biostudies-literatureHastie KMUnited States Department of Defense | Defense Advanced Research Projects Agency (DARPA)European Research CouncilNIAID NIH HHSMedical Research CouncilNCI NIH HHSNIH HHSNIGMS NIH HHS1293https://www.ebi.ac.uk/biostudies/studies/S-EPMC11791206biostudies-literatureUnknown16(1)Monoclonal antibodies (mAbs) against Ebola virus (EBOV) glycoprotein (GP<sub>1,2</sub>) are the standard of care for Ebola virus disease (EVD). Anti-GP<sub>1,2</sub> mAbs targeting the stalk and membrane proximal external region (MPER) potently neutralize EBOV in vitro and are protective in a mouse model of EVD. However, their neutralization mechanism is poorly understood because they target a GP<sub>1,2</sub> epitope that has evaded structural characterization. Using X-ray crystallography and cryo-electron tomography of mAb 3A6 complexed with its stalk-MPER epitope, we reveal a previously undescribed mechanism in which 3A6 binds to a conformation of GP<sub>1,2</sub> that is lifted from the virion membrane. We further show that in both domestic guinea pig and rhesus monkey EVD models, 3A6 Nature communicationsAnti-Ebola virus mAb 3A6 protects highly viremic animals from fatal outcome via binding GP<sub>(1,2)</sub> in a position elevated from the virion membrane.PMC11791206P41 GM103393HHSN261201500003I648432U19 AI142790W31P4Q-14-1-001075N91019D00024HHSN261201500003CHHSN272200700016IS10 OD012289HHSN272201400058CMC_UP_1201/16HHSN272201800013CChennareddy CKawaoka YSalie ZLBriggs JAGKuhn JHHastie KMGrinyo AAhmed RWorwa GXiong XNorris MJKe ZHalfmann PJDeWald LEYu XHariharan CHeinrich MSchendel SLCrozier IMcArdle SDavidson EDavis CWHolbrook MRBranco LMDoranz BSaphire EOfalseAnti-Ebola virus mAb 3A6 protects highly viremic animals from fatal outcome via binding GP<sub>(1,2)</sub> in a position elevated from the virion membrane.Monoclonal antibodies (mAbs) against Ebola virus (EBOV) glycoprotein (GP<sub>1,2</sub>) are the standard of care for Ebola virus disease (EVD). Anti-GP<sub>1,2</sub> mAbs targeting the stalk and membrane proximal external region (MPER) potently neutralize EBOV in vitro and are protective in a mouse model of EVD. However, their neutralization mechanism is poorly understood because they target a GP<sub>1,2</sub> epitope that has evaded structural characterization. Using X-ray crystallography and cryo-electron tomography of mAb 3A6 complexed with its stalk-MPER epitope, we reveal a previously undescribed mechanism in which 3A6 binds to a conformation of GP<sub>1,2</sub> that is lifted from the virion membrane. We further show that in both domestic guinea pig and rhesus monkey EVD models, 3A6 2025-01-01T00:00:00Z2025 Feb2026-06-02T02:01:05.724Z2025-04-06T00:24:07.218ZS-EPMC117912063990091110.1038/s41467-025-56452-2