ABSTRACT
In order to screen better flavone prescriptions of anti-Newcastle disease virus (NDV), four flavone ingredients of epimedium flavones (EF), baikal skullcap root flavones (BSRF), wild dendranthema flower flavones (WDFF), and sanchi flavones (SF) screened in previous experiments and their prescriptions were added into chicken embryo fibroblast monolayer with three drug-adding modes respectively. The cellular A(570) values, the highest virus inhibitory rates and the score based on virus inhibitory rate were calculated to compare their antiviral activity. In immune protective test, the effects of three preparations (EF-BSRF, EF-SF-WDFF-BSRF and EF-WDFF-BSRF screened by the results in vitro experiment) on NDV infection were compared in chickens vaccinated with ND vaccine then challenged with NDV. Blood was regularly sampled for serum antibody titer determination. The pathogenic and dead statuses of chickens were clinically examined. The results indicated that the A(570) values of the nine prescriptions, especially the foresaid three prescriptions at almost all concentrations in three drug-adding modes were significantly higher than that of the virus control group. The foresaid three prescriptions presented at the top five of the highest virus inhibitory rate, and located at the highest three of the score rank. The antibody titers and protective rates of the three prescriptions groups were higher than that of VC group, especially EF-SF-WDFF-BSRF group showed significant difference. These results indicated that flavone prescriptions composed with suitable compatibility could possess synergistical action of antiviral effect, ES-SF-WDFF-BSRF prescription could inhibit the cellular infectivity of NDV, improve the protective effect of ND vaccine and would be expected to exploit into a new-type antiviral drug.
