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Structural Characterization of Pan-Ebolavirus Antibody 6D6 Targeting the Fusion Peptide of the Surface Glycoprotein.

ABSTRACT: Ebola virus infection causes severe disease in humans and represents a global health threat. Candidates for immunotherapeutics and vaccines have shown promise in clinical trials, although they are ineffective against other members of the Ebolavirus genus that also cause periodic, lethal outbreaks. In this study, we present a crystal structure of a pan-ebolavirus antibody, 6D6, as well as single-particle electron microscopy reconstructions of 6D6 in complex with Ebola and Bundibugyo virus glycoproteins. 6D6 binds to the conserved glycoprotein fusion peptide, implicating it as a site of immune vulnerability that could be exploited to reliably elicit a pan-ebolavirus neutralizing antibody response.

SUBMITTER: Milligan JC

PROVIDER: S-EPMC6325343 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Structural Characterization of Pan-Ebolavirus Antibody 6D6 Targeting the Fusion Peptide of the Surface Glycoprotein.

Milligan Jacob C JC Parekh Diptiben V DV Fuller Katherine M KM Igarashi Manabu M Takada Ayato A Saphire Erica Ollmann EO

The Journal of infectious diseases 20190101 3

Ebola virus infection causes severe disease in humans and represents a global health threat. Candidates for immunotherapeutics and vaccines have shown promise in clinical trials, although they are ineffective against other members of the Ebolavirus genus that also cause periodic, lethal outbreaks. In this study, we present a crystal structure of a pan-ebolavirus antibody, 6D6, as well as single-particle electron microscopy reconstructions of 6D6 in complex with Ebola and Bundibugyo virus glycopr ...[more]

PMID: 30203042

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Project description:The severe death toll caused by the recent outbreak of Ebola virus disease reinforces the importance of developing ebolavirus prevention and treatment strategies. Here, we have explored the immunogenicity of a novel immunization regimen priming with vesicular stomatitis virus particles bearing Sudan Ebola virus (SUDV) glycoprotein (GP) that consists of GP1 & GP2 subunits and boosting with soluble SUDV GP in macaques, which developed robust neutralizing antibody (nAb) responses following immunizations. Moreover, EB46, a protective nAb isolated from one of the immune macaques, is found to target the GP1/GP2 interface, with GP-binding mode and neutralization mechanism similar to a number of ebolavirus nAbs from human and mouse, indicating that the ebolavirus GP1/GP2 interface is a common immunological target in different species. Importantly, selected immune macaque polyclonal sera showed nAb specificity similar to EB46 at substantial titers, suggesting that the GP1/GP2 interface region is a viable target for ebolavirus vaccine.Importance: The elicitation of sustained neutralizing antibody (nAb) responses against diverse ebolavirus strains remains as a high priority for the vaccine field. The most clinically advanced rVSV-ZEBOV vaccine could elicit moderate nAb responses against only one ebolavirus strain, EBOV, among the five ebolavirus strains, which last less than 6 months. Boost immunization strategies are desirable to effectively recall the rVSV vector-primed nAb responses to prevent infections in prospective epidemics, while an in-depth understanding of the specificity of immunization-elicited nAb responses is essential for improving vaccine performance. Here, using non-human primate animal model, we demonstrated that booster immunization with a stabilized trimeric soluble form of recombinant glycoprotein derived from the ebolavirus Sudan strain following the priming rVSV vector immunization led to robust nAb responses that substantially map to the subunit interface of ebolavirus glycoprotein, a common B cell repertoire target of multiple species including primates and rodents.

Project description:Only one naturally occurring human antibody has been described thus far that is capable of potently neutralizing all five ebolaviruses. Here we present two crystal structures of this rare, pan-ebolavirus neutralizing human antibody in complex with Ebola virus and Bundibugyo virus glycoproteins (GPs), respectively. The structures delineate the key protein and glycan contacts for binding that are conserved across the ebolaviruses, explain the antibody's unique broad specificity and neutralization activity, and reveal the likely mechanism behind a known escape mutation in the fusion loop region of GP2. We found that the epitope of this antibody, ADI-15878, extends along the hydrophobic paddle of the fusion loop and then dips down into a highly conserved pocket beneath the N-terminal tail of GP2, a mode of recognition unlike any other antibody elicited against Ebola virus, and likely critical for its broad activity. The fold of Bundibugyo virus glycoprotein, not previously visualized, is similar to the fold of Ebola virus GP, and ADI-15878 binds to each virus's GP with a similar strategy and angle of attack. These findings will be useful in deployment of this antibody as a broad-spectrum therapeutic and in the design of immunogens that elicit the desired broadly neutralizing immune response against all members of the ebolavirus genus and filovirus family.IMPORTANCE There are five different members of the Ebolavirus genus. Provision of vaccines and treatments able to protect against any of the five ebolaviruses is an important goal of public health. Antibodies are a desired result of vaccines and can be delivered directly as therapeutics. Most antibodies, however, are effective against only one or two, not all, of these pathogens. Only one human antibody has been thus far described to neutralize all five ebolaviruses, antibody ADI-15878. Here we describe the molecular structure of ADI-15878 bound to the relevant target proteins of Ebola virus and Bundibugyo virus. We explain how it achieves its rare breadth of activity and propose strategies to design improved vaccines capable of eliciting more antibodies like ADI-15878.

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Dataset Information

Structural Characterization of Pan-Ebolavirus Antibody 6D6 Targeting the Fusion Peptide of the Surface Glycoprotein.

Publications

Structural Characterization of Pan-Ebolavirus Antibody 6D6 Targeting the Fusion Peptide of the Surface Glycoprotein.

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