken IFN-γ were produced and characterized by virus neutralization, ELISA, and Western blot assays. No data were obtained to suggest that the form of the immunogen (native versus recombinant) influenced the antigenic specificity of the mabs produced. While only two antibodies inhibited the in vitro virus neutralizing activity of IFN-γ, other evidence indicated that the specificity of these mabs was indeed directed against IFN-γ. By Western blot analysis, all antibodies identified a 17-kDa IFN-γ polypeptide. Using a direct binding ELISA incorporating these mabs, a high correlation with IFN-γ detected by in vitro virus neutralization was observed. The IFN-γ ELISA was also capable of measuring cytokine levels in the sera of chickens orally infected with Eimeria maxima. At 8 and 10 days post-primary infection, significantly higher (p<0.001) levels of serum IFN-γ were detected in E. maxima infected chickens compared to uninfected controls. These results indicate that a mab-based direct binding ELISA is suitable to measure chicken IFN-γ in a variety of formats.