In this study, we examined the dose-dependent effects of the formula on Newcastle disease virus (NDV). In in-vitro test, the formula within safety concentration scope and NDV were added into cultured chick embryo fibroblast in 3 modes, and the cellular A570 values were determined by MTT (3-(4, 5-dimethyithiazol-2-yl)-2, 5-diphenyltetrazolium bromide) method. In in-vivo test, we examined the expression of interferon-induced transmembrane protein 3 (IFITM3) and Interferons (IFNs) in NDV-infected chickens. The results showed that the highest virus inhibitory rates of the formula at optimal concentration group were the highest (15.625 mg/mL) in post-adding and simultaneous-adding drug and virus modes, whereas medium concentration (7.813 mg/mL) showed the highest virus inhibitory rates in pre-adding drug mode. In vivo, the formula significantly upregulated the expression of IFITM3 in NDV-infected chickens at 3-D post-infection. However, the levels of IFNs were significantly downregulated. On days 5 and 7 post-infection, the levels of IFNs quickly upregulated. Moreover, the formula can significantly upregulate the antibody to resist the NDV compared with model control group on days 5 and 7 post-infection. In animals treated with the formula, the survival rate was nearly 37% higher at 7 d post-infection. We also found that the formula had a significantly stronger effect than a single herb on upregulating the expression of IFITM3. It confirmed that the formula could significantly inhibit the infectivity of NDV to chick embryo fibroblast. Also, the formula could significantly upregulated IFITM3 expression and inhibited virus replication in NDV-infected chickens. During the early stage of infection, IFNs were consumed to stimulate IFITM3 to inhibit virus replication, whereas during later stages of the infection, the formula upregulated the levels of IFNs and their antibodies to maintain a high level of immunity.
