Functional Polysaccharide Of Grifola Frondosa Inhibit The Replication And Viability Of Enterovirus 71

Objective:According the reports, Hand, foot, and mouth disease (HFMD) is a common viral illness that usually afects infants and children, Enterovirus 71 (EV71),a member of the Enterovirus genus of the Picornaviridae virus family, it’s the most frequently detected pathogen in hand-foot-and-mouth disease (HFMD) patients, But until now there are no effective therapeutic medicines or vaccines for this disease. During recent epidemics of HFMD in China, Chinese herbs and preparations containing herbal extracts have demonstrated therapeutic eicacy against the disease, G. frondosa polysaccharide (GFP) has been used for its antitumor, antioxidant, immuneomodulatory, and antiviral activities. However, there is no report about the antiviral effect of Grifola frondosa against EV71.In this study we want to find that whether G. frondosa polysaccharide has antiviral activity then it can be used as a new anti-EV71 agent. At the same time we also want to do some researches to find the structure of the GFP, in order that we can find the relationship between the structure of GFP and the results of its antiviral activity.Methods:In this study,Fourier transform infrared (FT-IR) spectroscopy and nuclear magnetic resonance (1H NMR and 13CNMR) spectroscopy were used to investigate the structure of the purified G.frondosa polysaccharide (GFP), which inhibited EV71 infection significantly. Then the in vitro cytotoxicity was determined. The in vitro antiviral activity was determined via crystal violet staining assay. The western blot assay and the Real-time PCR were also used to validate the antiviral activity of G. frondosa polysaccharide (GFP).At the same time, time-of-drug addition assay were used to find wether the GFP was more effective when added during EV71 infection.Results:In this study, we found that the GFP it inhibited EV71 replication and showed that it could block viral polyprotein expression and genomic RNA synthesis. The results demonstrated that Grifola frondosa could effectively protect Vero cells from infecting and it has antiviral function during EV71-early-stage replication,and it validates the usefulness of GFP for the management of HFMD. Caspase-3 and VP1 were visualized via Western to find that it can suppressed EV71-induced caspase-3 cleavage.and we also found that EV71 induced the IκBα down regulation, however, GFP could inhibit that.Conclusions:The structure of GFP has already been found by the study,and it has been shown to have anti-EV71 activity and were more effective when added during the initial stage of the replication of EV71. The results could be used as a basic theory for the clinical treatment of HFMD.