126
|
Markosyan RM, Miao C, Zheng YM, Melikyan GB, Liu SL, Cohen FS. Induction of Cell-Cell Fusion by Ebola Virus Glycoprotein: Low pH Is Not a Trigger. PLoS Pathog 2016; 12:e1005373. [PMID: 26730950 PMCID: PMC4711667 DOI: 10.1371/journal.ppat.1005373] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 12/08/2015] [Indexed: 12/11/2022] Open
Abstract
Ebola virus (EBOV) is a highly pathogenic filovirus that causes hemorrhagic fever in humans and animals. Currently, how EBOV fuses its envelope membrane within an endosomal membrane to cause infection is poorly understood. We successfully measure cell-cell fusion mediated by the EBOV fusion protein, GP, assayed by the transfer of both cytoplasmic and membrane dyes. A small molecule fusion inhibitor, a neutralizing antibody, as well as mutations in EBOV GP known to reduce viral infection, all greatly reduce fusion. By monitoring redistribution of small aqueous dyes between cells and by electrical capacitance measurements, we discovered that EBOV GP-mediated fusion pores do not readily enlarge—a marked difference from the behavior of other viral fusion proteins. EBOV GP must be cleaved by late endosome-resident cathepsins B or L in order to become fusion-competent. Cleavage of cell surface-expressed GP appears to occur in endosomes, as evidenced by the fusion block imposed by cathepsin inhibitors, agents that raise endosomal pH, or an inhibitor of anterograde trafficking. Treating effector cells with a recombinant soluble cathepsin B or thermolysin, which cleaves GP into an active form, increases the extent of fusion, suggesting that a fraction of surface-expressed GP is not cleaved. Whereas the rate of fusion is increased by a brief exposure to acidic pH, fusion does occur at neutral pH. Importantly, the extent of fusion is independent of external pH in experiments in which cathepsin activity is blocked and EBOV GP is cleaved by thermolysin. These results imply that low pH promotes fusion through the well-known pH-dependent activity of cathepsins; fusion induced by cleaved EBOV GP is a process that is fundamentally independent of pH. The cell-cell fusion system has revealed some previously unappreciated features of EBOV entry, which could not be readily elucidated in the context of endosomal entry. The devastation and transmissibility of Ebola virus (EBOV) are well known. However, the manner in which EBOV enters host cells through endosomal membrane remains elusive. Here, we have developed a convenient experimental system to mimic EBOV fusion in endosomes: cells expressing the fusion protein of EBOV, GP, on their surface are fused to target cells. This system exhibits the known key properties of EBOV fusion. We show that the pH-dependence of EBOV fusion is caused by the pH-dependence of cathepsins, proteases known to cleave EBOV GP into a fusion-competent form. We demonstrate that the fusion activity of this cleaved form is independent of pH. We further show that the enlargement of the fusion pore created by EBOV GP is unusually slow in reaching sizes necessary to pass EBOV’s genome—this is atypical of virally created fusion pores. This cell-cell fusion system should provide a useful platform for developing drugs against EBOV infection.
Collapse
|
127
|
Abstract
A historic review of the discovery of new viruses leads to reminders of traditions that have evolved over 118 years. One such tradition gives credit for the discovery of a virus to the investigator(s) who not only carried out the seminal experiments but also correctly interpreted the findings (within the technological context of the day). Early on, ultrafiltration played a unique role in "proving" that an infectious agent was a virus, as did a failure to find any microscopically visible agent, failure to show replication of the agent in the absence of viable cells, thermolability of the agent, and demonstration of a specific immune response to the agent so as to rule out duplicates and close variants. More difficult was "proving" that the new virus was the etiologic agent of the disease ("proof of causation")-for good reasons this matter has been revisited several times over the years as technologies and perspectives have changed. One tradition is that the discoverers get to name their discovery, their new virus (unless some grievous convention has been broken)-the stability of these virus names has been a way to honor the discoverer(s) over the long term. Several vignettes have been chosen to illustrate several difficulties in holding to the traditions (vignettes chosen include vaccinia and variola viruses, yellow fever virus, and influenza viruses. Crimean-Congo hemorrhagic fever virus, Murray Valley encephalitis virus, human immunodeficiency virus 1, Sin Nombre virus, and Ebola virus). Each suggests lessons for the future. One way to assure that discoveries are forever linked with discoverers would be a permanent archive in one of the universal virus databases that have been constructed for other purposes. However, no current database seems ideal-perhaps members of the global community of virologists will have an ideal solution.
Collapse
|
128
|
Noskov AK, Vishnyakov VA, Andaev EI, Chesnokova MV, Kosilko SA, Balakhonov SV. [PLAGUE IN MANCHURIA (1910-1911) AND EBOLA VIRUS DISEASE IN WEST AFRICA (2014-2015): COMMON PREREQUISITES FOR THE DEVELOPMENT OF EPIDEMICS]. MEDITSINSKAIA PARAZITOLOGIIA I PARAZITARNYE BOLEZNI 2016:33-37. [PMID: 27029143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The paper gives the results of a comparative analysis of the prerequisites for the emergence and spread of epidemics of particularly dangerous infections, by using plague in Manchuria (1910-1911) and Ebola virus disease in West Africa (2014-2015) as examples. Analysis of literature and archival data and online information could reveal a number of common factors and conditions, which substantially contributed to the epidemics. Organization of anti-epidemic (preventive) measures in cases of the threatening epidemic spread, of particularly dangerous diseases must be based on the minimization, of the influence of the specific factors and conditions, which facilitate disease transmission in a given area in a given time.
Collapse
|
129
|
Reynard O, Nguyen XN, Alazard-Dany N, Barateau V, Cimarelli A, Volchkov VE. Identification of a New Ribonucleoside Inhibitor of Ebola Virus Replication. Viruses 2015; 7:6233-40. [PMID: 26633464 PMCID: PMC4690858 DOI: 10.3390/v7122934] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 11/16/2015] [Accepted: 11/16/2015] [Indexed: 11/17/2022] Open
Abstract
The current outbreak of Ebola virus (EBOV) in West Africa has claimed the lives of more than 15,000 people and highlights an urgent need for therapeutics capable of preventing virus replication. In this study we screened known nucleoside analogues for their ability to interfere with EBOV replication. Among them, the cytidine analogue β-d-N4-hydroxycytidine (NHC) demonstrated potent inhibitory activities against EBOV replication and spread at non-cytotoxic concentrations. Thus, NHC constitutes an interesting candidate for the development of a suitable drug treatment against EBOV.
Collapse
|
130
|
Wang LL, Chen Q, Zhou LN, Guo Y. [Study of gonadal hormone drugs in blocking filovirus entry of cells in vitro]. YAO XUE XUE BAO = ACTA PHARMACEUTICA SINICA 2015; 50:1545-1550. [PMID: 27169275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This study was designed to discover filovirus entry inhibitors in a drug library of commercial medicines. One thousand and six hundred drugs were screened using the ZEBOV-GP/HIV model, a pseudovirus formed by an HIV-core packed with the Zaire Ebola virus glycoprotein. We identified 12 gonadal hormone drugs with inhibitory activities in ZEBOV-GP/HIV entry at final concentration of 10 μmol x L(-1). Among them, three drugs exhibited strong activities with IC50 < 1 μmol x L(-1), such as toremifene citrate (IC50: 0.19 ± 0.02 μmol x L(-1)), tamoxifen citrate (IC50: 0.32 ± 0.01 μmol x L(-1)) and clomiphene citrate (IC50: 0.53 ± 0.02 μmol x L(-1)); seven drugs had moderate activities with IC50 between 1 and 10 μmol x L(-1), such as estradiol benzoate (IC50: 1.83 ± 5.69 μmol x L(-1)), raloxifene hydrochloride (IC50: 3.48 ± 0.07 μmol x L(-1)), equilin (IC50: 4.00 ± 9.94 μmol x L(-1)), estradiol (IC50: 5.26 ± 9.92 μmol x L(-1)), quinestrol (IC50: 6.36?5.37 gmol-L1), estrone (IC50: 6.87 ± 0.03 μmol-L1) and finasteride (IC50: 9.94 ± 0.45 μmol x L(-1)); two drugs, hexestrol (IC50: 14.20 ± 0.55 μmol x L(-1)) and chlormadinone acetate (IC50: 24.60 ± 0.36 μmol x L(-1)), had weak activities against ZEBOV. Further, toremifene citrate, tamoxifen citrate, clomiphene citrate, raloxifene hydrochloride and quinestrol could block both pseudovirus type Sudan ebola virus (SEBOV-GP/HIV) and Marburg virus (MARV-GP/HIV) entries.
Collapse
|
131
|
Faye O, Andronico A, Faye O, Salje H, Boëlle PY, Magassouba N, Bah EI, Koivogui L, Diallo B, Diallo AA, Keita S, Konde MK, Fowler R, Fall G, Cauchemez S, Sall AA. Use of Viremia to Evaluate the Baseline Case Fatality Ratio of Ebola Virus Disease and Inform Treatment Studies: A Retrospective Cohort Study. PLoS Med 2015; 12:e1001908. [PMID: 26625118 PMCID: PMC4666644 DOI: 10.1371/journal.pmed.1001908] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 10/19/2015] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The case fatality ratio (CFR) of Ebola virus disease (EVD) can vary over time and space for reasons that are not fully understood. This makes it difficult to define the baseline CFRs needed to evaluate treatments in the absence of randomized controls. Here, we investigate whether viremia in EVD patients may be used to evaluate baseline EVD CFRs. METHODS AND FINDINGS We analyzed the laboratory and epidemiological records of patients with EVD confirmed by reverse transcription PCR hospitalized in the Conakry area, Guinea, between 1 March 2014 and 28 February 2015. We used viremia and other variables to model the CFR. Data for 699 EVD patients were analyzed. In the week following symptom onset, mean viremia remained stable, and the CFR increased with viremia, V, from 21% (95% CI 16%-27%) for low viremia (V < 104.4 copies/ml) to 53% (95% CI 44%-61%) for intermediate viremia (104.4 ≤ V < 105.2 copies/ml) and 81% (95% CI 75%-87%) for high viremia (V ≥ 105.2 copies/ml). Compared to adults (15-44 y old [y.o.]), the CFR was larger in young children (0-4 y.o.) (odds ratio [OR]: 2.44; 95% CI 1.02-5.86) and older adults (≥ 45 y.o.) (OR: 2.84; 95% CI 1.81-4.46) but lower in children (5-14 y.o.) (OR: 0.46; 95% CI 0.24-0.86). An order of magnitude increase in mean viremia in cases after July 2014 compared to those before coincided with a 14% increase in the CFR. Our findings come from a large hospital-based study in Conakry and may not be generalizable to settings with different case profiles, such as with individuals who never sought care. CONCLUSIONS Viremia in EVD patients was a strong predictor of death that partly explained variations in CFR in the study population. This study provides baseline CFRs by viremia group, which allow appropriate adjustment when estimating efficacy in treatment studies. In randomized controlled trials, stratifying analysis on viremia groups could reduce sample size requirements by 25%. We hypothesize that monitoring the viremia of hospitalized patients may inform the ability of surveillance systems to detect EVD patients from the different severity strata.
Collapse
|
132
|
Chen Q, Guo Y. [Establishment of a cell-based filovirus entry inhibitor evaluation system]. YAO XUE XUE BAO = ACTA PHARMACEUTICA SINICA 2015; 50:1538-1544. [PMID: 27169274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Ebola virus, the cause of severe and fatal hemorrahagic fever in humans, belongs to filovirus family. This study was designed to establish a cell-based screening and evaluation system in the pharmacological study of antivirus compounds. Three reporter systems were established with recombinant pseudoviral luciferase of HIV core (pNL4-3.Luc.R(-)E(-)) packed with filovirus glycoprotein (EBOV-Zaire GP/HIV-luc, EBOV-Sudan GP/HIV-luc and Marburg GP/HIV-luc), which are required for virus entry of cells. The level of filovirus entry was determined by the expression of luciferase reporter gene in the infected cells. For screening of filovirus entry inhibitors, the vesicular stomatitis G packed pseudovirions (VSVG/HIV-luc) was used to determine the compound specificity. The results of known filovirus entry inhibitors demonstrated successful establishment of the new model systems, which would be useful in high throughput screening of anti-filovirus drugs in the future.
Collapse
|
133
|
Pinsky BA, Sahoo MK, Sandlund J, Kleman M, Kulkarni M, Grufman P, Nygren M, Kwiatkowski R, Baron EJ, Tenover F, Denison B, Higuchi R, Van Atta R, Beer NR, Carrillo AC, Naraghi-Arani P, Mire CE, Ranadheera C, Grolla A, Lagerqvist N, Persing DH. Analytical Performance Characteristics of the Cepheid GeneXpert Ebola Assay for the Detection of Ebola Virus. PLoS One 2015; 10:e0142216. [PMID: 26562786 PMCID: PMC4643052 DOI: 10.1371/journal.pone.0142216] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 10/19/2015] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The recently developed Xpert® Ebola Assay is a novel nucleic acid amplification test for simplified detection of Ebola virus (EBOV) in whole blood and buccal swab samples. The assay targets sequences in two EBOV genes, lowering the risk for new variants to escape detection in the test. The objective of this report is to present analytical characteristics of the Xpert® Ebola Assay on whole blood samples. METHODS AND FINDINGS This study evaluated the assay's analytical sensitivity, analytical specificity, inclusivity and exclusivity performance in whole blood specimens. EBOV RNA, inactivated EBOV, and infectious EBOV were used as targets. The dynamic range of the assay, the inactivation of virus, and specimen stability were also evaluated. The lower limit of detection (LoD) for the assay using inactivated virus was estimated to be 73 copies/mL (95% CI: 51-97 copies/mL). The LoD for infectious virus was estimated to be 1 plaque-forming unit/mL, and for RNA to be 232 copies/mL (95% CI 163-302 copies/mL). The assay correctly identified five different Ebola viruses, Yambuku-Mayinga, Makona-C07, Yambuku-Ecran, Gabon-Ilembe, and Kikwit-956210, and correctly excluded all non-EBOV isolates tested. The conditions used by Xpert® Ebola for inactivation of infectious virus reduced EBOV titer by ≥6 logs. CONCLUSION In summary, we found the Xpert® Ebola Assay to have high analytical sensitivity and specificity for the detection of EBOV in whole blood. It offers ease of use, fast turnaround time, and remote monitoring. The test has an efficient viral inactivation protocol, fulfills inclusivity and exclusivity criteria, and has specimen stability characteristics consistent with the need for decentralized testing. The simplicity of the assay should enable testing in a wide variety of laboratory settings, including remote laboratories that are not capable of performing highly complex nucleic acid amplification tests, and during outbreaks where time to detection is critical.
Collapse
|
134
|
Olabode AS, Jiang X, Robertson DL, Lovell SC. Ebolavirus is evolving but not changing: No evidence for functional change in EBOV from 1976 to the 2014 outbreak. Virology 2015; 482:202-7. [PMID: 25880111 PMCID: PMC4503884 DOI: 10.1016/j.virol.2015.03.029] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 03/11/2015] [Accepted: 03/15/2015] [Indexed: 01/05/2023]
Abstract
The 2014 epidemic of Ebola virus disease (EVD) has had a devastating impact in West Africa. Sequencing of ebolavirus (EBOV) from infected individuals has revealed extensive genetic variation, leading to speculation that the virus may be adapting to humans, accounting for the scale of the 2014 outbreak. We computationally analyze the variation associated with all EVD outbreaks, and find none of the amino acid replacements lead to identifiable functional changes. These changes have minimal effect on protein structure, being neither stabilizing nor destabilizing, are not found in regions of the proteins associated with known functions and tend to cluster in poorly constrained regions of proteins, specifically intrinsically disordered regions. We find no evidence that the difference between the current and previous outbreaks is due to evolutionary changes associated with transmission to humans. Instead, epidemiological factors are likely to be responsible for the unprecedented spread of EVD.
Collapse
|
135
|
Alfson KJ, Avena LE, Beadles MW, Staples H, Nunneley JW, Ticer A, Dick EJ, Owston MA, Reed C, Patterson JL, Carrion R, Griffiths A. Particle-to-PFU ratio of Ebola virus influences disease course and survival in cynomolgus macaques. J Virol 2015; 89:6773-81. [PMID: 25903348 PMCID: PMC4468478 DOI: 10.1128/jvi.00649-15] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 04/08/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED This study addresses the role of Ebola virus (EBOV) specific infectivity in virulence. Filoviruses are highly lethal, enveloped, single-stranded negative-sense RNA viruses that can cause hemorrhagic fever. No approved vaccines or therapies exist for filovirus infections, and infectious virus must be handled in maximum containment. Efficacy testing of countermeasures, in addition to investigations of pathogenicity and immune response, often requires a well-characterized animal model. For EBOV, an obstacle in performing accurate disease modeling is a poor understanding of what constitutes an infectious dose in animal models. One well-recognized consequence of viral passage in cell culture is a change in specific infectivity, often measured as a particle-to-PFU ratio. Here, we report that serial passages of EBOV in cell culture resulted in a decrease in particle-to-PFU ratio. Notably, this correlated with decreased potency in a lethal cynomolgus macaque (Macaca fascicularis) model of infection; animals were infected with the same viral dose as determined by plaque assay, but animals that received more virus particles exhibited increased disease. This suggests that some particles are unable to form a plaque in a cell culture assay but are able to result in lethal disease in vivo. These results have a significant impact on how future studies are designed to model EBOV disease and test countermeasures. IMPORTANCE Ebola virus (EBOV) can cause severe hemorrhagic disease with a high case-fatality rate, and there are no approved vaccines or therapies. Specific infectivity can be considered the total number of viral particles per PFU, and its impact on disease is poorly understood. In stocks of most mammalian viruses, there are particles that are unable to complete an infectious cycle or unable to cause cell pathology in cultured cells. We asked if these particles cause disease in nonhuman primates by infecting monkeys with equal infectious doses of genetically identical stocks possessing either high or low specific infectivities. Interestingly, some particles that did not yield plaques in cell culture assays were able to result in lethal disease in vivo. Furthermore, the number of PFU needed to induce lethal disease in animals was very low. Our results have a significant impact on how future studies are designed to model EBOV disease and test countermeasures.
Collapse
|
136
|
Alexander KA, Sanderson CE, Marathe M, Lewis BL, Rivers CM, Shaman J, Drake JM, Lofgren E, Dato VM, Eisenberg MC, Eubank S. What factors might have led to the emergence of Ebola in West Africa? PLoS Negl Trop Dis 2015; 9:e0003652. [PMID: 26042592 PMCID: PMC4456362 DOI: 10.1371/journal.pntd.0003652] [Citation(s) in RCA: 169] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
An Ebola outbreak of unprecedented scope emerged in West Africa in December 2013 and presently continues unabated in the countries of Guinea, Sierra Leone, and Liberia. Ebola is not new to Africa, and outbreaks have been confirmed as far back as 1976. The current West African Ebola outbreak is the largest ever recorded and differs dramatically from prior outbreaks in its duration, number of people affected, and geographic extent. The emergence of this deadly disease in West Africa invites many questions, foremost among these: why now, and why in West Africa? Here, we review the sociological, ecological, and environmental drivers that might have influenced the emergence of Ebola in this region of Africa and its spread throughout the region. Containment of the West African Ebola outbreak is the most pressing, immediate need. A comprehensive assessment of the drivers of Ebola emergence and sustained human-to-human transmission is also needed in order to prepare other countries for importation or emergence of this disease. Such assessment includes identification of country-level protocols and interagency policies for outbreak detection and rapid response, increased understanding of cultural and traditional risk factors within and between nations, delivery of culturally embedded public health education, and regional coordination and collaboration, particularly with governments and health ministries throughout Africa. Public health education is also urgently needed in countries outside of Africa in order to ensure that risk is properly understood and public concerns do not escalate unnecessarily. To prevent future outbreaks, coordinated, multiscale, early warning systems should be developed that make full use of these integrated assessments, partner with local communities in high-risk areas, and provide clearly defined response recommendations specific to the needs of each community.
Collapse
|
137
|
Zhu X, Yao C, Wei Y, Kou Z, Hu K. [Recent Advances in Vaccines and Drugs Against the Ebola Virus]. BING DU XUE BAO = CHINESE JOURNAL OF VIROLOGY 2015; 31:287-292. [PMID: 26470536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The Ebola virus belongs to the Filovirus family, which causes Ebola hemorrhagic fever (mortality, 25%-90%). An outbreak of infection by the Ebola virus is sweeping across West Africa, leading to high mortality and worldwide panic. The Ebola virus has caused a serious threat to public health, so intensive scientific studies have been carried out. Several vaccines (e.g., rVSV-ZEBOV, ChAd3-ZEBOV) have been put into clinical trials and antiviral drugs (e.g., TKM-Ebola, ZMAPP) have been administered in the emergency setting to patients infected by the Ebola virus. Here, recent advances in vaccines and drugs against the Ebola virus are reviewed.
Collapse
|
138
|
|
139
|
Leroy ÉM. L’Émergence du virus EBOLA chez l’homme: un long processus pas totalement élucidé. BULLETIN DE L'ACADÉMIE NATIONALE DE MÉDECINE 2015. [PMID: 27509685 PMCID: PMC7095178 DOI: 10.1016/s0001-4079(19)30940-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Le virus Ébola cause régulièrement depuis 1976 des petites épidémies meurtrières généralement maitrisées en quelques mois. Alors que seule l’Afrique Centrale en avait été victime jusqu’alors, une épidémie à virus Ébola d’une ampleur extraordinaire embrase dramatiquement plusieurs pays d’Afrique de l’Ouest depuis le mois de décembre 2013 principalement en raison des défaillances majeures dans la mise en œuvre des mesures visant à empêcher les transmissions interhumaines du virus. Après une période d’incubation d’environ une semaine, la maladie se manifeste par l’apparition soudaine d’une forte fièvre aboutissant in fine à des hémorragies multiples puis à la défaillance généralisée des organes. Plusieurs espèces de chauves-souris seraient les principaux réservoirs du virus Ébola. La contamination de l’homme se produirait soit directement auprès des chauves-souris, largement consommées par les populations locales, soit par l’intermédiaire d’espèces animales sensibles au virus, telles que les chimpanzés et les gorilles. À côté de ce « cycle naturel », l’hypothèse d’un « cycle épidémique » impliquant des espèces animales domestiques vivant dans les villages tels que les chiens ou les porcs, tend désormais à être sérieusement avancée. Ainsi, en fonction des animaux impliqués et de la forme clinique des infections développées, les modalités de la contamination de l’homme peuvent être multiples et sont donc encore largement méconnues. Dans un tel contexte, tous les efforts qui pourront être déployés pour percer le mystère de l’émergence du virus Ébola chez l’homme et clarifier les modalités de la transmission du virus, permettront peut-être de prédire voire d’anticiper l’apparition des épidémies. L’objectif de cette revue est de dresser un état des lieux exhaustif de l’écologie du virus Ébola et de mettre en lumière les évènements qui gouvernent la transmission du virus à l’homme tout en précisant les points encore nombreux qui demeurent non élucidés.
Collapse
|
140
|
Leroy ÉM. [The Emergence of Ebola virus in humans: a long process not yet fully understood]. BULLETIN DE L'ACADEMIE NATIONALE DE MEDECINE 2015; 199:651-69; discussion 669-71. [PMID: 27509685 PMCID: PMC7095178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Indexed: 11/14/2023]
Abstract
Since 1976 Ebola virus regularly has caused small deadly outbreaks in Central Africa, usually controlled in a few months. For the first time, an Ebola epidemic of exceptional magnitude dramatically engulfed several countries in West Africa since December 2013. Major failures of implementing measures to prevent human-to-human transmissions are the main cause of this large-scale Ebola outbreak. After about one-week incubation period, the Ebola virus disease is characterized by a sudden onset of high fever leading to multiple hemorrhages and to widespread organ failure. Several bat species constitute the main reservoirs of Ebola viruses. Human contamination would occur either directly from bats, widely consumed by the local populations, or through animal species susceptible to Ebola infection, such as chimpanzees and gorillas. Alongside this "natural cycle", an "epidemic cycle" involving domestic animals living in villages such as dogs or pigs, is seriously suggested. Thus, according to the diversity of concerned animals and their clinical infectionform, modalities of human contamination can be multiple and are still largely unknown. In this context, all efforts that could be made to unravel the mystery of the Ebola virus emergence in humans and clarify modalities of the virus transmission, would allow for predicting or for anticipating the future occurrence of epidemics. This review aims to provide an exhaustive inventory of the Ebola ecology to highlight events governing the virus transmission to humans that still remain unsolved.
Collapse
|
141
|
Bickler SW, Lizardo RE, De Maio A. The transition from a rural to an urban environment alters expression of the human Ebola virus receptor Neiman-Pick C1: implications for the current epidemic in West Africa. Cell Stress Chaperones 2015; 20:203-6. [PMID: 25477151 PMCID: PMC4326391 DOI: 10.1007/s12192-014-0557-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 11/06/2014] [Accepted: 11/11/2014] [Indexed: 01/06/2023] Open
|
142
|
Hensley LE, Dyall J, Olinger GG, Jahrling PB. Lack of effect of lamivudine on Ebola virus replication. Emerg Infect Dis 2015; 21:550-2. [PMID: 25695153 PMCID: PMC4344292 DOI: 10.3201/eid2103.141862] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
|
143
|
Judson S, Prescott J, Munster V. Understanding ebola virus transmission. Viruses 2015; 7:511-21. [PMID: 25654239 PMCID: PMC4353901 DOI: 10.3390/v7020511] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Revised: 01/21/2015] [Accepted: 01/29/2015] [Indexed: 12/01/2022] Open
Abstract
An unprecedented number of Ebola virus infections among healthcare workers and patients have raised questions about our understanding of Ebola virus transmission. Here, we explore different routes of Ebola virus transmission between people, summarizing the known epidemiological and experimental data. From this data, we expose important gaps in Ebola virus research pertinent to outbreak situations. We further propose experiments and methods of data collection that will enable scientists to fill these voids in our knowledge about the transmission of Ebola virus.
Collapse
|
144
|
Chiappelli F, Bakhordarian A, Thames AD, Du AM, Jan AL, Nahcivan M, Nguyen MT, Sama N, Manfrini E, Piva F, Rocha RM, Maida CA. Ebola: translational science considerations. J Transl Med 2015; 13:11. [PMID: 25592846 PMCID: PMC4320629 DOI: 10.1186/s12967-014-0362-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 12/11/2014] [Indexed: 12/13/2022] Open
Abstract
We are currently in the midst of the most aggressive and fulminating outbreak of Ebola-related disease, commonly referred to as "Ebola", ever recorded. In less than a year, the Ebola virus (EBOV, Zaire ebolavirus species) has infected over 10,000 people, indiscriminately of gender or age, with a fatality rate of about 50%. Whereas at its onset this Ebola outbreak was limited to three countries in West Africa (Guinea, where it was first reported in late March 2014, Liberia, where it has been most rampant in its capital city, Monrovia and other metropolitan cities, and Sierra Leone), cases were later reported in Nigeria, Mali and Senegal, as well as in Western Europe (i.e., Madrid, Spain) and the US (i.e., Dallas, Texas; New York City) by late October 2014. World and US health agencies declared that the current Ebola virus disease (EVD) outbreak has a strong likelihood of growing exponentially across the world before an effective vaccine, treatment or cure can be developed, tested, validated and distributed widely. In the meantime, the spread of the disease may rapidly evolve from an epidemics to a full-blown pandemic. The scientific and healthcare communities actively research and define an emerging kaleidoscope of knowledge about critical translational research parameters, including the virology of EBOV, the molecular biomarkers of the pathological manifestations of EVD, putative central nervous system involvement in EVD, and the cellular immune surveillance to EBOV, patient-centered anthropological and societal parameters of EVD, as well as translational effectiveness about novel putative patient-targeted vaccine and pharmaceutical interventions, which hold strong promise, if not hope, to curb this and future Ebola outbreaks. This work reviews and discusses the principal known facts about EBOV and EVD, and certain among the most interesting ongoing or future avenues of research in the field, including vaccination programs for the wild animal vectors of the virus and the disease from global translational science perspective.
Collapse
|
145
|
Abstract
Ebola virus is an enveloped virus with filamentous structure and causes a severe hemorrhagic fever in human and nonhuman primates. Host cell entry is the first essential step in the viral life cycle, which has been extensively studied as one of the therapeutic targets. A virus factor of cell entry is a surface glycoprotein (GP), which is an only essential viral protein in the step, as well as the unique particle structure. The virus also interacts with a lot of host factors to successfully enter host cells. Ebola virus at first binds to cell surface proteins and internalizes into cells, followed by trafficking through endosomal vesicles to intracellular acidic compartments. There, host proteases process GPs, which can interact with an intracellular receptor. Then, under an appropriate circumstance, viral and endosomal membranes are fused, which is enhanced by major structural changes of GPs, to complete host cell entry. Recently the basic research of Ebola virus infection mechanism has markedly progressed, largely contributed by identification of host factors and detailed structural analyses of GPs. This article highlights the mechanism of Ebola virus host cell entry, including recent findings.
Collapse
|
146
|
McElroy A. Understanding bleeding in ebola virus disease. CLINICAL ADVANCES IN HEMATOLOGY & ONCOLOGY : H&O 2015; 13:29-31. [PMID: 25679971 PMCID: PMC4667727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
|
147
|
De Clercq E. Ebola virus (EBOV) infection: Therapeutic strategies. Biochem Pharmacol 2014; 93:1-10. [PMID: 25481298 PMCID: PMC7110990 DOI: 10.1016/j.bcp.2014.11.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 11/20/2014] [Accepted: 11/20/2014] [Indexed: 11/19/2022]
Abstract
Within less than a year after its epidemic started (in December 2013) in Guinea, Ebola virus (EBOV), a member of the filoviridae, has spread over a number of West-African countries (Guinea, Sierra Leone and Liberia) and gained allures that have been unprecedented except by human immunodeficiency virus (HIV). Although EBOV is highly contagious and transmitted by direct contact with body fluids, it could be counteracted by the adequate chemoprophylactic and -therapeutic interventions: vaccines, antibodies, siRNAs (small interfering RNAs), interferons and chemical substances, i.e. neplanocin A derivatives (i.e. 3-deazaneplanocin A), BCX4430, favipiravir (T-705), endoplasmic reticulum (ER) α-glucosidase inhibitors and a variety of compounds that have been found to inhibit EBOV infection blocking viral entry or by a mode of action that still has to be resolved. Much has to be learned from the mechanism of action of the compounds active against VSV (vesicular stomatitis virus), a virus belonging to the rhabdoviridae, that in its mode of replication could be exemplary for the replication of filoviridae.
Collapse
|
148
|
Garrison AR, Giomarelli BG, Lear-Rooney CM, Saucedo CJ, Yellayi S, Krumpe LRH, Rose M, Paragas J, Bray M, Olinger GG, McMahon JB, Huggins J, O'Keefe BR. The cyanobacterial lectin scytovirin displays potent in vitro and in vivo activity against Zaire Ebola virus. Antiviral Res 2014; 112:1-7. [PMID: 25265598 PMCID: PMC4258435 DOI: 10.1016/j.antiviral.2014.09.012] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 09/18/2014] [Accepted: 09/19/2014] [Indexed: 11/18/2022]
Abstract
The cyanobacterial lectin scytovirin (SVN) binds with high affinity to mannose-rich oligosaccharides on the envelope glycoprotein (GP) of a number of viruses, blocking entry into target cells. In this study, we assessed the ability of SVN to bind to the envelope GP of Zaire Ebola virus (ZEBOV) and inhibit its replication. SVN interacted specifically with the protein's mucin-rich domain. In cell culture, it inhibited ZEBOV replication with a 50% virus-inhibitory concentration (EC50) of 50 nM, and was also active against the Angola strain of the related Marburg virus (MARV), with a similar EC50. Injected subcutaneously in mice, SVN reached a peak plasma level of 100 nm in 45 min, but was cleared within 4h. When ZEBOV-infected mice were given 30 mg/kg/day of SVN by subcutaneous injection every 6h, beginning the day before virus challenge, 9 of 10 animals survived the infection, while all infected, untreated mice died. When treatment was begun one hour or one day after challenge, 70-90% of mice survived. Quantitation of infectious virus and viral RNA in samples of serum, liver and spleen collected on days 2 and 5 postinfection showed a trend toward lower titers in treated than control mice, with a significant decrease in liver titers on day 2. Our findings provide further evidence of the potential of natural lectins as therapeutic agents for viral infections.
Collapse
|
149
|
|
150
|
Griffiths PD. Ebola and ethics. Rev Med Virol 2014; 24:363-4. [PMID: 25318448 DOI: 10.1002/rmv.1812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|