Identification of clinical candidates against West Nile virus by activity screening in vitro and effect evaluation in vivo.

The West Nile virus (WNV) is a member of the flavivirus and is known to cause encephalitis. There is currently no specific treatment for WNV infection. Repurposing of clinically approved drugs appeared promising for rapidly identifying effective, safe, and readily available candidates for antiviral drugs. Here, we screened the small-molecule compounds with anti-WNV activity from 978 Food Drug Administration-approved drugs. Four compounds, including cilnidipine, mycophenolate mofetil, nitazoxanide, and teriflunomide, were found to efficiently abrogate WNV infection in Vero cells and human neuroblastoma SH-SY5Y cells. The four compounds also exert broad-spectrum antiviral activity against the Zika virus, Japanese encephalitis virus, yellow fever virus, tick-borne encephalitis virus, and chikungunya virus. Furthermore, nitazoxanide (a synthetic benzamide) and teriflunomide (an inhibitor of dihydroorotate dehydrogenase, DHODH) protected 20% and 40% of mice from lethal WNV challenge, respectively. Both drugs, which are orally bioavailable and have been approved clinically for many years, may be promising therapeutics for WNV infection. Moreover, the other two DHODH inhibitors, ML390 and vidofludimus, also displayed potent activity against WNV infection in vitro and in vivo.