Griffithsin (GRFT) is a broad-spectrum antiviral protein that is effective against several glycosylated viruses. Here, we have evaluated the in vitro and in vivo antiviral activities of GRFT against Japanese encephalitis virus (JEV) infection. In vitro experiments showed that treatment of JEV with GRFT before inoculation of BHK-21 cells inhibited infection in a dose-dependent manner, with 99 % inhibition at 100 μg/ml and a 50 % inhibitory concentration (IC(50)) of 265 ng/ml (20 nM). Binding assays suggested that binding of GRFT to JEV virions inhibited JEV infection. In vivo experiment showed that GRFT (5 mg/kg) administered intraperitoneally before virus infection could completely prevent mortality in mice challenged intraperitoneally with a lethal dose of JEV. Our study also suggested that GRFT prevents JEV infection at the entry phase by targeting the virus. Collectively, our data demonstrate that GRFT is an antiviral agent with potential application in the development of therapeutics against JEV or other flavivirus infections.

The unfolded protein response (UPR) is cyto-protective machinery elicited towards an influx of large amount of protein synthesis in the endoplasmic reticulum (ER). Extensive studies suggest that the UPR can also be activated during virus infection. In the present studies, we first evaluated if porcine epidemic diarrhea virus (PEDV) infection activated the UPR pathways. Electron microscopy analysis demonstrated the morphology changes of ER post-PEDV infection. Western blot and real-time PCR identified the differences of UPR genes in response to PEDV infection. The results suggested that PEDV infection induced UPR in Vero cells. Meanwhile, we silenced the expression of PKR-like ER kinase (PERK) by shRNA, we found that the knockdown of PERK increased virus loads in the cells, which was consistent with the result on 4-phenylbutyrate (4-PBA) treatment. We next determined whether 2-Deoxy-d-glucose (2-DG), an ER stress inducer, possessed antiviral activity against PEDV infection. Plaque formation assay, RT-PCR and Western blot analysis suggested that 2-DG might inhibit virus infection by affecting viral protein translation during the early stage of virus infection. Interestingly, we also found that 2-DG treatment could affect virus assembly, which is similar to previous studies on influenza virus. All these results support the therapeutic potential of using 2-DG or glucose/mannose analogs to induce the UPR to block virus replication.

No abstract

No abstract

It is well known that many viruses use heparan sulfate as the initial attachment factor. In the present study, we determined whether porcine epidemic diarrhea virus (PEDV), an emerging veterinary virus, infects Vero cells by attaching to heparan sulfate. Western blot analysis, real-time PCR, and plaque formation assay revealed that PEDV infection was inhibited when the virus was pretreated with heparin (an analogue of heparan sulfate). There was no inhibitory effect when the cells were pre-incubated with heparin. We next demonstrated that enzymatic removal of the highly sulfated domain of heparan sulfate by heparinase I treatment inhibited PEDV infection. We also confirmed that sodium chlorate, which interferes with heparan sulfate biosynthesis, also inhibited PEDV infection. Furthermore, we examined the effect of two heparin derivatives with different types of sulfation on PEDV infection. The data suggested de-N-sulfated heparin, but not N-acetyl-de-O-sulfated heparin, inhibits PEDV infection. In summary, our studies revealed that heparan sulfate acts as the attachment factor of PEDV in Vero cells.

No abstract

No abstract

No abstract