Drug-based Anti-filamentous Virus And Anti-Nipa Virus Drug Discovery

Both filovirus and nipah virus (NiV) are severe viruses which are lethal to human and damage public safety. Filovirus and NiV infection cause human hemorrhagic fever and severe encephalitis rapidly with high rate fatality. Furthermore, there is neither drug nor vaccine available. Drug development to filovirus and NiV will benefit not only people in epidemic areas, such as Africa and Southeast Asia, but also recruit our antivirus drug stock.Filovirus includes Ebola virus (EBOV) and Marburg virus (MARV). EBOV and MARV infection cause ebola hemorrhagic fever (EHF) and Marburg hemorrhagic fever (MHF), of which EHF is more deadly. NiV infection causes severe viral encephalitis and respiratory disease with high fatality rate. Fliovirus and NiV require biosafety level 4 (BSL-4) facilities to carry experiments with live virus, which restricts their drug development.Both filovirus and nipah virus belong to enveloped virus. The virus envelope consists lipid and protein which come from the host cells membrane. The envelope glycoproteins involve in viral entry host cells process. First, the host receptors are recognized and bound by viral GP, whereafter, the fusion occurs upon viral envelop and host cell membrane. Filovirus GP is responsible for this step; for NiV, G and F are involved in viral entry. Virus entry into cells is the first step of infection which makes it a useful target for antiviral drug development.The application of drug repositioning in the development of anti-infective drugs has been recognized widely. Due to the safety and side effects of listed drugs have been clarified, GMP is available as well, it is possible to find anti-filoviruses drugs and/or anti-nipah virus drugs within short time. Pseudoviruses are widely used for highly pathogenic viruses study. We used a cell-based pseudotyped system for flilovirus and nipah virus drug screening:, an HIV-1-luc core packed with filoviruses virus glycoprotein, including Zaire Ebola virus (ZEBOV-GP/HIV-1-luc)、Sudan Ebola virus (SEBOV-GP/HIV-1-luc) and Marburg virus (MARV-GP/HIV-1-luc), as well as by nipah virus glycoprotein F and G (NiV-F-G/HIV-1-luc).First, the ZEBOV-GP/HIV-1-luc was used to screen 840 listed drugs, and the results showed that there were 12 gonadal hormone drugs having inhibitory activities on ZEBOV-GP/HIV-1-luc entry at final concentration of 10μmol·L-1. Among them, three drugs, toremifene citrate (IC50:0.19±0.02μmol·L-1), tamoxifen citrate (IC50:0.32±0.01 μmol·L-1) and clomiphene citrate (IC50:0.53±0.02μmol·L-1), showed strong activities with IC50<1μmol·L-1; including seven drugs, estradiol benzoate (IC50:1.83±5.69 μmol·L-1), raloxifene hydrochloride (IC50:3.48±0.07μmol·L-1), equilin (IC50:4.00± 9.94μmol·L-1), estradiol (IC50:5.26±9.92μmol·L-1), quinestrol (IC50:6.36±5.37 μmol·L-1), estrone (IC50:6.87±0.03μmol·L-1) and finasteride (IC50:9.94± 0.45μmol·L-1), had moderate activities with IC50 between 1μmol·L-1 and 10μmol·L-1; and hexestrol (IC50:14.20±0.55μmol·L-1) and chlormadinone acetate (IC50:24.60± 0.36μmol·L-1) also had weak activities against ZEBOV. Further study showed that toremifene citrate, tamoxifen citrate, clomiphene citrate, raloxifene hydrochloride and quinestrol could block both SEBOV-GP/HIV-1-luc and MARV-GP/HIV-1-luc entries.We also used NiV-F-G/HIV-1-luc to screen 1300 listed drugs. To improve viral infectivity, the plasmid ephrin-B2 (EFNB2) was transfected into 293T cells to obtain EFNB2 overexpressed 293T cells as infected cells. The results showed among 1300 drug, none could block nipah virus entry at final concentration of 10μM.As the summary, we prepared recombinant filovirus and nipah virus to evaluate the 840 and 1300 listed drugs, respectively. The results showed that 5 gonadal hormone drugs have broad spectrum anti-filovirus inhibitory activity. None among 1300 approved drugs showed inhibitory effect on nipah virus entry. This study can provide experimental data for the anti-filovirus/nipah drugs development from approved drugs.