Antiviral effects of compound traditional Chinese medicine on Newcastle disease virus.

[Objective] To investigate the mechanism of compound traditional Chinese medicine(TCM) on Newcastle disease virus(NDV) and to provide a scientific basis for the reasonable usage of antiviral drugs in clinic.[Method] The compound TCM was composed of Hedyotis diffusa,Lonicera japonica Thunb,Radix astragali and Glycyrrhiza uralensis.Different dilutions of fluid extract were prepared.Its antiviral effects on NDV were observed through three inoculation ways:first,inoculation with the medicine and NDV mixture which had been incubated at 37 °C;second,incubating chicken embryo fibroblasts(CEF) with the medicine followed by inoculation with NDV;third,inoculation with NDV followed by incubating CEF with the medicine.The A498 was determined by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)] method.Therapeutic indexes were used to evaluate the antiviral effects.[Result] The minimum effective concentration of the compound TCM which acted through the three ways was 1.0 × 2-10,1.0 × 2-8 and 1.0 × 2-7 g/ml,respectively.The antiviral effects of the compound TCM were the best through inoculation with the incubated medicine and NDV mixture,followed by the second method and the third method.[Conclusion] The compound TCM can not only kill NDV directly in vitro but also inhibit viral propagation.