A small molecule inhibits Ebola virus entry through glycoprotein stabilization

Abstract Ebola virus (EBOV) causes outbreaks with high fatality rates, yet potent small-molecule inhibitors targeting EBOV glycoprotein (GP) remain limited. Here, using DNA-encoded chemical libraries, we screen 4.73 billion compounds against EBOV GP and, through stereochemical optimization, identify MWAC-3634. This compound binds GP with high affinity (K d =40.7 nM), potently neutralizes infection (IC₅₀ = 0.65 nM), shows no detectable cytotoxicity, and exhibits favorable pharmacokinetics in mice. This potency substantially exceeds that of known small-molecule inhibitors targeting EBOV GP. Cryo-EM at 2.54 Å resolution reveals that MWAC-3634 occupies a hydrophobic cavity at the GP subunit interface and stabilizes GP, supporting an entry-blocking mechanism distinct from previously described GP-destabilizing inhibitors. In a lethal-challenge mouse model, MWAC-3634 administered either intraperitoneally or orally substantially improves survival and reduces clinical signs. These findings suggest that EBOV GP requires an optimal level of stability for entry, identify GP stabilization as an effective anti-filovirus strategy, and establish MWAC-3634 as a promising lead compound for development.