Novel Small Molecule MWAC-3634 Stabilizes Ebola Entry Protein, Blocks Infection at 0.65 nM
核心洞察
A multi-institutional team discovered MWAC-3634 (搜索), a small molecule that blocks Ebola virus entry by stabilizing the viral entry protein rather than destabilizing it.
Screened from roughly 4.73 billion molecules using DNA-encoded chemistry, the compound inhibited authentic Ebola virus with an IC50 of 0.65 nM.
In a lethal mouse model, 85.7% of orally treated mice survived versus 28.6% of controls, with 100% survival among injected mice.
A University of Minnesota-led multi-institutional research team has discovered a highly potent small molecule that blocks Ebola virus entry by stabilizing the virus's entry protein, providing strong protection when administered orally in a preclinical model. The findings, published in Nature Communications, describe a mechanism that runs counter to all previously structurally characterized small molecules targeting the same protein.
The compound, MWAC-3634 (搜索), targets the Ebola virus entry protein (搜索). Whereas earlier compounds destabilized this protein, MWAC-3634 stabilizes it, preventing the shape changes the virus requires to fuse with and enter a host cell. According to the researchers, it is at least 100 times more potent than previously reported small-molecule Ebola entry inhibitors.
"This compound works in the opposite way from previously studied Ebola entry inhibitors," said Fang Li, PhD, professor of pharmacology at the University of Minnesota Medical School and co-director of the Midwest Antiviral Drug Discovery (AViDD) Center. "Earlier compounds destabilized the Ebola entry protein. MWAC-3634 (搜索) stabilizes it, essentially locking the protein so the virus cannot make the changes required to enter a cell. That reveals a new strategy for blocking infection."
From 4.73 Billion Molecules to a Lead Candidate
The discovery campaign relied on DNA-Encoded Chemistry Technology to screen approximately 4.73 billion molecules directly against the Ebola entry protein, yielding a promising chemical starting point.
"DNA-encoded libraries let us search billions of molecules in a single discovery campaign," said Srinivas Chamakuri, PhD, assistant director of the Center for Drug Discovery in the Department of Pathology at Baylor College of Medicine. "That scale allowed us to explore chemical space far beyond a conventional screen and uncover a promising starting point we might otherwise have missed."
Stereochemical analysis of the initial hit identified MWAC-3634 (搜索) as the most active form. Against authentic Ebola virus, the compound inhibited infection with an IC50 of 0.65 nM and showed no detectable toxicity to cells under the conditions tested.
"The initial hit was only a starting point," said Peter Dosa, PhD, research associate professor of medicinal chemistry at the University of Minnesota. "The starting compound was a mixture of closely related forms. By identifying the most active form, we substantially increased its potency."
Structural Basis for Stabilization
High-resolution structural studies showed that MWAC-3634 (搜索) fits into a pocket in the Ebola entry protein and holds it in a stable state. Normally, the protein must change shape for the virus to fuse with and enter a host cell; locking it in place blocks infection at one of its earliest stages.
"The structure allowed us to see exactly where MWAC-3634 (搜索) binds and how it stabilizes the Ebola entry protein," Li said. "That molecular view helps explain the compound's high potency and gives us a blueprint for designing improved versions."
Oral Protection in a Lethal Mouse Model
In a lethal mouse model, 85.7% of mice treated orally with MWAC-3634 (搜索) survived, compared with 28.6% of controls, while 100% of mice treated by injection survived. Treated animals also showed less weight loss, fewer signs of illness and lower virus levels. The compound demonstrated 69% oral bioavailability relative to intravenous dosing.
"The protection we saw with oral treatment is particularly encouraging," said Robert Davey, PhD, professor of virology, immunology and microbiology and interim director of the National Emerging Infectious Diseases Laboratories at Boston University. "This is still an early-stage compound, and additional development and testing will be needed before we know whether it could be useful in people."
Collaboration and Funding
The study combined DNA-encoded library screening, stereochemical analysis, medicinal chemistry, structural biology, authentic Ebola virus testing, drug exposure studies and animal studies across four institutions: the University of Minnesota, Baylor College of Medicine, Boston University and the University of Florida Scripps Institute (搜索).
Fan Bu is the lead author of the study; Bu, Gang Ye, Kiran L. Sharma and Bruno La Rosa contributed equally to the work. Li is the senior author, and Li, Dosa, Chamakuri and Davey are co-corresponding authors.
The work was supported by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, including the Midwest AViDD Center (U19AI171954), and by NIH grant R01AI195592. MWAC-3634 (搜索) is experimental and has not been approved or shown to prevent or treat Ebola virus disease (搜索) in humans.