RESUMEN
Several ebolaviruses cause outbreaks of severe disease. Vaccines and monoclonal antibody cocktails are available to treat Ebola virus (EBOV) infections, but not Sudan virus (SUDV) or other ebolaviruses. Current cocktails contain antibodies that cross-react with the secreted soluble glycoprotein (sGP) that absorbs virus-neutralizing antibodies. By sorting memory B cells from EBOV infection survivors, we isolated two broadly reactive anti-GP monoclonal antibodies, 1C3 and 1C11, that potently neutralize, protect rodents from disease, and lack sGP cross-reactivity. Both antibodies recognize quaternary epitopes in trimeric ebolavirus GP. 1C11 bridges adjacent protomers via the fusion loop. 1C3 has a tripartite epitope in the center of the trimer apex. One 1C3 antigen-binding fragment anchors simultaneously to the three receptor-binding sites in the GP trimer, and separate 1C3 paratope regions interact differently with identical residues on the three protomers. A cocktail of both antibodies completely protected nonhuman primates from EBOV and SUDV infections, indicating their potential clinical value.
Asunto(s)
Anticuerpos Neutralizantes , Anticuerpos Antivirales , Ebolavirus , Fiebre Hemorrágica Ebola , Animales , Epítopos , Glicoproteínas/química , Subunidades de ProteínaRESUMEN
Lassa virus (LASV) causes hemorrhagic fever and is endemic in West Africa. Protective antibody responses primarily target the LASV surface glycoprotein (GPC), and GPC-B competition group antibodies often show potent neutralizing activity in humans. However, which features confer potent and broadly neutralizing antibody responses is unclear. Here, we compared three crystal structures of LASV GPC complexed with GPC-B antibodies of varying neutralization potency. Each GPC-B antibody recognized an overlapping epitope involved in binding of two adjacent GPC monomers and preserved the prefusion trimeric conformation. Differences among GPC-antibody interactions highlighted specific residues that enhance neutralization. Using structure-guided amino acid substitutions, we increased the neutralization potency and breadth of these antibodies to include all major LASV lineages. The ability to define antibody residues that allow potent and broad neutralizing activity, together with findings from analyses of inferred germline precursors, is critical to develop potent therapeutics and for vaccine design and assessment.
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Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Células Germinativas/inmunología , Fiebre de Lassa/inmunología , Virus Lassa/inmunología , Glicoproteínas de Membrana/química , Proteínas del Envoltorio Viral/química , Animales , Antígenos Virales/inmunología , Chlorocebus aethiops , Drosophila/citología , Epítopos/química , Epítopos/inmunología , Células HEK293 , Humanos , Fiebre de Lassa/virología , Glicoproteínas de Membrana/inmunología , Estructura Secundaria de Proteína , Células Vero , Proteínas del Envoltorio Viral/inmunología , Vacunas Virales/inmunologíaRESUMEN
The 2013-2015 West African epidemic of Ebola virus disease (EVD) reminds us of how little is known about biosafety level 4 viruses. Like Ebola virus, Lassa virus (LASV) can cause hemorrhagic fever with high case fatality rates. We generated a genomic catalog of almost 200 LASV sequences from clinical and rodent reservoir samples. We show that whereas the 2013-2015 EVD epidemic is fueled by human-to-human transmissions, LASV infections mainly result from reservoir-to-human infections. We elucidated the spread of LASV across West Africa and show that this migration was accompanied by changes in LASV genome abundance, fatality rates, codon adaptation, and translational efficiency. By investigating intrahost evolution, we found that mutations accumulate in epitopes of viral surface proteins, suggesting selection for immune escape. This catalog will serve as a foundation for the development of vaccines and diagnostics. VIDEO ABSTRACT.
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Genoma Viral , Fiebre de Lassa/virología , Virus Lassa/genética , ARN Viral/genética , África Occidental/epidemiología , Animales , Evolución Biológica , Reservorios de Enfermedades , Ebolavirus/genética , Variación Genética , Glicoproteínas/genética , Fiebre Hemorrágica Ebola/virología , Humanos , Fiebre de Lassa/epidemiología , Fiebre de Lassa/transmisión , Virus Lassa/clasificación , Virus Lassa/fisiología , Murinae/genética , Mutación , Nigeria/epidemiología , Proteínas Virales/genética , Zoonosis/epidemiología , Zoonosis/virologíaRESUMEN
There are no approved treatments for Lassa fever (LF), which is responsible for thousands of deaths each year in West Africa. A major challenge in developing effective medical countermeasures against LF is the high diversity of circulating Lassa virus (LASV) strains with four recognized lineages and four proposed lineages. The recent resurgence of LASV in Nigeria caused by genetically distinct strains underscores this concern. Two LASV lineages (II and III) are dominant in Nigeria. Here, we show that combinations of two or three pan-lineage neutralizing human monoclonal antibodies (8.9F, 12.1F, 37.D) known as Arevirumab-2 or Arevirumab-3 can protect up to 100% of cynomolgus macaques against challenge with both lineage II and III LASV isolates when treatment is initiated at advanced stages of disease on day 8 after LASV exposure. This work demonstrates that it may be possible to develop postexposure interventions that can broadly protect against most strains of LASV.
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Fiebre de Lassa , Virus Lassa , Animales , Humanos , Fiebre de Lassa/prevención & control , África Occidental , Anticuerpos Monoclonales , Anticuerpos Neutralizantes , Macaca fascicularisRESUMEN
BACKGROUND: Ebola virus disease (EVD) is a severe viral illness caused by Ebola virus (EBOV). The 2013-2016 EVD outbreak in West Africa is the largest recorded, with >11 000 deaths. Development of the ReEBOV Antigen Rapid Test (ReEBOV RDT) was expedited to provide a point-of-care test for suspected EVD cases. METHODS: Recombinant EBOV viral protein 40 antigen was used to derive polyclonal antibodies for RDT and enzyme-linked immunosorbent assay development. ReEBOV RDT limits of detection (LOD), specificity, and interference were analytically validated on the basis of Food and Drug Administration (FDA) guidance. RESULTS: The ReEBOV RDT specificity estimate was 95% for donor serum panels and 97% for donor whole-blood specimens. The RDT demonstrated sensitivity to 3 species of Ebolavirus (Zaire ebolavirus, Sudan ebolavirus, and Bundibugyo ebolavirus) associated with human disease, with no cross-reactivity by pathogens associated with non-EBOV febrile illness, including malaria parasites. Interference testing exhibited no reactivity by medications in common use. The LOD for antigen was 4.7 ng/test in serum and 9.4 ng/test in whole blood. Quantitative reverse transcription-polymerase chain reaction testing of nonhuman primate samples determined the range to be equivalent to 3.0 × 105-9.0 × 108 genomes/mL. CONCLUSIONS: The analytical validation presented here contributed to the ReEBOV RDT being the first antigen-based assay to receive FDA and World Health Organization emergency use authorization for this EVD outbreak, in February 2015.
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Antígenos Virales/sangre , Brotes de Enfermedades , Ebolavirus/inmunología , Fiebre Hemorrágica Ebola/diagnóstico , Sistemas de Atención de Punto , Proteínas de la Matriz Viral/sangre , África Occidental/epidemiología , Animales , Ebolavirus/aislamiento & purificación , Ensayo de Inmunoadsorción Enzimática , Fiebre Hemorrágica Ebola/virología , Humanos , Inmunoensayo , Límite de Detección , Juego de Reactivos para Diagnóstico , Sensibilidad y EspecificidadRESUMEN
BACKGROUND: Throughout the 2014-2015 Ebola outbreak in West Africa, major gaps were exposed in the availability of validated rapid diagnostic platforms, protective vaccines, and effective therapeutic agents. These gaps potentiated the development of prototype rapid lateral flow immunodiagnostic (LFI) assays that are true point-of-contact platforms, for the detection of active Ebola infections in small blood samples. METHODS: Recombinant Ebola and Marburg virus matrix VP40 and glycoprotein (GP) antigens were used to derive a panel of monoclonal and polyclonal antibodies. Antibodies were tested using a multivariate approach to identify antibody-antigen combinations suitable for enzyme-linked immunosorbent assay (ELISA) and LFI assay development. RESULTS: Polyclonal antibodies generated in goats were superior reagents for capture and detection of recombinant VP40 in test sample matrices. These antibodies were optimized for use in antigen-capture ELISA and LFI assay platforms. Prototype immunoglobulin M (IgM)/immunoglobulin G (IgG) ELISAs were similarly developed that specifically detect Ebola virus-specific antibodies in the serum of experimentally infected nonhuman primates and in blood samples obtained from patients with Ebola from Sierra Leone. CONCLUSIONS: The prototype recombinant Ebola LFI assays developed in these studies have sensitivities that are useful for clinical diagnosis of acute ebolavirus infections. The antigen-capture and IgM/IgG ELISAs provide additional confirmatory assay platforms for detecting VP40 and other ebolavirus-specific immunoglobulins.
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Antígenos Virales/inmunología , Filoviridae/inmunología , Inmunoensayo/métodos , África Occidental , Animales , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/inmunología , Reacciones Cruzadas/inmunología , Ebolavirus/inmunología , Ensayo de Inmunoadsorción Enzimática/métodos , Fiebre Hemorrágica Ebola/sangre , Fiebre Hemorrágica Ebola/inmunología , Fiebre Hemorrágica Ebola/virología , Humanos , Inmunoglobulina G/sangre , Inmunoglobulina G/inmunología , Inmunoglobulina M/sangre , Inmunoglobulina M/inmunología , Enfermedad del Virus de Marburg/sangre , Enfermedad del Virus de Marburg/inmunología , Enfermedad del Virus de Marburg/virología , Marburgvirus/inmunología , Sierra LeonaRESUMEN
BACKGROUND: The Department of Defense (DoD) and the Food and Drug Administration (FDA) have collaboratively worked on a pre-Emergency Use Authorization (pre-EUA) process for in vitro diagnostic (IVD) devices, using FDA's regulatory flexibilities under the EUA authorities. The pre-EUA process enables FDA review of data in anticipation of a request for an EUA, advancing US government public health emergency preparedness efforts. METHODS: The IVD device developed to detect Escherichia coli O104:H4, for which an EUA has not been issued, serves as an example to illustrate that process. Specifically, DoD designed real-time PCR assays to target the virulent E. coli strain O104:H4 (etiological agent of the 2011 German outbreak) including: fliC (flagellin), Agg3C (AAF), and rfb (wbwC) on the basis of the published sequences. RESULTS: After development and optimization of these 3 specific assays, a defined protocol was followed to determine and document the sensitivity and specificity of each assay analytically. CONCLUSIONS: FDA reviewed these data and returned commentary on additional required experiments to complete the pre-EUA process and expedite the use of the device should there be an emergency need for an IVD device to detect this virulent E. coli strain before such a test is cleared by FDA.
Asunto(s)
Infecciones por Escherichia coli/diagnóstico , Infecciones por Escherichia coli/microbiología , Escherichia coli/aislamiento & purificación , Reacción en Cadena en Tiempo Real de la Polimerasa/instrumentación , ADN Bacteriano/genética , Brotes de Enfermedades , Escherichia coli/genética , Proteínas de Escherichia coli/genética , Proteínas Fimbrias/genética , Flagelina/genética , Galactosiltransferasas/genética , Humanos , Hidrólisis , Límite de Detección , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Análisis de Secuencia de ADN , Estados Unidos , United States Food and Drug AdministrationRESUMEN
Lassa fever (LF) is an acute viral illness that causes thousands of deaths annually in West Africa. There are currently no Lassa virus (LASV) vaccines or antivirals approved for human use. Recently, we showed that combinations of broadly neutralizing human monoclonal antibodies (BNhuMAbs) known as Arevirumab-2 or Arevirumab-3 protected up to 100% of cynomolgus macaques against challenge with diverse lineages of LASV when treatment was initiated at advanced stages of disease. This previous work assessed efficacy against parenteral exposure. However, transmission of LASV to humans occurs primarily by mucosal exposure to virus shed from Mastomys rodents. Here, we describe the development of a lethal intranasal exposure macaque model of LF. This model is employed to show that Arevirumab cocktails rescue 100% of macaques from lethal LASV infection when treatment is initiated 8 days after LASV exposure. Our work demonstrates BNhuMAbs have utility in treating LASV infection acquired through mucosal exposure.
Asunto(s)
Fiebre de Lassa , Virus Lassa , Animales , Humanos , Fiebre de Lassa/tratamiento farmacológico , Fiebre de Lassa/prevención & control , Macaca fascicularis , Inmunoterapia , Anticuerpos Monoclonales/farmacología , Anticuerpos Monoclonales/uso terapéuticoRESUMEN
Lassa virus (LASV) is a World Health Organization (WHO) priority pathogen that causes high morbidity and mortality. Recently, we showed that a combination of three broadly neutralizing human monoclonal antibodies known as Arevirumab-3 (8.9F, 12.1F, 37.2D) based on the lineage IV Josiah strain protected 100% of cynomolgus macaques against heterologous challenge with lineage II and III strains of LASV when therapy was initiated beginning at day 8 after challenge. LASV strains from Benin and Togo represent a new lineage VII that are more genetically diverse from lineage IV than strains from lineages II and III. Here, we tested the ability of Arevirumab-3 to protect macaques against a LASV lineage VII Togo isolate when treatment was administered beginning 8 days after exposure. Unexpectedly, only 40% of treated animals survived challenge. In a subsequent study we showed that Arevirumab-3 protected 100% of macaques from lethal challenge when treatment was initiated 7 days after LASV Togo exposure. Based on our transcriptomics data, successful Arevirumab-3 treatment correlated with diminished neutrophil signatures and the predicted development of T cell responses. As the in vitro antiviral activity of Arevirumab-3 against LASV Togo was equivalent to lineage II and III strains, the reduced protection in macaques against Togo likely reflects the faster disease course of LASV Togo in macaques than other strains. This data causes concern regarding the ability of heterologous vaccines and treatments to provide cross protection against lineage VII LASV isolates.
Asunto(s)
Fiebre de Lassa , Virus Lassa , Humanos , Animales , Virulencia , Macaca fascicularis , Anticuerpos Monoclonales/farmacologíaRESUMEN
Monoclonal antibodies (mAbs) against Ebola virus (EBOV) glycoprotein (GP1,2) are the standard of care for Ebola virus disease (EVD). Anti-GP1,2 mAbs targeting the stalk and membrane proximal external region (MPER) potently neutralize EBOV in vitro. However, their neutralization mechanism is poorly understood because they target a GP1,2 epitope that has evaded structural characterization. Moreover, their in vivo efficacy has only been evaluated in the mouse model of EVD. Using x-ray crystallography and cryo-electron tomography of 3A6 complexed with its stalk- GP1,2 MPER epitope we reveal a novel mechanism in which 3A6 elevates the stalk or stabilizes a conformation of GP1,2 that is lifted from the virion membrane. In domestic guinea pig and rhesus monkey EVD models, 3A6 provides therapeutic benefit at high viremia levels, advanced disease stages, and at the lowest dose yet demonstrated for any anti-EBOV mAb-based monotherapy. These findings can guide design of next-generation, highly potent anti-EBOV mAbs.
RESUMEN
Developing potent therapeutics and effective vaccines are the ultimate goals in controlling infectious diseases. Lassa virus (LASV), the causative pathogen of Lassa fever (LF), infects hundreds of thousands annually, but effective antivirals or vaccines against LASV infection are still lacking. Furthermore, neutralizing antibodies against LASV are rare. Here, we describe biochemical analyses and high-resolution cryo-electron microscopy structures of a therapeutic cocktail of three broadly protective antibodies that target the LASV glycoprotein complex (GPC), previously identified from survivors of multiple LASV infections. Structural and mechanistic analyses reveal compatible neutralizing epitopes and complementary neutralization mechanisms that offer high potency, broad range, and resistance to escape. These antibodies either circumvent or exploit specific glycans comprising the extensive glycan shield of GPC. Further, they require mammalian glycosylation, native GPC cleavage, and proper GPC trimerization. These findings guided engineering of a next-generation GPC antigen suitable for future neutralizing antibody and vaccine discovery. Together, these results explain protective mechanisms of rare, broad, and potent antibodies and identify a strategy for the rational design of therapeutic modalities against LF and related infectious diseases.
Asunto(s)
Fiebre de Lassa , Vacunas Virales , Animales , Humanos , Virus Lassa , Microscopía por Crioelectrón , Anticuerpos Neutralizantes , Epítopos , Glicoproteínas , Polisacáridos , Antivirales , MamíferosRESUMEN
Lassa fever (LF) is a viral hemorrhagic disease found in Sub-Saharan Africa and is responsible for up to 300,000 cases and 5000 deaths annually. LF is highly endemic in Sierra Leone, particularly in its Eastern Province. Kenema Government Hospital (KGH) maintains one of only a few LF isolation facilities in the world with year-round diagnostic testing. Here we focus on space-time trends for LF occurring in Sierra Leone between 2012 and 2019 to provide a current account of LF in the wake of the 2014-2016 Ebola epidemic. Data were analyzed for 3277 suspected LF cases and classified as acute, recent, and non-LF or prior LF exposure using enzyme-linked immunosorbent assays (ELISAs). Presentation rates for acute, recent, and non-LF or prior LF exposure were 6.0% (195/3277), 25.6% (838/3277), and 68.4% (2244/3277), respectively. Among 2051 non-LF or prior LF exposures, 33.2% (682/2051) tested positive for convalescent LF exposure. The overall LF case-fatality rate (CFR) was 78.5% (106/135). Both clinical presentations and confirmed LF cases declined following the Ebola epidemic. These declines coincided with an increased duration between illness onset and clinical presentation, perhaps suggesting more severe disease or presentation at later stages of illness. Acute LF cases and their corresponding CFRs peaked during the dry season (November to April). Subjects with recent (but not acute) LF exposure were more likely to present during the rainy season (May to October) than the dry season (p < 0.001). The findings here suggest that LF remains endemic in Sierra Leone and that caseloads are likely to resume at levels observed prior to the Ebola epidemic. The results provide insight on the current epidemiological profile of LF in Sierra Leone to facilitate LF vaccine studies and accentuate the need for LF cohort studies and continued advancements in LF diagnostics.
RESUMEN
Many countries in sub-Saharan Africa have experienced lower COVID-19 caseloads and fewer deaths than countries in other regions worldwide. Under-reporting of cases and a younger population could partly account for these differences, but pre-existing immunity to coronaviruses is another potential factor. Blood samples from Sierra Leonean Lassa fever and Ebola survivors and their contacts collected before the first reported COVID-19 cases were assessed using enzyme-linked immunosorbent assays for the presence of antibodies binding to proteins of coronaviruses that infect humans. Results were compared to COVID-19 subjects and healthy blood donors from the United States. Prior to the pandemic, Sierra Leoneans had more frequent exposures than Americans to coronaviruses with epitopes that cross-react with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), SARS-CoV, and Middle Eastern respiratory syndrome coronavirus (MERS-CoV). The percentage of Sierra Leoneans with antibodies reacting to seasonal coronaviruses was also higher than for American blood donors. Serological responses to coronaviruses by Sierra Leoneans did not differ by age or sex. Approximately a quarter of Sierra Leonian pre-pandemic blood samples had neutralizing antibodies against SARS-CoV-2 pseudovirus, while about a third neutralized MERS-CoV pseudovirus. Prior exposures to coronaviruses that induce cross-protective immunity may contribute to reduced COVID-19 cases and deaths in Sierra Leone.
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Anticuerpos Antivirales/inmunología , COVID-19/inmunología , Coronavirus del Síndrome Respiratorio de Oriente Medio/inmunología , SARS-CoV-2/inmunología , Distribución por Edad , Alphacoronavirus/inmunología , Anticuerpos Neutralizantes/sangre , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/sangre , Antígenos Virales/inmunología , Betacoronavirus/inmunología , Donantes de Sangre , Proteínas de la Nucleocápside de Coronavirus/inmunología , Protección Cruzada , Reacciones Cruzadas , Epítopos , Femenino , Humanos , Masculino , Fosfoproteínas/inmunología , Sierra Leona , Estados Unidos , Pseudotipado ViralRESUMEN
Lassa virus (LASV) is the causative agent of Lassa fever (LF), an often-fatal hemorrhagic disease. LF is endemic in Nigeria, Sierra Leone and other West African countries. Diagnosis of LASV infection is challenged by the genetic diversity of the virus, which is greatest in Nigeria. The ReLASV Pan-Lassa Antigen Rapid Test (Pan-Lassa RDT) is a point-of-care, in vitro diagnostic test that utilizes a mixture of polyclonal antibodies raised against recombinant nucleoproteins of representative strains from the three most prevalent LASV lineages (II, III and IV). We compared the performance of the Pan-LASV RDT to available quantitative PCR (qPCR) assays during the 2018 LF outbreak in Nigeria. For patients with acute LF (RDT positive, IgG/IgM negative) during initial screening, RDT performance was 83.3% sensitivity and 92.8% specificity when compared to composite results of two qPCR assays. 100% of samples that gave Ct values below 22 on both qPCR assays were positive on the Pan-Lassa RDT. There were significantly elevated case fatality rates and elevated liver transaminase levels in subjects whose samples were RDT positive compared to RDT negative.
Asunto(s)
Anticuerpos Antivirales/metabolismo , Pruebas Diagnósticas de Rutina/métodos , Fiebre de Lassa/diagnóstico , Virus Lassa/aislamiento & purificación , ARN Viral/genética , Adulto , Antígenos Virales/inmunología , Brotes de Enfermedades , Femenino , Humanos , Virus Lassa/genética , Virus Lassa/inmunología , Masculino , Persona de Mediana Edad , Nigeria , Sistemas de Atención de Punto , Sensibilidad y Especificidad , Análisis de Secuencia de ARN , Adulto JovenRESUMEN
Lassa virus (LASV) is the causative agent of Lassa fever, an often-fatal hemorrhagic disease that is endemic in West Africa. Seven genetically distinct LASV lineages have been identified. As part of CEPI's (Coalition for Epidemic Preparedness Innovations) Lassa vaccine development program, we assessed the potential of the human immune system to mount cross-reactive and cross-protective humoral immune responses to antigens from the most prevalent LASV lineages, which are lineages II and III in Nigeria and lineage IV in Sierra Leone. IgG and IgM present in the blood of Lassa fever survivors from Nigeria or Sierra Leone exhibited substantial cross-reactivity for binding to LASV nucleoprotein and two engineered (linked and prefusion) versions of the glycoproteins (GP) of lineages II-IV. There was less cross-reactivity for the Zinc protein. Serum or plasma from Nigerian Lassa fever survivors neutralized LASV pseudoviruses expressing lineage II GP better than they neutralized lineage III or IV GP expressing pseudoviruses. Sierra Leonean survivors did not exhibit a lineage bias. Neutralization titres determined using LASV pseudovirus assays showed significant correlation with titres determined by plaque reduction with infectious LASV. These studies provide guidance for comparison of humoral immunity to LASV of distinct lineages following natural infection or immunization.
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Reacciones Cruzadas/inmunología , Fiebre de Lassa/inmunología , Virus Lassa/inmunología , Anticuerpos/inmunología , Anticuerpos Antivirales/inmunología , Antígenos Virales/inmunología , Variación Genética , Humanos , Inmunidad Humoral , Inmunización , Virus Lassa/patogenicidad , Nigeria/epidemiología , Nucleoproteínas , Proteínas Recombinantes , Sierra Leona/epidemiología , SobrevivientesRESUMEN
Lassa fever, a hemorrhagic fever caused by Lassa virus (LASV), is endemic in West Africa. It is difficult to distinguish febrile illnesses that are common in West Africa from Lassa fever based solely on a patient's clinical presentation. The field performance of recombinant antigen-based Lassa fever immunoassays was compared to that of quantitative polymerase chain assays (qPCRs) using samples from subjects meeting the case definition of Lassa fever presenting to Kenema Government Hospital in Sierra Leone. The recombinant Lassa virus (ReLASV) enzyme-linked immunosorbant assay (ELISA) for detection of viral antigen in blood performed with 95% sensitivity and 97% specificity using a diagnostic standard that combined results of the immunoassays and qPCR. The ReLASV rapid diagnostic test (RDT), a lateral flow immunoassay based on paired monoclonal antibodies to the Josiah strain of LASV (lineage IV), performed with 90% sensitivity and 100% specificity. ReLASV immunoassays performed better than the most robust qPCR currently available, which had 82% sensitivity and 95% specificity. The performance characteristics of recombinant antigen-based Lassa virus immunoassays indicate that they can aid in the diagnosis of LASV Infection and inform the clinical management of Lassa fever patients.
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Anticuerpos Antivirales/inmunología , Antígenos Virales/aislamiento & purificación , Fiebre de Lassa/diagnóstico , Virus Lassa/aislamiento & purificación , África Occidental , Anticuerpos Antivirales/genética , Antígenos Virales/genética , Humanos , Inmunoensayo/métodos , Inmunoglobulina M/inmunología , Fiebre de Lassa/inmunología , Fiebre de Lassa/virología , Virus Lassa/inmunología , Virus Lassa/patogenicidad , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Sierra Leona , Estudios de Validación como AsuntoRESUMEN
The arenavirus Lassa causes severe hemorrhagic fever and a significant disease burden in West Africa every year. The glycoprotein, GPC, is the sole antigen expressed on the viral surface and the critical target for antibody-mediated neutralization. Here we present the crystal structure of the trimeric, prefusion ectodomain of Lassa GP bound to a neutralizing antibody from a human survivor at 3.2-angstrom resolution. The antibody extensively anchors two monomers together at the base of the trimer, and biochemical analysis suggests that it neutralizes by inhibiting conformational changes required for entry. This work illuminates pH-driven conformational changes in both receptor-binding and fusion subunits of Lassa virus, illustrates the unique assembly of the arenavirus glycoprotein spike, and provides a much-needed template for vaccine design against these threats to global health.
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Anticuerpos Neutralizantes/química , Anticuerpos Neutralizantes/metabolismo , Virus Lassa/fisiología , Modelos Moleculares , Proteínas del Envoltorio Viral/química , Proteínas del Envoltorio Viral/metabolismo , Anticuerpos Antivirales/química , Anticuerpos Antivirales/metabolismo , Cristalización , Epítopos/química , Humanos , Concentración de Iones de Hidrógeno , Fiebre de Lassa/inmunología , Fiebre de Lassa/virología , Virus Lassa/química , Virus Lassa/inmunología , Unión Proteica , Conformación Proteica , Multimerización de Proteína , Estabilidad Proteica , Estructura Cuaternaria de Proteína , Internalización del VirusRESUMEN
There are no approved treatments for Lassa fever, which is endemic to the same regions of West Africa that were recently devastated by Ebola. Here we show that a combination of human monoclonal antibodies that cross-react with the glycoproteins of all four clades of Lassa virus is able to rescue 100% of cynomolgus macaques when treatment is initiated at advanced stages of disease, including up to 8 d after challenge.
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Anticuerpos Monoclonales/uso terapéutico , Anticuerpos Neutralizantes/uso terapéutico , Anticuerpos Antivirales/uso terapéutico , Fiebre de Lassa/prevención & control , Animales , Reacciones Cruzadas , Ensayo de Inmunoadsorción Enzimática , Humanos , Evasión Inmune/genética , Inmunohistoquímica , Virus Lassa/genética , Macaca fascicularis , ARN Viral/sangre , Distribución Aleatoria , Tasa de Supervivencia , Carga ViralRESUMEN
Lassa fever is a significant health threat to West African human populations with hundreds of thousands of annual cases. There are no approved medical countermeasures currently available. Compassionate use of the antiviral drug ribavirin or transfusion of convalescent serum has resulted in mixed success depending on when administered or the donor source, respectively. We previously identified several recombinant human monoclonal antibodies targeting the glycoprotein of Lassa virus with strong neutralization profiles in vitro. Here, we demonstrate remarkable therapeutic efficacy using first-in-class human antibodies in a guinea pig model of Lassa infection thereby presenting a promising treatment alternative.
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Anticuerpos Monoclonales/farmacología , Anticuerpos Antivirales/farmacología , Fiebre de Lassa/virología , Virus Lassa/efectos de los fármacos , Animales , Anticuerpos Monoclonales/inmunología , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Cobayas , Humanos , Concentración 50 Inhibidora , Fiebre de Lassa/tratamiento farmacológico , Fiebre de Lassa/inmunología , Virus Lassa/inmunología , Pruebas de NeutralizaciónRESUMEN
Lassa fever is a severe multisystem disease that often has haemorrhagic manifestations. The epitopes of the Lassa virus (LASV) surface glycoproteins recognized by naturally infected human hosts have not been identified or characterized. Here we have cloned 113 human monoclonal antibodies (mAbs) specific for LASV glycoproteins from memory B cells of Lassa fever survivors from West Africa. One-half bind the GP2 fusion subunit, one-fourth recognize the GP1 receptor-binding subunit and the remaining fourth are specific for the assembled glycoprotein complex, requiring both GP1 and GP2 subunits for recognition. Notably, of the 16 mAbs that neutralize LASV, 13 require the assembled glycoprotein complex for binding, while the remaining 3 require GP1 only. Compared with non-neutralizing mAbs, neutralizing mAbs have higher binding affinities and greater divergence from germline progenitors. Some mAbs potently neutralize all four LASV lineages. These insights from LASV human mAb characterization will guide strategies for immunotherapeutic development and vaccine design.