RESUMO
Antibodies that target the glycan cap epitope on the ebolavirus glycoprotein (GP) are common in the adaptive response of survivors. A subset is known to be broadly neutralizing, but the details of their epitopes and basis for neutralization are not well understood. Here, we present cryoelectron microscopy (cryo-EM) structures of diverse glycan cap antibodies that variably synergize with GP base-binding antibodies. These structures describe a conserved site of vulnerability that anchors the mucin-like domains (MLDs) to the glycan cap, which we call the MLD anchor and cradle. Antibodies that bind to the MLD cradle share common features, including use of IGHV1-69 and IGHJ6 germline genes, which exploit hydrophobic residues and form ß-hairpin structures to mimic the MLD anchor, disrupt MLD attachment, destabilize GP quaternary structure, and block cleavage events required for receptor binding. Our results provide a molecular basis for ebolavirus neutralization by broadly reactive glycan cap antibodies.
Assuntos
Anticorpos Monoclonais/farmacologia , Anticorpos Neutralizantes/farmacologia , Anticorpos Antivirais/farmacologia , Ebolavirus/efeitos dos fármacos , Doença pelo Vírus Ebola/tratamento farmacológico , Proteínas do Envelope Viral/química , Sequência de Aminoácidos , Animais , Anticorpos Monoclonais/química , Anticorpos Monoclonais/metabolismo , Anticorpos Neutralizantes/química , Anticorpos Neutralizantes/metabolismo , Anticorpos Antivirais/química , Anticorpos Antivirais/metabolismo , Especificidade de Anticorpos , Sítios de Ligação , Microscopia Crioeletrônica , Ebolavirus/crescimento & desenvolvimento , Ebolavirus/imunologia , Ebolavirus/patogenicidade , Epitopos/química , Epitopos/imunologia , Feminino , Células HEK293 , Células HeLa , Doença pelo Vírus Ebola/imunologia , Doença pelo Vírus Ebola/patologia , Doença pelo Vírus Ebola/virologia , Humanos , Células Jurkat , Camundongos , Modelos Moleculares , Polissacarídeos/química , Polissacarídeos/imunologia , Ligação Proteica , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Proteínas do Envelope Viral/antagonistas & inibidores , Proteínas do Envelope Viral/genética , Proteínas do Envelope Viral/metabolismoRESUMO
Antibodies targeting the Ebola virus surface glycoprotein (EBOV GP) are implicated in protection against lethal disease, but the characteristics of the human antibody response to EBOV GP remain poorly understood. We isolated and characterized 349 GP-specific monoclonal antibodies (mAbs) from the peripheral B cells of a convalescent donor who survived the 2014 EBOV Zaire outbreak. Remarkably, 77% of the mAbs neutralize live EBOV, and several mAbs exhibit unprecedented potency. Structures of selected mAbs in complex with GP reveal a site of vulnerability located in the GP stalk region proximal to the viral membrane. Neutralizing antibodies targeting this site show potent therapeutic efficacy against lethal EBOV challenge in mice. The results provide a framework for the design of new EBOV vaccine candidates and immunotherapies.
Assuntos
Anticorpos Monoclonais/isolamento & purificação , Anticorpos Neutralizantes/isolamento & purificação , Anticorpos Antivirais/isolamento & purificação , Ebolavirus/imunologia , Doença pelo Vírus Ebola/imunologia , Proteínas do Envelope Viral/imunologia , Animais , Anticorpos Monoclonais/química , Anticorpos Monoclonais/uso terapêutico , Anticorpos Neutralizantes/química , Anticorpos Neutralizantes/uso terapêutico , Anticorpos Antivirais/química , Anticorpos Antivirais/uso terapêutico , Formação de Anticorpos , Complexo Antígeno-Anticorpo/química , República Democrática do Congo/epidemiologia , Surtos de Doenças , Vacinas contra Ebola/imunologia , Vacinas contra Ebola/uso terapêutico , Doença pelo Vírus Ebola/epidemiologia , Doença pelo Vírus Ebola/terapia , Humanos , Imunização Passiva , Camundongos , Sobreviventes , Doadores de Tecidos , Proteínas do Envelope Viral/química , Vírion/imunologiaRESUMO
The mechanisms by which neutralizing antibodies inhibit Marburg virus (MARV) are not known. We isolated a panel of neutralizing antibodies from a human MARV survivor that bind to MARV glycoprotein (GP) and compete for binding to a single major antigenic site. Remarkably, several of the antibodies also bind to Ebola virus (EBOV) GP. Single-particle EM structures of antibody-GP complexes reveal that all of the neutralizing antibodies bind to MARV GP at or near the predicted region of the receptor-binding site. The presence of the glycan cap or mucin-like domain blocks binding of neutralizing antibodies to EBOV GP, but not to MARV GP. The data suggest that MARV-neutralizing antibodies inhibit virus by binding to infectious virions at the exposed MARV receptor-binding site, revealing a mechanism of filovirus inhibition.