RESUMEN
No licensed vaccines or therapies exist for patients infected with Nipah virus (NiV), although an experimental human monoclonal antibody (mAb) cross-reactive to the NiV and Hendra virus (HeV) G glycoprotein, m102.4, has been tested in a phase 1 trial and has been provided under compassionate use for both HeV and NiV exposures. NiV is a highly pathogenic zoonotic paramyxovirus causing regular outbreaks in humans and animals in South and Southeast Asia. The mortality rate of NiV infection in humans ranges from 40% to more than 90%, making it a substantial public health concern. The NiV G glycoprotein mediates host cell attachment, and the F glycoprotein facilitates membrane fusion and infection. We hypothesized that a mAb against the prefusion conformation of the F glycoprotein may confer better protection than m102.4. To test this, two potent neutralizing mAbs against NiV F protein, hu1F5 and hu12B2, were compared in a hamster model. Hu1F5 provided superior protection to hu12B2 and was selected for comparison with m102.4 for the ability to protect African green monkeys (AGMs) from a stringent NiV challenge. AGMs were exposed intranasally to the Bangladesh strain of NiV and treated 5 days after exposure with either mAb (25 milligrams per kilogram). Whereas only one of six AGMs treated with m102.4 survived until the study end point, all six AGMs treated with hu1F5 were protected. Furthermore, a reduced 10 milligrams per kilogram dose of hu1F5 also provided complete protection against NiV challenge, supporting the upcoming clinical advancement of this mAb for postexposure prophylaxis and therapy.
Asunto(s)
Infecciones por Henipavirus , Virus Nipah , Animales , Anticuerpos Monoclonales , Bangladesh , Chlorocebus aethiops , Glicoproteínas/metabolismo , Infecciones por Henipavirus/prevención & control , Primates , Ensayos Clínicos Fase I como AsuntoRESUMEN
Although multiple antigenically distinct ebolavirus species can cause human disease, previous serosurveys focused on only Zaire ebolavirus (EBOV). Thus, the extent of reactivity or exposure to other ebolaviruses, and which sociodemographic factors are linked to this seroreactivity, are unclear. We conducted a serosurvey of 539 healthcare workers (HCW) in Mbandaka, Democratic Republic of the Congo, using ELISA-based analysis of serum IgG against EBOV, Sudan ebolavirus (SUDV) and Bundibugyo ebolavirus (BDBV) glycoproteins (GP). We compared seroreactivity to risk factors for viral exposure using univariate and multivariable logistic regression. Seroreactivity against different GPs ranged from 2.2-4.6%. Samples from six individuals reacted to all three species of ebolavirus and 27 samples showed a species-specific IgG response. We find that community health volunteers are more likely to be seroreactive against each antigen than nurses, and in general, that HCWs with indirect patient contact have higher anti-EBOV GP IgG levels than those with direct contact. Seroreactivity against ebolavirus GP may be associated with positions that offer less occupational training and access to PPE. Those individuals with broadly reactive responses may have had multiple ebolavirus exposures or developed cross-reactive antibodies. In contrast, those individuals with species-specific BDBV or SUDV GP seroreactivity may have been exposed to an ebolavirus not previously known to circulate in the region.
Asunto(s)
Ebolavirus , Fiebre Hemorrágica Ebola , Anticuerpos Antivirales , República Democrática del Congo/epidemiología , Glicoproteínas , Personal de Salud , Humanos , Inmunoglobulina GRESUMEN
Hendra virus and Nipah virus (NiV), members of the Henipavirus (HNV) genus, are zoonotic paramyxoviruses known to cause severe disease across six mammalian orders, including humans. We isolated a panel of human monoclonal antibodies (mAbs) from the B cells of an individual with prior exposure to equine Hendra virus (HeV) vaccine, targeting distinct antigenic sites. The most potent class of cross-reactive antibodies achieves neutralization by blocking viral attachment to the host cell receptors ephrin-B2 and ephrin-B3, with a second class being enhanced by receptor binding. mAbs from both classes display synergistic activity in vitro. In a stringent hamster model of NiV Bangladesh (NiVB) infection, antibodies from both classes reduce morbidity and mortality and achieve synergistic protection in combination. These candidate mAbs might be suitable for use in a cocktail therapeutic approach to achieve synergistic potency and reduce the risk of virus escape.
Asunto(s)
Anticuerpos Monoclonales/farmacología , Anticuerpos Neutralizantes/farmacología , Antivirales/farmacología , Efrina-B2/antagonistas & inhibidores , Efrina-B3/antagonistas & inhibidores , Infecciones por Henipavirus/prevención & control , Henipavirus/patogenicidad , Receptores Virales/antagonistas & inhibidores , Animales , Especificidad de Anticuerpos , Chlorocebus aethiops , Reacciones Cruzadas , Modelos Animales de Enfermedad , Quimioterapia Combinada , Efrina-B2/inmunología , Efrina-B2/metabolismo , Efrina-B3/inmunología , Efrina-B3/metabolismo , Femenino , Infecciones por Henipavirus/inmunología , Infecciones por Henipavirus/metabolismo , Infecciones por Henipavirus/virología , Interacciones Huésped-Patógeno , Humanos , Mesocricetus , Receptores Virales/inmunología , Receptores Virales/metabolismo , Células VeroRESUMEN
Hendra virus (HeV) and Nipah virus (NiV) are henipaviruses (HNVs) causing respiratory illness and severe encephalitis in humans, with fatality rates of 50-100%. There are no licensed therapeutics or vaccines to protect humans. HeV and NiV use a receptor-binding glycoprotein (G) and a fusion glycoprotein (F) to enter host cells. HNV F and G are the main targets of the humoral immune response, and the presence of neutralizing antibodies is a correlate of protection against NiV and HeV in experimentally infected animals. We describe here two cross-reactive F-specific antibodies, 1F5 and 12B2, that neutralize NiV and HeV through inhibition of membrane fusion. Cryo-electron microscopy structures reveal that 1F5 and 12B2 recognize distinct prefusion-specific, conserved quaternary epitopes and lock F in its prefusion conformation. We provide proof-of-concept for using antibody cocktails for neutralizing NiV and HeV and define a roadmap for developing effective countermeasures against these highly pathogenic viruses.
Asunto(s)
Anticuerpos Antivirales/inmunología , Anticuerpos ampliamente neutralizantes/inmunología , Virus Hendra/inmunología , Virus Nipah/inmunología , Proteínas Virales de Fusión/inmunología , Animales , Anticuerpos Monoclonales Humanizados/inmunología , Células CHO , Cricetulus , Reacciones Cruzadas , Células HEK293 , Infecciones por Henipavirus/inmunología , Infecciones por Henipavirus/prevención & control , Humanos , Ratones , Internalización del VirusRESUMEN
Three Ebolavirus genus viruses cause lethal disease and lack targeted therapeutics: Ebola virus, Sudan virus and Bundibugyo virus. Monoclonal antibody (mAb) cocktails against the surface glycoprotein (GP) present a potential therapeutic strategy. Here we report two crystal structures of the antibody BDBV223, alone and complexed with its GP2 stalk epitope, an interesting site for therapeutic/vaccine design due to its high sequence conservation among ebolaviruses. BDBV223, identified in a human survivor of Bundibugyo virus disease, neutralizes both Bundibugyo virus and Ebola virus, but not Sudan virus. Importantly, the structure suggests that BDBV223 binding interferes with both the trimeric bundle assembly of GP and the viral membrane by stabilizing a conformation in which the monomers are separated by GP lifting or bending. Targeted mutagenesis of BDBV223 to enhance SUDV GP recognition indicates that additional determinants of antibody binding likely lie outside the visualized interactions, and perhaps involve quaternary assembly or membrane-interacting regions.
Asunto(s)
Anticuerpos Monoclonales/inmunología , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Ebolavirus/efectos de los fármacos , Fiebre Hemorrágica Ebola/inmunología , Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/aislamiento & purificación , Anticuerpos Monoclonales/metabolismo , Anticuerpos Neutralizantes/química , Anticuerpos Neutralizantes/aislamiento & purificación , Anticuerpos Neutralizantes/metabolismo , Anticuerpos Antivirales/química , Anticuerpos Antivirales/aislamiento & purificación , Anticuerpos Antivirales/metabolismo , Reacciones Cruzadas/inmunología , Cristalografía por Rayos X , Ebolavirus/inmunología , Epítopos/química , Epítopos/inmunología , Fiebre Hemorrágica Ebola/sangre , Fiebre Hemorrágica Ebola/virología , Humanos , Hibridomas , Mutagénesis , Sobrevivientes , Proteínas del Envoltorio Viral/química , Proteínas del Envoltorio Viral/inmunología , Proteínas del Envoltorio Viral/metabolismoRESUMEN
The structural features that govern broad-spectrum activity of broadly neutralizing anti-ebolavirus antibodies (Abs) outside of the internal fusion loop epitope are currently unknown. Here we describe the structure of a broadly neutralizing human monoclonal Ab (mAb), ADI-15946, which was identified in a human survivor of the 2013-2016 outbreak. The crystal structure of ADI-15946 in complex with cleaved Ebola virus glycoprotein (EBOV GPCL) reveals that binding of the mAb structurally mimics the conserved interaction between the EBOV GP core and its glycan cap ß17-ß18 loop to inhibit infection. Both endosomal proteolysis of EBOV GP and binding of mAb FVM09 displace this loop, thereby increasing exposure of ADI-15946's conserved epitope and enhancing neutralization. Our work also mapped the paratope of ADI-15946, thereby explaining reduced activity against Sudan virus, which enabled rational, structure-guided engineering to enhance binding and neutralization of Sudan virus while retaining the parental activity against EBOV and Bundibugyo virus.
Asunto(s)
Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Ebolavirus/inmunología , Proteínas Virales de Fusión/inmunología , Anticuerpos Monoclonales/inmunología , Afinidad de Anticuerpos/inmunología , Cristalografía por Rayos X , Humanos , Estructura Terciaria de Proteína , SobrevivientesRESUMEN
Filoviruses are the causative agents of highly lethal outbreaks in sub-Saharan Africa. Although an experimental vaccine and several therapeutics are being deployed in the Democratic Republic of Congo to combat the ongoing Ebola virus outbreak, these therapies are specific for only one filovirus species. There is currently significant interest in developing broadly reactive monoclonal antibodies (mAbs) with utility against the variety of ebolaviruses that may emerge. Thus far, the primary target of these mAbs has been the viral spike glycoprotein (GP). Here we present an overview of GP-targeted antibodies that exhibit broad reactivity and the structural characteristics that could confer this cross-reactivity. We also discuss how these structural features could be leveraged to design vaccine antigens that elicit cross-reactive antibodies.
Asunto(s)
Anticuerpos Antivirales/inmunología , Reacciones Cruzadas , Ebolavirus/inmunología , Epítopos/inmunología , Proteínas del Envoltorio Viral/inmunología , Animales , Anticuerpos Neutralizantes/inmunología , Fiebre Hemorrágica Ebola/inmunología , Fiebre Hemorrágica Ebola/virología , HumanosRESUMEN
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.
Asunto(s)
Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Ebolavirus/inmunología , Glicoproteínas/inmunología , Epítopos/inmunología , Humanos , Conformación Proteica , Proteínas del Envoltorio Viral/inmunologíaRESUMEN
Filoviruses, including ebolaviruses and marburgviruses, are the causative agents of highly lethal disease outbreaks. The 2013-2016 Ebola virus outbreak was responsible for >28000 infections and >11000 deaths. Although there are currently no licensed vaccines or therapeutics for any filovirus-induced disease, monoclonal antibodies (mAbs) are among the most promising options for therapeutic development. Hundreds of mAbs have been isolated from human survivors of filovirus infections that target the viral spike glycoprotein (GP). The binding, neutralization, and cross-reactivity of many of these mAbs has been determined. Several mAbs have been characterized structurally, and this information has been crucial for strategizing therapeutic and vaccine design. Here we present an overview of the structural features of the neutralizing/protective epitopes on filovirus glycoproteins.
Asunto(s)
Infecciones por Filoviridae/inmunología , Filoviridae/inmunología , Vacunas Virales/inmunología , Animales , Anticuerpos Monoclonales/metabolismo , Anticuerpos Neutralizantes/metabolismo , Anticuerpos Antivirales/metabolismo , Bases de Datos de Proteínas , Epítopos de Linfocito B/inmunología , Infecciones por Filoviridae/terapia , Humanos , Conformación Proteica , Proteínas Virales/inmunologíaRESUMEN
The X-ray crystal structure of the Lymphocytic choriomeningitis virus nucleoprotein C-terminal immunosuppressive domain (LCMV NPΔ340) was determined to 2.0â Å resolution. The structure indicates that LCMV NPΔ340, like the other structurally characterized arenaviral nucleoproteins, adopts the fold of an exonuclease. This structure provides a crucial three-dimensional template for functional exploration of the replication and immunosuppression of this prototypic arenavirus.