Antiviral Effects of Olea europaea Leaves Extract and Interferon-beta on Gene Expression of Newcastle Disease Virus

In this study, we investigated the antiviral activity of Olea europaea (OLE) extracts against Newcastle disease virus (NDV), a highly infectious and economically important poultry virus. For this purpose, viral gene expressions of two structural proteins, matrix (M) and fusion (F) of NDV, were monitoring in chicken fibroblast cells and the impact on virus replication was analyzed using qRT-PCR. Additionally, the virus-restriction activities of IFN-β were analyzed by assessing the expression of viral and host genes. In vitro analysis of the NDV replication revealed that treatment of chicken cells with OLE significantly restricted the NDV replication as was measured by haemagglutination (HA) and titration (TCID50) assays in a pre-optimized OLE-mediated cytotoxicity levels (1000ug/ml). Correspondingly, pretreatment of chicken cells with exogenous IFN-β markedly down-regulated viral gene expression, and this regulation was higher than OLE-mediated virus replication. Furthermore, the impact of OLE on NDV was independent of the IFN-β and was confirmed using ELISA. Taken together, findings of this study propose the utilization of OLE as immunoprophylaxis and exploitation of this function to control the ND in poultry and pet birds.