Anti-virus activity induced by polyinosinic:polycytidylic acid copolymer in in vitro chick embryo fibroblast cells.

The effect of a polyinosinic:polycytidylic acid copolymer (Poly I:C) on chick embryo fibroblast (CEF) cell viability, anti-Newcastle disease virus (NDV) activity and on IFN-alpha and IFN-beta levels were determined in vitro. Poly I:C inhibited NDV growth in CEF cells in the range of 30-500 microg/mL and over 0.75-12 h of treatment.The anti-NDV activity was maximal for 60 microg/mL of Poly I:C treatment at 12 h, after which it declined. The result of VSV protection assay which was used to determine IFN-activity showed that Poly I:C inhibited VSV growing on CEF cells, indicating that Poly I:C had immune-stimulating activities.The amount of IFN-beta in cell supernatant and the transcription levels of IFN-alpha mRNA and IFN-beta mRNA increased after Poly I:C treatment, indicating that the anti-viral activity related to the production of type I IFN. However Poly I:C also showed a toxic effect by inhibiting CEF cell proliferation in a dose-dependent and time-dependent manner.The results of this study indicate that the dosage level of Poly I:C must be carefully considered when used in a clinical setting.