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1.
Nat Struct Mol Biol ; 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31570878

RESUMO

Nipah virus (NiV) and Hendra virus (HeV) are zoonotic henipaviruses (HNVs) responsible for outbreaks of encephalitis and respiratory illness with fatality rates of 50-100%. No vaccines or licensed therapeutics currently exist to protect humans against NiV or HeV. HNVs enter host cells by fusing the viral and cellular membranes via the concerted action of the attachment (G) and fusion (F) glycoproteins, the main targets of the humoral immune response. Here, we describe the isolation and humanization of a potent monoclonal antibody cross-neutralizing NiV and HeV. Cryo-electron microscopy, triggering and fusion studies show the antibody binds to a prefusion-specific quaternary epitope, conserved in NiV F and HeV F glycoproteins, and prevents membrane fusion and viral entry. This work supports the importance of the HNV prefusion F conformation for eliciting a robust immune response and paves the way for using this antibody for prophylaxis and post-exposure therapy with NiV- and HeV-infected individuals.

2.
Cell Rep ; 28(12): 3032-3046.e6, 2019 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-31533029

RESUMO

Zaire ebolavirus (EBOV) VP35 protein is a suppressor of type I interferon (IFN) production, an inhibitor of dendritic cell maturation, and a putative virulence determinant. Here, a recombinant EBOV encoding a mutant VP35 virus (VP35m) is demonstrated to activate RIG-I-like receptor signaling and innate antiviral pathways. When inoculated into cynomolgus macaques, VP35m exhibits dramatic attenuation as compared to wild-type EBOV (wtEBOV), with 20 or 300 times the standard 100% lethal challenge dose not causing EBOV disease (EVD). Further, VP35m infection, despite limited replication in vivo, activates antigen presentation and innate immunity pathways and elicits increased frequencies of proliferating memory T cells and B cells and production of anti-EBOV antibodies. Upon wtEBOV challenge, VP35m-immunized animals survive, exhibiting host responses consistent with an orderly immune response and the absence of excessive inflammation. These data demonstrate that VP35 is a critical EBOV immune evasion factor and provide insights into immune mechanisms of EBOV control.

3.
iScience ; 2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31402258

RESUMO

Here, we show that the US Food and Drug Administration-approved oral drug nitazoxanide (NTZ) broadly amplifies the host innate immune response to viruses and inhibits Ebola virus (EBOV) replication. We find that NTZ enhances retinoic-acid-inducible protein I (RIG-I)-like-receptor, mitochondrial antiviral signaling protein, interferon regulatory factor 3, and interferon activities and induces transcription of the antiviral phosphatase GADD34. NTZ significantly inhibits EBOV replication in human cells through its effects on RIG-I and protein kinase R (PKR), suggesting that it counteracts EBOV VP35 protein's ability to block RIG-I and PKR sensing of EBOV. NTZ also inhibits a second negative-strand RNA virus, vesicular stomatitis virus (VSV), through RIG-I and GADD34, but not PKR, consistent with VSV's distinct host innate immune evasion mechanisms. Thus, NTZ counteracts varied virus-specific immune evasion strategies by generally enhancing the RNA sensing and interferon axis that is triggered by foreign cytoplasmic RNA exposure, and holds promise as an oral therapy against EBOV.

4.
Curr Opin Virol ; 37: 97-104, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31401518

RESUMO

Serum from convalescent Lassa fever patients was previously shown to be ineffective as a source of protective antibodies in some early studies. Subsequently, monoclonal antibodies (MAbs) to the Lassa virus (LASV) glycoprotein produced by memory B cells of West African patients who survived Lassa fever were identified. Development of MAbs as potential Lassa immunotherapeutics was facilitated by structural studies and mutational analyses that identified protective epitopes on the prefusion form of the LASV glycoprotein. Human mAbs were screened for reactivity to different neutralizing epitopes, potency, and broad reactivity against multiple lineages of LASV. MAbs were downselected in a guinea pig model of Lassa fever. A cocktail of three human MAbs designated Arevirumab-3 rescued 100% of Cynomolgus macaques at advanced stages of disease more than a week post-infection. Antibody therapeutics may be further developed in clinical trials in endemic areas potentially offering a key treatment option for Lassa fever.

5.
Sci Rep ; 9(1): 7755, 2019 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-31123310

RESUMO

Crimean-Congo hemorrhagic fever virus (CCHFV), a tick-borne bunyavirus, can cause a life-threatening hemorrhagic syndrome in humans but not in its animal host. The virus is widely distributed throughout southeastern Europe, the Middle East, Africa, and Asia. Disease management has proven difficult and there are no broadly licensed vaccines or therapeutics. Recombinant vesicular stomatitis viruses (rVSV) expressing foreign glycoproteins (GP) have shown promise as experimental vaccines for several viral hemorrhagic fevers. Here, we developed and assessed a replication competent rVSV vector expressing the CCHFV glycoprotein precursor (GPC), which encodes CCHFV structural glycoproteins. This construct drives strong expression of CCHFV-GP, in vitro. Using these vectors, we vaccinated STAT-1 knock-out mice, an animal model for CCHFV. The vector was tolerated and 100% efficacious against challenge from a clinical strain of CCHFV. Anti-CCHFV-GP IgG and neutralizing antibody titers were observed in surviving animals. This study demonstrates that a rVSV expressing only the CCHFV-GP has the potential to serve as a replication competent vaccine platform against CCHF infections.

6.
Emerg Infect Dis ; 25(6): 1144-1152, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31107231

RESUMO

Nipah virus (NiV) is a zoonotic pathogen that causes high case-fatality rates (CFRs) in humans. Two NiV strains have caused outbreaks: the Malaysia strain (NiVM), discovered in 1998-1999 in Malaysia and Singapore (≈40% CFR); and the Bangladesh strain (NiVB), discovered in Bangladesh and India in 2001 (≈80% CFR). Recently, NiVB in African green monkeys resulted in a more severe and lethal disease than NiVM. No NiV vaccines or treatments are licensed for human use. We assessed replication-restricted single-injection recombinant vesicular stomatitis vaccine NiV vaccine vectors expressing the NiV glycoproteins against NiVB challenge in African green monkeys. All vaccinated animals survived to the study endpoint without signs of NiV disease; all showed development of NiV F Ig, NiV G IgG, or both, as well as neutralizing antibody titers. These data show protective efficacy against a stringent and relevant NiVB model of human infection.

7.
Sci Rep ; 9(1): 7329, 2019 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-31065012

RESUMO

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

8.
Cell Host Microbe ; 25(1): 49-58.e5, 2019 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-30629918

RESUMO

Recent and ongoing outbreaks of Ebola virus disease (EVD) underscore the unpredictable nature of ebolavirus reemergence and the urgent need for antiviral treatments. Unfortunately, available experimental vaccines and immunotherapeutics are specific for a single member of the Ebolavirus genus, Ebola virus (EBOV), and ineffective against other ebolaviruses associated with EVD, including Sudan virus (SUDV) and Bundibugyo virus (BDBV). Here we show that MBP134AF, a pan-ebolavirus therapeutic comprising two broadly neutralizing human antibodies (bNAbs), affords unprecedented effectiveness and potency as a therapeutic countermeasure to antigenically diverse ebolaviruses. MBP134AF could fully protect ferrets against lethal EBOV, SUDV, and BDBV infection, and a single 25-mg/kg dose was sufficient to protect NHPs against all three viruses. The development of MBP134AF provides a successful model for the rapid discovery and translational advancement of immunotherapeutics targeting emerging infectious diseases.


Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/uso terapêutico , Anticorpos Antivirais/imunologia , Anticorpos Antivirais/uso terapêutico , Ebolavirus/patogenicidade , Furões/virologia , Doença pelo Vírus Ebola/imunologia , Doença pelo Vírus Ebola/prevenção & controle , Bem-Estar do Animal , Animais , Anticorpos Monoclonais/administração & dosagem , Anticorpos Monoclonais/isolamento & purificação , Anticorpos Neutralizantes/administração & dosagem , Anticorpos Neutralizantes/imunologia , Anticorpos Neutralizantes/isolamento & purificação , Anticorpos Neutralizantes/uso terapêutico , Anticorpos Antivirais/administração & dosagem , Linhagem Celular , Cercopithecus aethiops , Modelos Animais de Doenças , Feminino , Filoviridae/imunologia , Infecções por Filoviridae/imunologia , Infecções por Filoviridae/prevenção & controle , Infecções por Filoviridae/virologia , Glicoproteínas/imunologia , Cobaias , Células HEK293 , Doença pelo Vírus Ebola/virologia , Humanos , Células Matadoras Naturais , Macaca , Macaca fascicularis , Masculino , Primatas , Análise de Sobrevida , Resultado do Tratamento , Proteínas Virais/imunologia
9.
BioDrugs ; 33(1): 9-14, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30604389

RESUMO

Over 40 years since the discovery of Ebola virus, the anti-Ebola virus vaccine efforts of the past 2 decades have culminated in over 12 different vaccine candidates that have been placed into a number of clinical trial phases, past and present. Of these 12 vaccines, four candidates are up to or in phase II clinical trials, and only one has completed the phase III clinical trial stage. While remarkable progress toward a national regulatory agency-approved vaccine for Ebola virus has been made, there remain unanswered questions on issues such as, but not limited to, vaccine protective immunity and duration of that immunity, and the appropriate vaccination strategy for those at risk of Ebola virus infection.


Assuntos
Vacinas contra Ebola/uso terapêutico , Ebolavirus/imunologia , Doença pelo Vírus Ebola/prevenção & controle , Ensaios Clínicos como Assunto , Humanos
10.
J Infect Dis ; 218(suppl_5): S565-S573, 2018 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-29982718

RESUMO

Background: The 2013-2016 Ebola virus disease (EVD) epidemics in West Africa highlighted a need for effective therapeutics for treatment of the disease caused by filoviruses. Monoclonal antibodies (mAbs) are promising therapeutic candidates for prophylaxis or treatment of virus infections. Data about efficacy of human mAb monotherapy against filovirus infections in preclinical nonhuman primate models are limited. Methods: Previously, we described a large panel of human mAbs derived from the circulating memory B cells from Bundibugyo virus (BDBV) infection survivors that bind to the surface glycoprotein (GP) of the virus. We tested one of these neutralizing mAbs that recognized the glycan cap of the GP, designated mAb BDBV289, as monotherapy in rhesus macaques. Results: We found that recombinant mAb BDBV289-N could confer up to 100% protection to BDBV-infected rhesus macaques when treatment was initiated as late as 8 days after virus challenge. Protection was associated with survival and decreased viremia levels in the blood of treated animals. Conclusions: These findings define the efficacy of monotherapy of lethal BDBV infection with a glycan cap-specific mAb and identify a candidate mAb therapeutic molecule that could be included in antibody cocktails for prevention or treatment of ebolavirus infections.

11.
J Infect Dis ; 218(suppl_5): S448-S452, 2018 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-29955887

RESUMO

The domestic ferret was recently described as a uniformly lethal model for 3 species of Ebolavirus. More importantly, this new model utilizes nonadapted wild-type Ebolaviruses. Here, in a proof-of-concept study, we infected ferrets with different variants of the closely related Marburg and Ravn viruses using different doses and routes of exposure. Although ferrets produced a neutralizing humoral response to challenge, we did not observe disease or viremia in any animal. The lack of disease in ferrets underscores the notion that differential mechanisms to immunity among filoviruses exist and may provide a model to better understand how differences contribute to disease.

13.
J Infect Dis ; 218(suppl_5): S582-S587, 2018 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-29939296

RESUMO

A recombinant vesicular stomatitis virus (rVSV) expressing the Marburg virus (MARV) Musoke variant glycoprotein fully protects macaques against 2 MARV variants and Ravn virus as a preventive vaccine and MARV variant Musoke as a postexposure treatment. To evaluate postexposure efficacy against the most pathogenic MARV variant, Angola, we engineered rVSVs expressing homologous Angola glycoprotein. Macaques were challenged with high or low doses of variant Angola and treated 20-30 minutes after exposure. A total of 25% and 60%-75% of treated macaques survived the high-dose and low-dose challenges, respectively. The more rapid disease progression of variant Angola versus variant Musoke may account for the incomplete protection observed.

14.
Nat Rev Drug Discov ; 2018 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-29725132

RESUMO

This corrects the article DOI: 10.1038/nrd.2017.251.

16.
PLoS One ; 13(2): e0192312, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29462200

RESUMO

The search for a universal filovirus vaccine that provides protection against multiple filovirus species has been prompted by sporadic but highly lethal outbreaks of Ebolavirus and Marburgvirus infections. A good prophylactic vaccine should be able to provide protection to all known filovirus species and as an upside potentially protect from newly emerging virus strains. We investigated the immunogenicity and protection elicited by multivalent vaccines expressing glycoproteins (GP) from Ebola virus (EBOV), Sudan virus (SUDV), Taï Forest virus (TAFV) and Marburg virus (MARV). Immune responses against filovirus GP have been associated with protection from disease. The GP antigens were expressed by adenovirus serotypes 26 and 35 (Ad26 and Ad35) and modified Vaccinia virus Ankara (MVA) vectors, all selected for their strong immunogenicity and good safety profile. Using fully lethal NHP intramuscular challenge models, we assessed different vaccination regimens for immunogenicity and protection from filovirus disease. Heterologous multivalent Ad26-Ad35 prime-boost vaccination regimens could give full protection against MARV (range 75%-100% protection) and EBOV (range 50% to 100%) challenge, and partial protection (75%) against SUDV challenge. Heterologous multivalent Ad26-MVA prime-boost immunization gave full protection against EBOV challenge in a small cohort study. The use of such multivalent vaccines did not show overt immune interference in comparison with monovalent vaccines. Multivalent vaccines induced GP-specific antibody responses and cellular IFNγ responses to each GP expressed by the vaccine, and cross-reactivity to TAFV GP was detected in a trivalent vaccine expressing GP from EBOV, SUDV and MARV. In the EBOV challenge studies, higher humoral EBOV GP-specific immune responses (p = 0.0004) were associated with survival from EBOV challenge and less so for cellular immune responses (p = 0.0320). These results demonstrate that it is feasible to generate a multivalent filovirus vaccine that can protect against lethal infection by multiple members of the filovirus family.


Assuntos
Ebolavirus/imunologia , Doença pelo Vírus Ebola/prevenção & controle , Doença do Vírus de Marburg/prevenção & controle , Marburgvirus/imunologia , Vacinas Virais/imunologia , Animais , Feminino , Macaca fascicularis , Masculino
17.
Nat Rev Drug Discov ; 17(6): 413-434, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29375139

RESUMO

The filoviruses - Ebola virus and Marburg virus - cause lethal haemorrhagic fever in humans and non-human primates (NHPs). Filoviruses present a global health threat both as naturally acquired diseases and as potential agents of bioterrorism. In the recent 2013-2016 outbreak of Ebola virus, the most promising therapies for post-exposure use with demonstrated efficacy in the gold-standard NHP models of filovirus disease were unable to show statistically significant protection in patients infected with Ebola virus. This Review briefly discusses these failures and what has been learned from these experiences, and summarizes the current status of post-exposure medical countermeasures in development, including antibodies, small interfering RNA and small molecules. We outline how our current knowledge could be applied to the identification of novel interventions and ways to use interventions more effectively.

18.
J Virol ; 2017 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-29142131

RESUMO

Previous studies demonstrated that a single intramuscular (IM) dose of an attenuated vesicular stomatitis virus vector (Vesiculovax™, rVSV-N4CT1) expressing the glycoprotein (GP) from the Mayinga strain of Zaire ebolavirus (EBOV) protected nonhuman primates (NHP) from lethal challenge with EBOV Kikwit and Makona strains. Here we studied the immunogenicity of an expanded range of attenuated rVSV vectors expressing filovirus GP in mice. Based on data from those studies an optimal attenuated tri-valent rVSV vector formulation was identified which included rVSV vectors expressing EBOV, Sudan ebolavirus (SUDV) or Angola strain of Marburg marburgvirus (MARV) GPs. NHPs were then vaccinated with a single dose of the tri-valent formulation, followed by lethal challenge 28 days later with each of the three corresponding filoviruses. At day 14 post vaccination, a serum IgG response specific for all three GPs was detected in all vaccinated macaques. A modest and balanced cell-mediated immune response specific for each GP protein was also detected in a majority of vaccinated macaques. No matter the level of total GP-specific immune response detected post vaccination, all vaccinated macaques were protected from disease and death following lethal challenge with each of the three filoviruses. These findings indicate that vaccination with a single dose of attenuated rVSV-N4CT1 vectors each expressing a single filovirus GP may provide protection against those filoviruses most commonly responsible for outbreaks of hemorrhagic fever in sub-Saharan Africa.IMPORTANCE The West African Ebola Zaire outbreak in 2013 showed that this disease was not only a regional concern, but a worldwide problem and highlighted the need for a safe and efficacious vaccine to be administered to the populace. However, other endemic pathogens like Ebola Sudan and Marburg also pose an important health risk to the public and therefore require development of a vaccine prior to the occurrence of an outbreak. The significance of our research was the development of a blended tri-valent filovirus vaccine that would elicit a balanced immune response when administered as a single dose and provide complete protection against a lethal challenge of all three filovirus pathogens.

19.
Front Immunol ; 8: 1372, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29123522

RESUMO

Existing models of Ebola virus disease (EVD) suggest antigen-presenting cells are initial targets of Zaire ebolavirus (ZEBOV). In vitro studies have shown that ZEBOV infection of monocytes and macrophages results in the production of inflammatory mediators, which may cause lymphocyte apoptosis. However, these findings have not been corroborated by in vivo studies. In this study, we report the first longitudinal analysis of transcriptional changes in purified monocytes, T-cells, and B-cells isolated from cynomolgus macaques following infection with ZEBOV-Makona. Our data reveal monocytes as one of the major immune cell subsets that supports ZEBOV replication in vivo. In addition, we report a marked increase in the transcription of genes involved in inflammation, coagulation, and vascular disease within monocytes, suggesting that monocytes contribute to EVD manifestations. Further, genes important for antigen presentation and regulation of immunity were downregulated, potentially subverting development of adaptive immunity. In contrast, lymphocytes, which do not support ZEBOV replication, showed transcriptional changes limited to a small number of interferon-stimulated genes (ISGs) and a failure to upregulate genes associated with an antiviral effector immune response. Collectively, these data suggest that ZEBOV-infected monocytes play a significant role in ZEBOV-Makona pathogenesis and strategies to suppress virus replication or modify innate responses to infection in these cells should be a priority for therapeutic intervention.

20.
J Clin Invest ; 127(12): 4437-4448, 2017 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-29106386

RESUMO

Ebolaviruses and marburgviruses belong to the family Filoviridae and cause high lethality in infected patients. There are currently no licensed filovirus vaccines or antiviral therapies. The development of broad-spectrum therapies against members of the Marburgvirus genus, including Marburg virus (MARV) and Ravn virus (RAVV), is difficult because of substantial sequence variability. RNAi therapeutics offer a potential solution, as identification of conserved target nucleotide sequences may confer activity across marburgvirus variants. Here, we assessed the therapeutic efficacy of lipid nanoparticle (LNP) delivery of a single nucleoprotein-targeting (NP-targeting) siRNA in nonhuman primates at advanced stages of MARV or RAVV disease to mimic cases in which patients begin treatment for fulminant disease. Sixteen rhesus monkeys were lethally infected with MARV or RAVV and treated with NP siRNA-LNP, with MARV-infected animals beginning treatment four or five days after infection and RAVV-infected animals starting treatment three or six days after infection. While all untreated animals succumbed to disease, NP siRNA-LNP treatment conferred 100% survival of RAVV-infected macaques, even when treatment began just 1 day prior to the death of the control animals. In MARV-infected animals, day-4 treatment initiation resulted in 100% survival, and day-5 treatment resulted in 50% survival. These results identify a single siRNA therapeutic that provides broad-spectrum protection against both MARV and RAVV.

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