Study On The Antiviral Activity Of Ginkgo Biloba Exocarp Polysaccharide And Baicalin On Replication Of Avian Leukosis Virus

BackgroundAvian leukosis virus is a carcinogenic retrovirus of poultry,which can cause cancer.There is no effective drug treatment and prevention.Although there are many domestic and foreign antiviral drugs have been developed,almost of them have toxic side effects.The virus is easy to produce resistance,and the type of anti-virus is also limited.Compared with western medicine,traditional Chinese medicine has the advantages of low drug resistance,small side effects,and can inhibit the function of virus replication and immune function.According to the relevant literature,Ginkgo biloba exocarp polysaccharide and baicalin have a broad spectrum of antiviral effects,baicalin can inhibit the same retrovirus virus replication also.Based on these we prefer these two drugs as anti-avian leukosis virus research.AimIn this study,we studied the antiviral activity of traditional Chinese medicine on the basis of the previous study.Two kinds of common antiviral Chinese medicine,Ginkgo biloba polysaccharide and baicalin were studied on the replicaiton and proliferation of avian leukosis virus subgroup J in DF-1 cell,and further explore the specific mechanism of Chinese medicine to regulate cell antiviral activity.Methods1.The cytotoxicity of Ginkgo biloba exocarp polysaccharide and baicalin on DF-1 cells was determined by cytotoxicity assay.The antiviral effects of these two drugs were identified by quantitative Real-time PCR.2.The in vitro experiments,quantitative real-time PCR,Western blot and TCID50 were used to study the antiviral activity and its mechanism of Ginkgo biloba polysaccharide and baicalin in DF-1 cells infected with ALV-J.3.The in vivo experiments used 130 days of chicken infected with ALV-J as an experimental animal model.The separated peripheral blood lymphocytes were treated with different concentration of baicalin in vitro for 16 hours,and then analyzed cell apoptosis rate by flow cytometry in order to identify the baicalin pro-apoptotic effect.Results1.Determination of Ginkgo biloba exocarp polysaccharide in DF-1 cells when the drug concentration at 200μg/mL is still no cytotoxicity,while no cytotoxic dose of baicalin is 20μg/mL.Preliminary identification of Ginkgo biloba extract polysaccharide and baicalin could significantly down-regulate the gp37 gene expression of ALV-J in DF-1 cells.2.Respectively,in the gene and protein levels and the proliferation of the virus proved that Ginkgo biloba exocarp polysaccharide could effectively inhibit the replication of ALV-J.Ginkgo biloba exocarp polysaccharide effectively inhibited the virus replication mainly in the pre-treatment stage.Moreover,the expression levels of ISG12-2,TNF-α and IL-1β in viurs infected cells were significantly down-regulated by Ginkgo biloba extract.Whether this phenomenon is directly related to the inhibitory effect of Ginkgo biloba exocarp polysaccharide on viral replication remains to be further studied.3.Respectively,in the gene and protein levels and virus proliferation proved that baicalin can effectively inhibit the replication of ALV-J with a dose and time-dependent manner.The expression levels of ISG12-2,TNF-a and IL-1β in viurs infected were significantly down-regulated by baicalin also,which need to be addressed the relationship between the cytokine down-regulation and antivial effect.It was notted that baicalin could induce apoptosis of peripheral blood lymphocytes isolated from ALV-J infected chickens in vitro.And the proportion of apoptosis was dose-dependent.ConclusionGinkgo biloba exocarp polysaccharide and baicalin had significant antivial activity on ALV-J replication in DF-1 cells in vitro.And both of the drugs could down-regulate the expression level of ISG12-2,IL-1β and TNF-a cytokines.Whether this phenomenon is directly related to the inhibitory effect of Ginkgo biloba exocarp polysaccharide and baicalin remains to be further studied.Moreover,Baicalin could induce apoptosis of peripheral blood lymphocytes separated from chickens infected with ALV-J in vitro.The specific mechanism of apoptosis need to be further studied.