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1.
Lancet Infect Dis ; 2021 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-33484646

RESUMEN

BACKGROUND: Lassa fever is endemic in several west African countries. Case-fatality rates ranging from 21% to 69% have been reported. The pathophysiology of the disease in humans and determinants of mortality remain poorly understood. We aimed to determine host protein biomarkers capable of determining disease outcome. METHODS: In this observational study, we analysed left-over blood samples from patients who tested positive for Lassa fever at Irrua Specialist Teaching Hospital, Nigeria, between January, 2014, and April, 2017. We measured viral load, concentrations of clinical chemistry parameters, and levels of 62 circulating proteins involved in inflammation, immune response, and haemostasis. Patients with a known outcome (survival or death) and at least 200 µL of good-quality diagnostic sample were included in logistic regression modelling to assess the correlation of parameters with Lassa fever outcome. Individuals who gave consent could further be enrolled into a longitudinal analysis to assess the association of parameters with Lassa fever outcome over time. Participants were divided into two datasets for the statistical analysis: a primary dataset (samples taken between Jan 1, 2014, and April 1, 2016), and a secondary dataset (samples taken between April 1, 2016, and April 1, 2017). Biomarkers were ranked by area under the receiver operating characteristic curve (AUC) from highest (most predictive) to lowest (least predictive). FINDINGS: Of 554 patients who tested positive for Lassa fever during the study period, 201 (131 in the primary dataset and 70 in the secondary dataset) were included in the biomarker analysis, of whom 74 (49 in the primary dataset and 25 in the secondary dataset) had died and 127 (82 in the primary dataset and 45 in the secondary dataset) had survived. Cycle threshold values (indicating viral load) and levels of 18 host proteins at the time of admission to hospital were significantly correlated with fatal outcome. The best predictors of outcome in both datasets were plasminogen activator inhibitor-1 (PAI-1; AUC 0·878 in the primary dataset and 0·876 in the secondary dataset), soluble thrombomodulin (TM; 0·839 in the primary dataset and 0·875 in the secondary dataset), and soluble tumour necrosis factor receptor superfamily member 1A (TNF-R1; 0·807 in the primary dataset and 0·851 in the secondary dataset), all of which had higher prediction accuracy than viral load (0·774 in the primary dataset and 0·837 in the secondary dataset). Longitudinal analysis (150 patients, of whom 36 died) showed that of the biomarkers that were predictive at admission, PAI-1 levels consistently decreased to normal levels in survivors but not in those who died. INTERPRETATION: The identification of PAI-1 and soluble TM as markers of fatal Lassa fever at admission, and of PAI-1 as a marker of fatal Lassa fever over time, suggests that dysregulated coagulation and fibrinolysis and endothelial damage have roles in the pathophysiology of Lassa fever, providing a mechanistic explanation for the association of Lassa fever with oedema and bleeding. These novel markers might aid in clinical risk stratification and disease monitoring. FUNDING: German Research Foundation, Leibniz Association, and US National Institutes of Health.

2.
Artículo en Inglés | MEDLINE | ID: mdl-33007476

RESUMEN

OBJECTIVES: Investigation whether in depth characterization of virus variant patterns can be used for epidemiological analysis of the first SARS-CoV-2 infection clusters in Hamburg, Germany. METHODS: Metagenomic RNA- and amplicon-sequencing and subsequent variant calling in 25 respiratory samples from SARS-CoV-2 infected patients involved in the earliest infection clusters in Hamburg. RESULTS: Amplikon sequencing and cluster analyses of these SARS-CoV-2 sequences allowed the identification of the first infection cluster and five non-related infection clusters occurring at the beginning of the viral entry of SARS-CoV-2 in the Hamburg metropolitan region. Viral genomics together with epidemiological analyses revealed that the index patient acquired the infection in Northern Italy and transmitted it to two out of 134 contacts. Single nucleotide polymorphisms clearly distinguished the virus variants of the index and other clusters and allowed to track in which sequences worldwide these mutations were first described. Minor variant analyses identified the transmission of intra-host variants in the index cluster and household clusters. CONCLUSIONS: SARS-CoV-2 variant tracing allows the identification of infection clusters and the follow up of infection chains occurring in the population. Furthermore, the follow up of minor viral variants in infection cluster can provide further resolution on transmission events indistinguishable on consensus sequence level.

3.
J Clin Virol ; 132: 104650, 2020 11.
Artículo en Inglés | MEDLINE | ID: mdl-33011643

RESUMEN

BACKGROUND: The ongoing SARS-CoV-2 pandemic presents a unique challenge to diagnostic laboratories. There are preliminary studies correlating qRT-PCR results from different materials to clinical outcomes, yet, comparability is limited due to the plethora of different assays used for diagnostics. In this study we evaluate clinical performance and linear range for the SARS-CoV-2 IVD (cobas6800/8800 system, a fully automated sample-to-result platform) in different clinically relevant matrix materials outside official specifications. METHODS: Assay performance was assessed in human plasma, BAL/BL and transport medium following chemical inactivation. For analytical evaluation, respective matrix materials were spiked with SARS-CoV-2 RNA in ten-fold dilution series. The efficacy of chemical inactivation by guanidine hydrochloride solution was confirmed in cell culture infectivity experiments. For correlation, a total of 289 predetermined clinical samples including respiratory swabs, plasma and lower respiratory tract specimens were subjected to the SARS-CoV-2 IVD test and results were compared. RESULTS: The SARS-CoV-2 IVD showed excellent linearity over four to six log steps depending on matrix material. Chemical inactivation resulted in a reduction in plaque forming units of at least 3.5 log steps, while having no significant impact on assay performance. Inter-run consistency from three different testing sites demonstrated excellent comparability of RT-PCR results (maximum deviation was 1.53 CT). Clinical evaluation for respiratory swabs showed very good agreement with the comparator assay (Positive agreement 95.7 %, negative agreement 98.9 %). CONCLUSION: The SARS-CoV-2 IVD test for the cobas6800/8800 systems offers excellent linear range and inter-run consistency for quantification of SARS-CoV-2 RNA in different matrices outside official specifications.

4.
J Virol ; 94(21)2020 Oct 14.
Artículo en Inglés | MEDLINE | ID: mdl-32817220

RESUMEN

Lassa fever (LF) is a zoonotic viral hemorrhagic fever caused by Lassa virus (LASV), which is endemic to West African countries. Previous studies have suggested an important role for T-cell-mediated immunopathology in LF pathogenesis, but the mechanisms by which T cells influence disease severity and outcome are not well understood. Here, we present a multiparametric analysis of clinical immunology data collected during the 2017-2018 Lassa fever outbreak in Nigeria. During the acute phase of LF, we observed robust activation of the polyclonal T-cell repertoire, which included LASV-specific and antigenically unrelated T cells. However, severe and fatal LF cases were characterized by poor LASV-specific effector T-cell responses. Severe LF was also characterized by the presence of circulating T cells with homing capacity to inflamed tissues, including the gut mucosa. These findings in LF patients were recapitulated in a mouse model of LASV infection, in which mucosal exposure resulted in remarkably high lethality compared to skin exposure. Taken together, our findings indicate that poor LASV-specific T-cell responses and activation of nonspecific T cells with homing capacity to inflamed tissues are associated with severe LF.IMPORTANCE Lassa fever may cause severe disease in humans, in particular in areas of endemicity like Sierra Leone and Nigeria. Despite its public health importance, the pathophysiology of Lassa fever in humans is poorly understood. Here, we present clinical immunology data obtained in the field during the 2018 Lassa fever outbreak in Nigeria indicating that severe Lassa fever is associated with activation of T cells antigenically unrelated to Lassa virus and poor Lassa virus-specific effector T-cell responses. Mechanistically, we show that these bystander T cells express defined tissue homing signatures that suggest their recruitment to inflamed tissues and a putative role of these T cells in immunopathology. These findings open a window of opportunity to consider T-cell targeting as a potential postexposure therapeutic strategy against severe Lassa fever, a hypothesis that could be tested in relevant animal models, such as nonhuman primates.

5.
NPJ Vaccines ; 5: 71, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32802410

RESUMEN

Lassa mammarenavirus (LASV) is a rodent-borne arenavirus endemic to several West African countries. It is the causative agent of human Lassa fever, an acute viral hemorrhagic fever disease. To date, no therapeutics or vaccines against LASV have obtained regulatory approval. Polyclonal neutralizing antibodies derived from hyperimmunized animals may offer a useful strategy for prophylactic and therapeutic intervention to combat human LASV infections. The LASV envelope surface glycoprotein complex (GP) is the major target for neutralizing antibodies, and it is the main viral antigen used for the design of an LASV vaccine. Here, we assessed the immunogenic potential of mammalian cell-derived virus-like particles (VLPs) expressing GP from the prototypic LASV strain Josiah in a native-like conformation as the sole viral antigen. We demonstrate that an adjuvanted prime-boost immunization regimen with GP-derived VLPs elicited neutralizing antibody responses in rabbits, suggesting that effective antigenic epitopes of GP were displayed. Notably, these antibodies exhibited broad reactivity across five genetic lineages of LASV. VLP-based immunization strategies may represent a powerful approach for generating polyclonal sera containing cross-reactive neutralizing antibodies against LASV.

6.
Emerg Microbes Infect ; 9(1): 1761-1770, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-32723007

RESUMEN

We report two outbreaks of Lassa fever that occurred in Benin in 2014 and 2016 with 20 confirmed cases and 50% (10/20) mortality. Benin was not previously considered to be an endemic country for Lassa fever, resulting in a delay to diagnose the disease and its human transmission. Molecular investigations showed the viral genomes to be similar to that of the Togo strain, which is genetically very different from other known strains and confirms the existence of a new lineage. Endemic circulation of Lassa virus in a new territory and the genetic diversity thus confirm that this virus represents a growing threat for West African people. Given the divergence of the Benin strain from the prototypic Josiah Sierra Leone strain frequently used to generate vaccine candidates, the efficacy of vaccine candidates should also be demonstrated with this strain.

7.
Microbiol Resour Announc ; 9(23)2020 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-32499358

RESUMEN

Here, we describe the complete genome sequence of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strain isolated from an oropharyngeal swab sample from a female patient with COVID-19 who was infected in Hamburg, northern Germany.

8.
Sci Rep ; 10(1): 8724, 2020 05 26.
Artículo en Inglés | MEDLINE | ID: mdl-32457420

RESUMEN

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.

9.
BMJ Open ; 10(4): e036936, 2020 04 16.
Artículo en Inglés | MEDLINE | ID: mdl-32303517

RESUMEN

INTRODUCTION: Lassa fever (LF) is a severe and often fatal systemic disease in humans and affects a large number of countries in West Africa. Treatment options are limited to supportive care and the broad-spectrum antiviral agent ribavirin. However, evidence for ribavirin efficacy in patients with LF is poor and pharmacokinetic (PK) data are not available.Irrua Specialist Teaching Hospital (ISTH) developed an intravenous ribavirin regimen different to the WHO recommendation. Apart from a lower total daily dose the drug is usually administered once per day which reduces the exposure of personnel to patients with LF. The aim of this study is to characterise the PK of the Irrua ribavirin regimen. METHODS AND ANALYSIS: This prospective, observational clinical study will assess PK properties of the Irrua ribavirin regimen on routinely ribavirin-treated patients with LF at ISTH, a referral hospital serving 19 local governmental areas in a LF endemic zone in Nigeria. Participants will be adults with PCR-confirmed LF. The primary objective is to describe classical PK parameters for ribavirin (maximum plasma drug concentration, time to maximum plasma drug concentration, area under the plasma drug concentration vs time curve, half-life time T1/2, volume of distribution). Blood samples will be collected at 0.5, 1, 3, 5, 8, 12 and 24 hours after doses on day 1, day 4 and day 10 of ribavirin treatment. Ribavirin plasma concentrations will be determined using liquid chromatography coupled to tandem mass spectrometry. ETHICS AND DISSEMINATION: The study will be conducted in compliance with the protocol, the Declaration of Helsinki, Good Clinical Practice (GCP) and the Nigerian National Code for Health Research Ethics. The protocol has received approval by the Health Research Ethics Committee of ISTH. Results will be made available to LF survivors, their caregivers, the funders, LF research society and other researchers. REGISTRATION DETAILS: ISRCTN11104750.

10.
CPT Pharmacometrics Syst Pharmacol ; 9(5): 258-271, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32198838

RESUMEN

In 2014, our research network was involved in the evaluation of favipiravir, an anti-influenza polymerase inhibitor, against Ebola virus. In this review, we discuss how mathematical modeling was used, first to propose a relevant dosing regimen in humans, and then to optimize its antiviral efficacy in a nonhuman primate (NHP) model. The data collected in NHPs were finally used to develop a model of Ebola pathogenesis integrating the interactions among the virus, the innate and adaptive immune response, and the action of favipiravir. We conclude the review of this work by discussing how these results are of relevance for future human studies in the context of Ebola virus, but also for other emerging viral diseases for which no therapeutics are available.

11.
Antiviral Res ; 175: 104706, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-31931103

RESUMEN

Rocaglates, a class of natural compounds isolated from plants of the genus Aglaia, are potent inhibitors of translation initiation. They are proposed to form stacking interactions with polypurine sequences in the 5'-untranslated region (UTR) of selected mRNAs, thereby clamping the RNA substrate onto eIF4A and causing inhibition of the translation initiation complex. Since virus replication relies on the host translation machinery, it is not surprising that the rocaglate Silvestrol has broad-spectrum antiviral activity. Unfortunately, synthesis of Silvestrol is sophisticated and time-consuming, thus hampering the prospects for further antiviral drug development. Here, we present the less complex structured synthetic rocaglate CR-31-B (-) as a novel compound with potent broad-spectrum antiviral activity in primary cells and in an ex vivo bronchial epithelial cell system. CR-31-B (-) inhibited the replication of corona-, Zika-, Lassa-, Crimean Congo hemorrhagic fever viruses and, to a lesser extent, hepatitis E virus (HEV) at non-cytotoxic low nanomolar concentrations. Since HEV has a polypurine-free 5'-UTR that folds into a stable hairpin structure, we hypothesized that RNA clamping by Silvestrol and its derivatives may also occur in a polypurine-independent but structure-dependent manner. Interestingly, the HEV 5'-UTR conferred sensitivity towards Silvestrol but not to CR-31-B (-). However, if an exposed polypurine stretch was introduced into the HEV 5'-UTR, CR-31-B (-) became an active inhibitor comparable to Silvestrol. Moreover, thermodynamic destabilization of the HEV 5'-UTR led to reduced translational inhibition by Silvestrol, suggesting differences between rocaglates in their mode of action, most probably by engaging Silvestrol's additional dioxane moiety.

12.
J Virol ; 93(21)2019 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-31413134

RESUMEN

Lassa virus is genetically diverse with several lineages circulating in West Africa. This study aimed at describing the sequence variability of Lassa virus across Nigeria and inferring its spatiotemporal evolution. We sequenced and isolated 77 Lassa virus strains from 16 Nigerian states. The final data set, including previous works, comprised metadata and sequences of 219 unique strains sampled between 1969 and 2018 in 22 states. Most of this data originated from Lassa fever patients diagnosed at Irrua Specialist Teaching Hospital, Edo State, Nigeria. The majority of sequences clustered with the main Nigerian lineages II and III, while a few sequences formed a new cluster related to Lassa virus strains from Hylomyscus pamfi Within lineages II and III, seven and five sublineages, respectively, were distinguishable. Phylogeographic analysis suggests an origin of lineage II in the southeastern part of the country around Ebonyi State and a main vector of dispersal toward the west across the Niger River, through Anambra, Kogi, Delta, and Edo into Ondo State. The frontline of virus dispersal appears to be in Ondo. Minor vectors are directed northeast toward Taraba and Adamawa and south toward Imo and Rivers. Lineage III might have spread from northern Plateau State into Kaduna, Nasarawa, Federal Capital Territory, and Bauchi. One sublineage moved south and crossed the Benue River into Benue State. This study provides a geographic mapping of lineages and phylogenetic clusters in Nigeria at a higher resolution. In addition, we estimated the direction and time frame of virus dispersal in the country.IMPORTANCE Lassa virus is the causative agent of Lassa fever, a viral hemorrhagic fever with a case fatality rate of approximately 30% in Africa. Previous studies disclosed a geographical pattern in the distribution of Lassa virus strains and a westward movement of the virus across West Africa during evolution. Our study provides a deeper understanding of the geography of genetic lineages and sublineages of the virus in Nigeria. In addition, we modeled how the virus spread in the country. This knowledge allows us to predict into which geographical areas the virus might spread in the future and prioritize areas for Lassa fever surveillance. Our study not only aimed to generate Lassa virus sequences from across Nigeria but also to isolate and conserve the respective viruses for future research. Both isolates and sequences are important for the development and evaluation of medical countermeasures to treat and prevent Lassa fever, such as diagnostics, therapeutics, and vaccines.


Asunto(s)
Fiebre de Lassa/virología , Virus Lassa/clasificación , Animales , Evolución Molecular , Variación Genética , Humanos , Fiebre de Lassa/epidemiología , Fiebre de Lassa/transmisión , Virus Lassa/genética , Murinae/virología , Nigeria/epidemiología , Filogenia , Filogeografía
13.
J Infect Dis ; 218(suppl_5): S496-S503, 2018 11 22.
Artículo en Inglés | MEDLINE | ID: mdl-30101349

RESUMEN

Background: The pathophysiology of Ebola virus disease (EVD) is still poorly understood. This study aimed at identifying soluble biomarkers that inform on disease mechanisms. Methods: Fifty-four soluble mediators of the immune, coagulation, and endothelial system were measured in baseline and follow-up samples from hospitalized patients with EVD, using Luminex technology. Cross-sectional expression levels and changes over time were correlated with outcome. Results: Levels of circulating proinflammatory cytokines and chemokines, as well as markers of endothelial dysfunction and coagulopathy, were elevated on admission to hospital in patients who died from EVD as compared to survivors. These markers further increased in patients who died and/or decreased over time in survivors. In contrast, markers of gut integrity and T-cell response were higher in survivors and increased until discharge. Conclusions: Inflammatory response, endothelial integrity, gastric tissue protection, and T cell immunity play a role in EVD pathophysiology.


Asunto(s)
Fiebre Hemorrágica Ebola/inmunología , Adulto , Biomarcadores/análisis , Quimiocinas/sangre , Estudios Transversales , Citocinas/sangre , Endotelio Vascular/fisiopatología , Femenino , Fiebre Hemorrágica Ebola/mortalidad , Fiebre Hemorrágica Ebola/fisiopatología , Humanos , Cinética , Masculino , Persona de Mediana Edad , Sobrevivientes , Linfocitos T/inmunología
14.
J Infect Dis ; 218(suppl_5): S508-S518, 2018 11 22.
Artículo en Inglés | MEDLINE | ID: mdl-29986035

RESUMEN

Differences in T-cell phenotype, particularly the expression of markers of T-cell homeostasis, have been observed in fatal and nonfatal Ebola virus disease (EVD). However, the relationship between these markers with T-cell function and virus clearance during EVD is poorly understood. To gain biological insight into the role of T cells during EVD, combined transcriptomics and T-cell receptor sequencing was used to profile blood samples from fatal and nonfatal EVD patients from the recent West African EVD epidemic. Fatal EVD was characterized by strong T-cell activation and increased abundance of T-cell inhibitory molecules. However, the early T-cell response was oligoclonal and did not result in viral clearance. In contrast, survivors mounted highly diverse T-cell responses, maintained low levels of T-cell inhibitors, and cleared Ebola virus. Our findings highlight the importance of T-cell immunity in surviving EVD and strengthen the foundation for further research on targeting of the dendritic cell-T cell interface for postexposure immunotherapy.


Asunto(s)
Fiebre Hemorrágica Ebola/inmunología , Homeostasis , Receptores de Antígenos de Linfocitos T/fisiología , Linfocitos T/inmunología , Biomarcadores , Estudios Transversales , Fiebre Hemorrágica Ebola/genética , Fiebre Hemorrágica Ebola/mortalidad , Humanos , Transcriptoma
15.
mSphere ; 3(3)2018.
Artículo en Inglés | MEDLINE | ID: mdl-29720525

RESUMEN

Arenaviruses pose a major public health threat and cause numerous infections in humans each year. Although most viruses belonging to this family do not cause disease in humans, some arenaviruses, such as Lassa virus and Machupo virus, are the etiological agents of lethal hemorrhagic fevers. The absence of a currently licensed vaccine and the highly pathogenic nature of these viruses both make the necessity of developing viable vaccines and therapeutics all the more urgent. Arenaviruses have a single glycoprotein on the surface of virions, the glycoprotein complex (GPC), and this protein can be used as a target for vaccine development. Here, we describe immunization strategies to generate monoclonal antibodies (MAbs) that cross-react between the glycoprotein complexes of both Old World and New World arenaviruses. Several monoclonal antibodies isolated from immunized mice were highly cross-reactive, binding a range of Old World arenavirus glycoproteins, including that of Lassa virus. One such monoclonal antibody, KL-AV-2A1, bound to GPCs of both New World and Old World viruses, including Lassa and Machupo viruses. These cross-reactive antibodies bound to epitopes present on the glycoprotein 2 subunit of the glycoprotein complex, which is relatively conserved among arenaviruses. Monoclonal antibodies binding to these epitopes, however, did not inhibit viral entry as they failed to neutralize a replication-competent vesicular stomatitis virus pseudotyped with the Lassa virus glycoprotein complex in vitro In addition, no protection from virus challenge was observed in in vivo mouse models. Even so, these monoclonal antibodies might still prove to be useful in the development of clinical and diagnostic assays.IMPORTANCE Several viruses in the Arenaviridae family infect humans and cause severe hemorrhagic fevers which lead to high case fatality rates. Due to their pathogenicity and geographic tropisms, these viruses remain very understudied. As a result, an effective vaccine or therapy is urgently needed. Here, we describe efforts to produce cross-reactive monoclonal antibodies that bind to both New and Old World arenaviruses. All of our MAbs seem to be nonneutralizing and nonprotective and target subunit 2 of the glycoprotein. Due to the lack of reagents such as recombinant glycoproteins and antibodies for rapid detection assays, our MAbs could be beneficial as analytic and diagnostic tools.


Asunto(s)
Anticuerpos Antivirales/inmunología , Arenavirus del Nuevo Mundo/inmunología , Arenavirus del Viejo Mundo/inmunología , Reacciones Cruzadas , Glicoproteínas/inmunología , Proteínas Estructurales Virales/inmunología , Animales , Anticuerpos Monoclonales/inmunología , Anticuerpos Antivirales/aislamiento & purificación , Infecciones por Arenaviridae/inmunología , Infecciones por Arenaviridae/prevención & control , Modelos Animales de Enfermedad , Mapeo Epitopo , Epítopos de Linfocito B/inmunología , Ratones
17.
Sci Rep ; 7(1): 11693, 2017 09 15.
Artículo en Inglés | MEDLINE | ID: mdl-28916737

RESUMEN

Ribavirin is a broad spectrum antiviral which inhibits Lassa virus (LASV) replication in vitro but exhibits a minor effect on viremia in vivo. However, ribavirin significantly improves the disease outcome when administered in combination with sub-optimal doses of favipiravir, a strong antiviral drug. The mechanisms explaining these conflicting findings have not been determined, so far. Here, we used an interdisciplinary approach combining mathematical models and experimental data in LASV-infected mice that were treated with ribavirin alone or in combination with the drug favipiravir to explore different putative mechanisms of action for ribavirin. We test four different hypotheses that have been previously suggested for ribavirin's mode of action: (i) acting as a mutagen, thereby limiting the infectivity of new virions; (ii) reducing viremia by impairing viral production; (iii) modulating cell damage, i.e., by reducing inflammation, and (iv) enhancing antiviral immunity. Our analysis indicates that enhancement of antiviral immunity, as well as effects on viral production or transmission are unlikely to be ribavirin's main mechanism mediating its antiviral effectiveness against LASV infection. Instead, the modeled viral kinetics suggest that the main mode of action of ribavirin is to protect infected cells from dying, possibly reducing the inflammatory response.


Asunto(s)
Antivirales/farmacología , Fiebre de Lassa/tratamiento farmacológico , Virus Lassa/efectos de los fármacos , Ribavirina/farmacología , Amidas/administración & dosificación , Amidas/farmacología , Animales , Antivirales/administración & dosificación , Modelos Animales de Enfermedad , Quimioterapia Combinada , Fiebre de Lassa/virología , Ratones Endogámicos C57BL , Modelos Teóricos , Pirazinas/administración & dosificación , Pirazinas/farmacología , Ribavirina/administración & dosificación , Resultado del Tratamiento , Carga Viral
18.
J Virol ; 91(16)2017 08 15.
Artículo en Inglés | MEDLINE | ID: mdl-28592526

RESUMEN

Out of an estimated 31,100 cases since their discovery in 1976, ebolaviruses have caused approximately 13,000 deaths. The vast majority (∼11,000) of these occurred during the 2013-2016 West African epidemic. Three out of five species in the genus are known to cause Ebola Virus Disease in humans. Several monoclonal antibodies against the ebolavirus glycoprotein are currently in development as therapeutics. However, there is still a paucity of monoclonal antibodies that can cross-react between the glycoproteins of different ebolavirus species, and the mechanism of these monoclonal antibody therapeutics is still not understood in detail. Here, we generated a panel of eight murine monoclonal antibodies (MAbs) utilizing a prime-boost vaccination regimen with a Zaire ebolavirus glycoprotein expression plasmid followed by infection with a vesicular stomatitis virus expressing the Zaire ebolavirus glycoprotein. We tested the binding breadth of the resulting monoclonal antibodies using a set of recombinant surface glycoproteins from Reston, Taï Forest, Bundibugyo, Zaire, Sudan, and Marburg viruses and found two antibodies that showed pan-ebolavirus binding. An in vivo Stat2-/- mouse model was utilized to test the ability of these MAbs to protect from infection with a vesicular stomatitis virus expressing the Zaire ebolavirus glycoprotein. Several of our antibodies, including the broadly binding ones, protected mice from mortality despite lacking neutralization capability in vitro, suggesting their protection may be mediated by Fc-FcR interactions. Indeed, three antibodies displayed cellular phagocytosis and/or antibody-dependent cell-mediated cytotoxicity in vitro Our antibodies, specifically the two identified cross-reactive monoclonal antibodies (KL-2E5 and KL-2H7), might add to the understanding of anti-ebolavirus humoral immunity.IMPORTANCE This study describes the generation of a panel of novel anti-ebolavirus glycoprotein monoclonal antibodies, including two antibodies with broad cross-reactivity to all known ebolavirus species. The antibodies were raised using a heterologous DNA-viral vector prime-boost regimen, resulting in a high proportion of cross-reactive antibodies (25%). Similar vaccination regimens have been used successfully to induce broad protection against influenza viruses in humans, and our limited data indicate that this might be a useful strategy for filovirus vaccines as well. Several of our antibodies showed protective efficacy when tested in a novel murine challenge model and may be developed into future therapeutics.


Asunto(s)
Anticuerpos Monoclonales/inmunología , Anticuerpos Antivirales/inmunología , Protección Cruzada , Ebolavirus/inmunología , Fiebre Hemorrágica Ebola/prevención & control , Factores Inmunológicos/inmunología , Proteínas del Envoltorio Viral/inmunología , Animales , Anticuerpos Monoclonales/administración & dosificación , Anticuerpos Antivirales/administración & dosificación , Citotoxicidad Celular Dependiente de Anticuerpos , Modelos Animales de Enfermedad , Factores Inmunológicos/administración & dosificación , Ratones , Resultado del Tratamiento
19.
PLoS Negl Trop Dis ; 11(5): e0005645, 2017 May.
Artículo en Inglés | MEDLINE | ID: mdl-28558022

RESUMEN

BACKGROUND: Human Ebola infection is characterized by a paralysis of the immune system. A signature of αß T cells in fatal Ebola infection has been recently proposed, while the involvement of innate immune cells in the protection/pathogenesis of Ebola infection is unknown. Aim of this study was to analyze γδ T and NK cells in patients from the Ebola outbreak of 2014-2015 occurred in West Africa, and to assess their association with the clinical outcome. METHODOLOGY/PRINCIPAL FINDINGS: Nineteen Ebola-infected patients were enrolled at the time of admission to the Ebola Treatment Centre in Guinea. Patients were divided in two groups on the basis of the clinical outcome. The analysis was performed by using multiparametric flow cytometry established by the European Mobile Laboratory in the field. A low frequency of Vδ2 T-cells was observed during Ebola infection, independently from the clinical outcome. Moreover, Vδ2 T-cells from Ebola patients massively expressed CD95 apoptotic marker, suggesting the involvement of apoptotic mechanisms in Vδ2 T-cell loss. Interestingly, Vδ2 T-cells from survivors expressed an effector phenotype and presented a lower expression of the CTLA-4 exhaustion marker than fatalities, suggesting a role of effector Vδ2 T-cells in the protection. Furthermore, patients with fatal Ebola infection were characterized by a lower NK cell frequency than patients with non fatal infection. In particular, both CD56bright and CD56dim NK frequency were very low both in fatal and non fatal infections, while a higher frequency of CD56neg NK cells was associated to non-fatal infections. Finally, NK activation and expression of NKp46 and CD158a were independent from clinical outcome. CONCLUSIONS/SIGNIFICANCES: Altogether, the data suggest that both effector Vδ2 T-cells and NK cells may play a role in the complex network of protective response to EBOV infection. Further studies are required to characterize the protective effector functions of Vδ2 and NK cells.


Asunto(s)
Fiebre Hemorrágica Ebola/inmunología , Fiebre Hemorrágica Ebola/mortalidad , Células Asesinas Naturales/inmunología , Receptores de Antígenos de Linfocitos T gamma-delta/inmunología , Subgrupos de Linfocitos T/inmunología , Biomarcadores/metabolismo , Antígeno CD56/metabolismo , Antígeno CTLA-4/metabolismo , Bases de Datos Factuales , Ebolavirus , Femenino , Citometría de Flujo , Guinea/epidemiología , Humanos , Activación de Linfocitos/inmunología , Masculino , Receptor 1 Gatillante de la Citotoxidad Natural/metabolismo , Receptores KIR2DL1/metabolismo , Carga Viral , Receptor fas/metabolismo
20.
Sci Rep ; 7: 43776, 2017 03 03.
Artículo en Inglés | MEDLINE | ID: mdl-28256637

RESUMEN

Ebola virus (EBOV) causes severe systemic disease in humans and non-human primates characterized by high levels of viremia and virus titers in peripheral organs. The natural portals of virus entry are the mucosal surfaces and the skin where macrophages and dendritic cells (DCs) are primary EBOV targets. Due to the migratory properties of DCs, EBOV infection of these cells has been proposed as a necessary step for virus dissemination via draining lymph nodes and blood. Here we utilize chimeric mice with competent hematopoietic-driven immunity, to show that EBOV primarily infects CD11b+ DCs in non-lymphoid and lymphoid tissues, but spares the main cross-presenting CD103+ DC subset. Furthermore, depletion of CD8 and CD4 T cells resulted in loss of early control of virus replication, viremia and fatal Ebola virus disease (EVD). Thus, our findings point out at T cell function as a key determinant of EVD progress and outcome.


Asunto(s)
Ebolavirus/inmunología , Fiebre Hemorrágica Ebola/inmunología , Linfocitos T/inmunología , Replicación Viral/inmunología , Animales , Antígenos CD/inmunología , Antígenos CD/metabolismo , Antígeno CD11b/inmunología , Antígeno CD11b/metabolismo , Reactividad Cruzada/inmunología , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Células Dendríticas/virología , Ebolavirus/fisiología , Fiebre Hemorrágica Ebola/virología , Interacciones Huésped-Patógeno/inmunología , Cadenas alfa de Integrinas/inmunología , Cadenas alfa de Integrinas/metabolismo , Cinética , Tejido Linfoide/inmunología , Tejido Linfoide/metabolismo , Tejido Linfoide/virología , Ratones Endogámicos C57BL , Ratones Noqueados , Viremia/inmunología , Viremia/virología
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