Assay of Chick Interferon Activity in Chick Kidney Cell Culture

The availability of chick kidney cells (CK) for the assay of chick interferon was tested. When a single preparation of interferon was titrated in cultures of both CK and chick embryo fibroblasts (CEF) by the dye uptake method with vesicular stomatitis virus as challenge, the titer in 50% dye uptake (DU_<50>) units obtained in CK was approximately 4 times (0.6 log units) higher than that obtained in CEF. The reproducibility of the assay, as well as its sensitivity, was satisfactory, with the variation coefficient of approximately 10%. From these experimental data, it is concluded that the cultures of CK can well be used for the assay of chick interferon in place of those of CEF