RESUMEN
The 2013-2015 West African epidemic of Ebola virus disease (EVD) reminds us of how little is known about biosafety level 4 viruses. Like Ebola virus, Lassa virus (LASV) can cause hemorrhagic fever with high case fatality rates. We generated a genomic catalog of almost 200 LASV sequences from clinical and rodent reservoir samples. We show that whereas the 2013-2015 EVD epidemic is fueled by human-to-human transmissions, LASV infections mainly result from reservoir-to-human infections. We elucidated the spread of LASV across West Africa and show that this migration was accompanied by changes in LASV genome abundance, fatality rates, codon adaptation, and translational efficiency. By investigating intrahost evolution, we found that mutations accumulate in epitopes of viral surface proteins, suggesting selection for immune escape. This catalog will serve as a foundation for the development of vaccines and diagnostics. VIDEO ABSTRACT.
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Genoma Viral , Fiebre de Lassa/virología , Virus Lassa/genética , ARN Viral/genética , África Occidental/epidemiología , Animales , Evolución Biológica , Reservorios de Enfermedades , Ebolavirus/genética , Variación Genética , Glicoproteínas/genética , Fiebre Hemorrágica Ebola/virología , Humanos , Fiebre de Lassa/epidemiología , Fiebre de Lassa/transmisión , Virus Lassa/clasificación , Virus Lassa/fisiología , Murinae/genética , Mutación , Nigeria/epidemiología , Proteínas Virales/genética , Zoonosis/epidemiología , Zoonosis/virologíaRESUMEN
The 2013-2015 Ebola virus disease (EVD) epidemic is caused by the Makona variant of Ebola virus (EBOV). Early in the epidemic, genome sequencing provided insights into virus evolution and transmission and offered important information for outbreak response. Here, we analyze sequences from 232 patients sampled over 7 months in Sierra Leone, along with 86 previously released genomes from earlier in the epidemic. We confirm sustained human-to-human transmission within Sierra Leone and find no evidence for import or export of EBOV across national borders after its initial introduction. Using high-depth replicate sequencing, we observe both host-to-host transmission and recurrent emergence of intrahost genetic variants. We trace the increasing impact of purifying selection in suppressing the accumulation of nonsynonymous mutations over time. Finally, we note changes in the mucin-like domain of EBOV glycoprotein that merit further investigation. These findings clarify the movement of EBOV within the region and describe viral evolution during prolonged human-to-human transmission.
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Ebolavirus/genética , Ebolavirus/aislamiento & purificación , Genoma Viral , Fiebre Hemorrágica Ebola/epidemiología , Fiebre Hemorrágica Ebola/virología , Mutación , Evolución Biológica , Brotes de Enfermedades , Ebolavirus/clasificación , Fiebre Hemorrágica Ebola/transmisión , Humanos , Sierra Leona/epidemiología , Manejo de EspecímenesRESUMEN
The 2013-2016 West African epidemic caused by the Ebola virus was of unprecedented magnitude, duration and impact. Here we reconstruct the dispersal, proliferation and decline of Ebola virus throughout the region by analysing 1,610 Ebola virus genomes, which represent over 5% of the known cases. We test the association of geography, climate and demography with viral movement among administrative regions, inferring a classic 'gravity' model, with intense dispersal between larger and closer populations. Despite attenuation of international dispersal after border closures, cross-border transmission had already sown the seeds for an international epidemic, rendering these measures ineffective at curbing the epidemic. We address why the epidemic did not spread into neighbouring countries, showing that these countries were susceptible to substantial outbreaks but at lower risk of introductions. Finally, we reveal that this large epidemic was a heterogeneous and spatially dissociated collection of transmission clusters of varying size, duration and connectivity. These insights will help to inform interventions in future epidemics.
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Ebolavirus/genética , Ebolavirus/fisiología , Genoma Viral/genética , Fiebre Hemorrágica Ebola/transmisión , Fiebre Hemorrágica Ebola/virología , Clima , Brotes de Enfermedades/estadística & datos numéricos , Ebolavirus/aislamiento & purificación , Geografía , Fiebre Hemorrágica Ebola/epidemiología , Humanos , Internacionalidad , Modelos Lineales , Epidemiología Molecular , Filogenia , Viaje/legislación & jurisprudencia , Viaje/estadística & datos numéricosRESUMEN
BACKGROUND: Limited clinical and laboratory data are available on patients with Ebola virus disease (EVD). The Kenema Government Hospital in Sierra Leone, which had an existing infrastructure for research regarding viral hemorrhagic fever, has received and cared for patients with EVD since the beginning of the outbreak in Sierra Leone in May 2014. METHODS: We reviewed available epidemiologic, clinical, and laboratory records of patients in whom EVD was diagnosed between May 25 and June 18, 2014. We used quantitative reverse-transcriptase-polymerase-chain-reaction assays to assess the load of Ebola virus (EBOV, Zaire species) in a subgroup of patients. RESULTS: Of 106 patients in whom EVD was diagnosed, 87 had a known outcome, and 44 had detailed clinical information available. The incubation period was estimated to be 6 to 12 days, and the case fatality rate was 74%. Common findings at presentation included fever (in 89% of the patients), headache (in 80%), weakness (in 66%), dizziness (in 60%), diarrhea (in 51%), abdominal pain (in 40%), and vomiting (in 34%). Clinical and laboratory factors at presentation that were associated with a fatal outcome included fever, weakness, dizziness, diarrhea, and elevated levels of blood urea nitrogen, aspartate aminotransferase, and creatinine. Exploratory analyses indicated that patients under the age of 21 years had a lower case fatality rate than those over the age of 45 years (57% vs. 94%, P=0.03), and patients presenting with fewer than 100,000 EBOV copies per milliliter had a lower case fatality rate than those with 10 million EBOV copies per milliliter or more (33% vs. 94%, P=0.003). Bleeding occurred in only 1 patient. CONCLUSIONS: The incubation period and case fatality rate among patients with EVD in Sierra Leone are similar to those observed elsewhere in the 2014 outbreak and in previous outbreaks. Although bleeding was an infrequent finding, diarrhea and other gastrointestinal manifestations were common. (Funded by the National Institutes of Health and others.).
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Ebolavirus/genética , Epidemias , Fiebre Hemorrágica Ebola/epidemiología , Dolor Abdominal , Adulto , Animales , Diarrea , Ebolavirus/aislamiento & purificación , Femenino , Fiebre , Fiebre Hemorrágica Ebola/complicaciones , Fiebre Hemorrágica Ebola/terapia , Fiebre Hemorrágica Ebola/virología , Humanos , Masculino , Persona de Mediana Edad , Mortalidad , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Sierra Leona/epidemiología , Carga Viral , VómitosRESUMEN
BACKGROUND: Kenema Government Hospital (KGH) has developed an advanced clinical and laboratory research capacity to manage the threat of Lassa fever, a viral hemorrhagic fever (VHF). The 2013-2016 Ebola virus (EBOV) disease (EVD) outbreak is the first to have occurred in an area close to a facility with established clinical and laboratory capacity for study of VHFs. METHODS: Because of its proximity to the epicenter of the EVD outbreak, which began in Guinea in March 2014, the KGH Lassa fever Team mobilized to establish EBOV surveillance and diagnostic capabilities. RESULTS: Augustine Goba, director of the KGH Lassa laboratory, diagnosed the first documented case of EVD in Sierra Leone, on 25 May 2014. Thereafter, KGH received and cared for numbers of patients with EVD that quickly overwhelmed the capacity for safe management. Numerous healthcare workers contracted and lost their lives to EVD. The vast majority of subsequent EVD cases in West Africa can be traced back to a single transmission chain that includes this first diagnosed case. CONCLUSIONS: Responding to the challenges of confronting 2 hemorrhagic fever viruses will require continued investments in the development of countermeasures (vaccines, therapeutic agents, and diagnostic assays), infrastructure, and human resources.
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Brotes de Enfermedades , Ebolavirus/aislamiento & purificación , Genoma Viral/genética , Fiebre Hemorrágica Ebola/epidemiología , Fiebre de Lassa/epidemiología , Virus Lassa/aislamiento & purificación , Adolescente , Adulto , África Occidental/epidemiología , Niño , Preescolar , Ebolavirus/genética , Monitoreo Epidemiológico , Femenino , Genómica , Guinea/epidemiología , Fiebre Hemorrágica Ebola/diagnóstico , Fiebre Hemorrágica Ebola/transmisión , Fiebre Hemorrágica Ebola/virología , Humanos , Fiebre de Lassa/diagnóstico , Fiebre de Lassa/transmisión , Fiebre de Lassa/virología , Virus Lassa/genética , Masculino , Persona de Mediana Edad , Análisis de Secuencia de ADN , Sierra Leona/epidemiología , Adulto JovenRESUMEN
BACKGROUND: Ebola virus is the causative agent of a severe syndrome in humans with a fatality rate that can approach 90 %. During infection, the host immune response is thought to become dysregulated, but the mechanisms through which this happens are not entirely understood. In this study, we analyze RNA sequencing data to determine the host response to Ebola virus infection in circulating immune cells. RESULTS: Approximately half of the 100 genes with the strongest early increases in expression were interferon-stimulated genes, such as ISG15, OAS1, IFIT2, HERC5, MX1 and DHX58. Other highly upregulated genes included cytokines CXCL11, CCL7, IL2RA, IL2R1, IL15RA, and CSF2RB, which have not been previously reported to change during Ebola virus infection. Comparing this response in two different models of exposure (intramuscular and aerosol) revealed a similar signature of infection. The strong innate response in the aerosol model was seen not only in circulating cells, but also in primary and secondary target tissues. Conversely, the innate immune response of vaccinated macaques was almost non-existent. This suggests that the innate response is a major aspect of the cellular response to Ebola virus infection in multiple tissues. CONCLUSIONS: Ebola virus causes a severe infection in humans that is associated with high mortality. The host immune response to virus infection is thought to be an important aspect leading to severe pathology, but the components of this overactive response are not well characterized. Here, we analyzed how circulating immune cells respond to the virus and found that there is a strong innate response dependent on active virus replication. This finding is in stark contrast to in vitro evidence showing a suppression of innate immune signaling, and it suggests that the strong innate response we observe in infected animals may be an important contributor to pathogenesis.
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Ebolavirus/fisiología , Fiebre Hemorrágica Ebola/inmunología , Inmunidad Innata , Leucocitos Mononucleares/inmunología , Animales , Ebolavirus/patogenicidad , Perfilación de la Expresión Génica/métodos , Regulación de la Expresión Génica , Redes Reguladoras de Genes , Fiebre Hemorrágica Ebola/genética , Fiebre Hemorrágica Ebola/virología , Leucocitos Mononucleares/metabolismo , Macaca/virología , Ratones , Análisis de Secuencia de ARN/métodos , Replicación ViralRESUMEN
Infection with Lassa virus (LASV) can cause Lassa fever, a haemorrhagic illness with an estimated fatality rate of 29.7%, but causes no or mild symptoms in many individuals. Here, to investigate whether human genetic variation underlies the heterogeneity of LASV infection, we carried out genome-wide association studies (GWAS) as well as seroprevalence surveys, human leukocyte antigen typing and high-throughput variant functional characterization assays. We analysed Lassa fever susceptibility and fatal outcomes in 533 cases of Lassa fever and 1,986 population controls recruited over a 7 year period in Nigeria and Sierra Leone. We detected genome-wide significant variant associations with Lassa fever fatal outcomes near GRM7 and LIF in the Nigerian cohort. We also show that a haplotype bearing signatures of positive selection and overlapping LARGE1, a required LASV entry factor, is associated with decreased risk of Lassa fever in the Nigerian cohort but not in the Sierra Leone cohort. Overall, we identified variants and genes that may impact the risk of severe Lassa fever, demonstrating how GWAS can provide insight into viral pathogenesis.
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Fiebre de Lassa , Humanos , Fiebre de Lassa/genética , Fiebre de Lassa/diagnóstico , Fiebre de Lassa/epidemiología , Estudio de Asociación del Genoma Completo , Estudios Seroepidemiológicos , Virus Lassa/genética , Fiebre , Genética HumanaRESUMEN
We report that Sh3rf2, a homologue of the pro-apoptotic scaffold POSH (Plenty of SH3s), acts as an anti-apoptotic regulator for the c-Jun N-terminal kinase (JNK) pathway. siRNA-mediated knockdown of Sh3rf2 promotes apoptosis of neuronal PC12 cells, cultured cortical neurons, and C6 glioma cells. This death appears to result from activation of JNK signaling. Loss of Sh3rf2 triggers activation of JNK and its target c-Jun. Also, apoptosis promoted by Sh3rf2 knockdown is inhibited by dominant-negative c-Jun as well as by a JNK inhibitor. Investigation of the mechanism by which Sh3rf2 regulates cell survival implicates POSH, a scaffold required for activation of pro-apoptotic JNK/c-Jun signaling. In cells lacking POSH, Sh3rf2 knockdown is unable to activate JNK. We further find that Sh3rf2 binds POSH to reduce its levels by a mechanism that requires the RING domains of both proteins and that appears to involve proteasomal POSH degradation. Conversely, knockdown of Sh3rf2 promotes the stabilization of POSH protein and activation of JNK signaling. Finally, we show that endogenous Sh3rf2 protein rapidly decreases following several different apoptotic stimuli and that knockdown of Sh3rf2 activates the pro-apoptotic JNK pathway in neuronal cells. These findings support a model in which Sh3rf2 promotes proteasomal degradation of pro-apoptotic POSH in healthy cells and in which apoptotic stimuli lead to rapid loss of Sh3rf2 expression, and consequently to stabilization of POSH and JNK activation and cell death. On the basis of these observations, we propose the alternative name POSHER (POSH-eliminating RING protein) for the Sh3rf2 protein.
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Proteínas Adaptadoras Transductoras de Señales/metabolismo , Corteza Cerebral/metabolismo , Modelos Biológicos , Proteínas del Tejido Nervioso/metabolismo , Neuronas/metabolismo , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteolisis , Proteínas Adaptadoras Transductoras de Señales/genética , Animales , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Supervivencia Celular/fisiología , Corteza Cerebral/citología , Activación Enzimática , Técnicas de Silenciamiento del Gen , Células HEK293 , Humanos , Proteínas Quinasas JNK Activadas por Mitógenos/genética , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Proteínas del Tejido Nervioso/genética , Neuronas/citología , Proteínas Oncogénicas/genética , Proteínas Oncogénicas/metabolismo , Células PC12 , Complejo de la Endopetidasa Proteasomal/genética , Proteínas Proto-Oncogénicas c-jun/genética , Proteínas Proto-Oncogénicas c-jun/metabolismo , Ratas , Transducción de Señal/fisiologíaRESUMEN
BACKGROUND: Whole-genome sequencing is an important tool for understanding microbial evolution and identifying the emergence of functionally important variants over the course of epidemics. In October 2010, a severe cholera epidemic began in Haiti, with additional cases identified in the neighboring Dominican Republic. We used whole-genome approaches to sequence four Vibrio cholerae isolates from Haiti and the Dominican Republic and three additional V. cholerae isolates to a high depth of coverage (>2000x); four of the seven isolates were previously sequenced. RESULTS: Using these sequence data, we examined the effect of depth of coverage and sequencing platform on genome assembly and identification of sequence variants. We found that 50x coverage is sufficient to construct a whole-genome assembly and to accurately call most variants from 100 base pair paired-end sequencing reads. Phylogenetic analysis between the newly sequenced and thirty-three previously sequenced V. cholerae isolates indicates that the Haitian and Dominican Republic isolates are closest to strains from South Asia. The Haitian and Dominican Republic isolates form a tight cluster, with only four variants unique to individual isolates. These variants are located in the CTX region, the SXT region, and the core genome. Of the 126 mutations identified that separate the Haiti-Dominican Republic cluster from the V. cholerae reference strain (N16961), 73 are non-synonymous changes, and a number of these changes cluster in specific genes and pathways. CONCLUSIONS: Sequence variant analyses of V. cholerae isolates, including multiple isolates from the Haitian outbreak, identify coverage-specific and technology-specific effects on variant detection, and provide insight into genomic change and functional evolution during an epidemic.
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Cólera/genética , Genoma Bacteriano/genética , Evolución Biológica , Cólera/clasificación , República Dominicana , HaitíRESUMEN
Until recently, Ebola virus (EBOV) was a rarely encountered human pathogen that caused disease among small populations with extraordinarily high lethality. At the end of 2013, EBOV initiated an unprecedented disease outbreak in West Africa that is still ongoing and has already caused thousands of deaths. Recent studies revealed the genomic changes this particular EBOV variant undergoes over time during human-to-human transmission. Here we highlight the genomic changes that might negatively impact the efficacy of currently available EBOV sequence-based candidate therapeutics, such as small interfering RNAs (siRNAs), phosphorodiamidate morpholino oligomers (PMOs), and antibodies. Ten of the observed mutations modify the sequence of the binding sites of monoclonal antibody (MAb) 13F6, MAb 1H3, MAb 6D8, MAb 13C6, and siRNA EK-1, VP24, and VP35 targets and might influence the binding efficacy of the sequence-based therapeutics, suggesting that their efficacy should be reevaluated against the currently circulating strain.
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Ebolavirus/genética , Variación Genética , Fiebre Hemorrágica Ebola/virología , Genómica , Fiebre Hemorrágica Ebola/terapia , Humanos , Mutación , ARN Interferente Pequeño , Proteínas Virales/genética , Proteínas Virales/metabolismoRESUMEN
Next-generation sequencing (NGS) has the potential to transform the discovery of viruses causing unexplained acute febrile illness (UAFI) because it does not depend on culturing the pathogen or a priori knowledge of the pathogen's nucleic acid sequence. More generally, it has the potential to elucidate the complete human virome, including viruses that cause no overt symptoms of disease, but may have unrecognized immunological or developmental consequences. We have used NGS to identify RNA viruses in the blood of 195 patients with UAFI and compared them with those found in 328 apparently healthy (i.e., no overt signs of illness) control individuals, all from communities in southeastern Nigeria. Among UAFI patients, we identified the presence of nucleic acids from several well-characterized pathogenic viruses, such as HIV-1, hepatitis, and Lassa virus. In our cohort of healthy individuals, however, we detected the nucleic acids of two novel rhabdoviruses. These viruses, which we call Ekpoma virus-1 (EKV-1) and Ekpoma virus-2 (EKV-2), are highly divergent, with little identity to each other or other known viruses. The most closely related rhabdoviruses are members of the genus Tibrovirus and Bas-Congo virus (BASV), which was recently identified in an individual with symptoms resembling hemorrhagic fever. Furthermore, by conducting a serosurvey of our study cohort, we find evidence for remarkably high exposure rates to the identified rhabdoviruses. The recent discoveries of novel rhabdoviruses by multiple research groups suggest that human infection with rhabdoviruses might be common. While the prevalence and clinical significance of these viruses are currently unknown, these viruses could have previously unrecognized impacts on human health; further research to understand the immunological and developmental impact of these viruses should be explored. More generally, the identification of similar novel viruses in individuals with and without overt symptoms of disease highlights the need for a broader understanding of the human virome as efforts for viral detection and discovery advance.
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ARN Viral/genética , Infecciones por Rhabdoviridae/diagnóstico , Infecciones por Rhabdoviridae/virología , Rhabdoviridae/aislamiento & purificación , Adulto , África Occidental/epidemiología , Secuencia de Bases , Estudios de Casos y Controles , Femenino , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Masculino , Nigeria/epidemiología , Virus ARN/clasificación , Virus ARN/genética , Virus ARN/aislamiento & purificación , Rhabdoviridae/clasificación , Rhabdoviridae/genética , Infecciones por Rhabdoviridae/epidemiología , Análisis de Secuencia de ARNRESUMEN
Lassa fever (LF) is a severe viral hemorrhagic fever caused by Lassa virus (LASV). The LF program at the Kenema Government Hospital (KGH) in Eastern Sierra Leone currently provides diagnostic services and clinical care for more than 500 suspected LF cases per year. Nearly two-thirds of suspected LF patients presenting to the LF Ward test negative for either LASV antigen or anti-LASV immunoglobulin M (IgM), and therefore are considered to have a non-Lassa febrile illness (NLFI). The NLFI patients in this study were generally severely ill, which accounts for their high case fatality rate of 36%. The current studies were aimed at determining possible causes of severe febrile illnesses in non-LF cases presenting to the KGH, including possible involvement of filoviruses. A seroprevalence survey employing commercial enzyme-linked immunosorbent assay tests revealed significant IgM and IgG reactivity against dengue virus, chikungunya virus, West Nile virus (WNV), Leptospira, and typhus. A polymerase chain reaction-based survey using sera from subjects with acute LF, evidence of prior LASV exposure, or NLFI revealed widespread infection with Plasmodium falciparum malaria in febrile patients. WNV RNA was detected in a subset of patients, and a 419 nt amplicon specific to filoviral L segment RNA was detected at low levels in a single patient. However, 22% of the patients presenting at the KGH between 2011 and 2014 who were included in this survey registered anti-Ebola virus (EBOV) IgG or IgM, suggesting prior exposure to this agent. The 2014 Ebola virus disease (EVD) outbreak is already the deadliest and most widely dispersed outbreak of its kind on record. Serological evidence reported here for possible human exposure to filoviruses in Sierra Leone prior to the current EVD outbreak supports genetic analysis that EBOV may have been present in West Africa for some time prior to the 2014 outbreak.
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Brotes de Enfermedades , Fiebres Hemorrágicas Virales/epidemiología , Fiebres Hemorrágicas Virales/etiología , Anticuerpos Antibacterianos/sangre , Anticuerpos Antivirales/sangre , ADN Protozoario/sangre , Ensayo de Inmunoadsorción Enzimática , Fiebres Hemorrágicas Virales/patología , Humanos , Inmunoglobulina G/sangre , Inmunoglobulina M/sangre , Reacción en Cadena de la Polimerasa , ARN Viral/sangre , Estudios Retrospectivos , Estudios Seroepidemiológicos , Sierra Leona/epidemiologíaRESUMEN
We have developed a robust RNA sequencing method for generating complete de novo assemblies with intra-host variant calls of Lassa and Ebola virus genomes in clinical and biological samples. Our method uses targeted RNase H-based digestion to remove contaminating poly(rA) carrier and ribosomal RNA. This depletion step improves both the quality of data and quantity of informative reads in unbiased total RNA sequencing libraries. We have also developed a hybrid-selection protocol to further enrich the viral content of sequencing libraries. These protocols have enabled rapid deep sequencing of both Lassa and Ebola virus and are broadly applicable to other viral genomics studies.
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Ebolavirus/genética , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Virus Lassa/genética , Fiebre Hemorrágica Ebola/genética , Fiebre Hemorrágica Ebola/virología , Humanos , Fiebre de Lassa/genética , Fiebre de Lassa/virología , ARN ViralRESUMEN
In its largest outbreak, Ebola virus disease is spreading through Guinea, Liberia, Sierra Leone, and Nigeria. We sequenced 99 Ebola virus genomes from 78 patients in Sierra Leone to ~2000× coverage. We observed a rapid accumulation of interhost and intrahost genetic variation, allowing us to characterize patterns of viral transmission over the initial weeks of the epidemic. This West African variant likely diverged from central African lineages around 2004, crossed from Guinea to Sierra Leone in May 2014, and has exhibited sustained human-to-human transmission subsequently, with no evidence of additional zoonotic sources. Because many of the mutations alter protein sequences and other biologically meaningful targets, they should be monitored for impact on diagnostics, vaccines, and therapies critical to outbreak response.
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Brotes de Enfermedades , Ebolavirus/genética , Monitoreo Epidemiológico , Fiebre Hemorrágica Ebola/transmisión , Fiebre Hemorrágica Ebola/virología , Secuencia de Bases , Ebolavirus/aislamiento & purificación , Variación Genética , Genoma Viral/genética , Genómica/métodos , Fiebre Hemorrágica Ebola/epidemiología , Humanos , Mutación , Análisis de Secuencia de ADN , Sierra Leona/epidemiologíaRESUMEN
In 2014, Ebola virus (EBOV) was identified as the etiological agent of a large and still expanding outbreak of Ebola virus disease (EVD) in West Africa and a much more confined EVD outbreak in Middle Africa. Epidemiological and evolutionary analyses confirmed that all cases of both outbreaks are connected to a single introduction each of EBOV into human populations and that both outbreaks are not directly connected. Coding-complete genomic sequence analyses of isolates revealed that the two outbreaks were caused by two novel EBOV variants, and initial clinical observations suggest that neither of them should be considered strains. Here we present consensus decisions on naming for both variants (West Africa: "Makona", Middle Africa: "Lomela") and provide database-compatible full, shortened, and abbreviated names that are in line with recently established filovirus sub-species nomenclatures.
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Ebolavirus/clasificación , Fiebre Hemorrágica Ebola/virología , Terminología como Asunto , República Democrática del Congo/epidemiología , Brotes de Enfermedades , Ebolavirus/genética , Ebolavirus/aislamiento & purificación , Guinea/epidemiología , Fiebre Hemorrágica Ebola/epidemiología , Humanos , Filogenia , ARN Viral/genética , Análisis de Secuencia de ADNRESUMEN
BACKGROUND: Lassa fever (LF), an often-fatal hemorrhagic disease caused by Lassa virus (LASV), is a major public health threat in West Africa. When the violent civil conflict in Sierra Leone (1991 to 2002) ended, an international consortium assisted in restoration of the LF program at Kenema Government Hospital (KGH) in an area with the world's highest incidence of the disease. METHODOLOGY/PRINCIPAL FINDINGS: Clinical and laboratory records of patients presenting to the KGH Lassa Ward in the post-conflict period were organized electronically. Recombinant antigen-based LF immunoassays were used to assess LASV antigenemia and LASV-specific antibodies in patients who met criteria for suspected LF. KGH has been reestablished as a center for LF treatment and research, with over 500 suspected cases now presenting yearly. Higher case fatality rates (CFRs) in LF patients were observed compared to studies conducted prior to the civil conflict. Different criteria for defining LF stages and differences in sensitivity of assays likely account for these differences. The highest incidence of LF in Sierra Leone was observed during the dry season. LF cases were observed in ten of Sierra Leone's thirteen districts, with numerous cases from outside the traditional endemic zone. Deaths in patients presenting with LASV antigenemia were skewed towards individuals less than 29 years of age. Women self-reporting as pregnant were significantly overrepresented among LASV antigenemic patients. The CFR of ribavirin-treated patients presenting early in acute infection was lower than in untreated subjects. CONCLUSIONS/SIGNIFICANCE: Lassa fever remains a major public health threat in Sierra Leone. Outreach activities should expand because LF may be more widespread in Sierra Leone than previously recognized. Enhanced case finding to ensure rapid diagnosis and treatment is imperative to reduce mortality. Even with ribavirin treatment, there was a high rate of fatalities underscoring the need to develop more effective and/or supplemental treatments for LF.
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Fiebre de Lassa/epidemiología , Virus Lassa/aislamiento & purificación , Adolescente , Adulto , Factores de Edad , Anticuerpos Antivirales/sangre , Antígenos Virales/sangre , Niño , Preescolar , Femenino , Humanos , Inmunoensayo , Incidencia , Lactante , Fiebre de Lassa/diagnóstico , Fiebre de Lassa/tratamiento farmacológico , Fiebre de Lassa/mortalidad , Masculino , Embarazo , Complicaciones Infecciosas del Embarazo/epidemiología , Ribavirina/uso terapéutico , Estaciones del Año , Sierra Leona/epidemiología , Análisis de Supervivencia , Adulto JovenRESUMEN
Sequence determination of complete or coding-complete genomes of viruses is becoming common practice for supporting the work of epidemiologists, ecologists, virologists, and taxonomists. Sequencing duration and costs are rapidly decreasing, sequencing hardware is under modification for use by non-experts, and software is constantly being improved to simplify sequence data management and analysis. Thus, analysis of virus disease outbreaks on the molecular level is now feasible, including characterization of the evolution of individual virus populations in single patients over time. The increasing accumulation of sequencing data creates a management problem for the curators of commonly used sequence databases and an entry retrieval problem for end users. Therefore, utilizing the data to their fullest potential will require setting nomenclature and annotation standards for virus isolates and associated genomic sequences. The National Center for Biotechnology Information's (NCBI's) RefSeq is a non-redundant, curated database for reference (or type) nucleotide sequence records that supplies source data to numerous other databases. Building on recently proposed templates for filovirus variant naming [
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Bases de Datos de Ácidos Nucleicos , Filoviridae/genética , Evolución Molecular , Filoviridae/clasificación , Humanos , Selección GenéticaRESUMEN
BACKGROUND: Lassa fever is a viral hemorrhagic fever endemic in West Africa. However, none of the hospitals in the endemic areas of Nigeria has the capacity to perform Lassa virus diagnostics. Case identification and management solely relies on non-specific clinical criteria. The Irrua Specialist Teaching Hospital (ISTH) in the central senatorial district of Edo State struggled with this challenge for many years. METHODOLOGY/PRINCIPAL FINDINGS: A laboratory for molecular diagnosis of Lassa fever, complying with basic standards of diagnostic PCR facilities, was established at ISTH in 2008. During 2009 through 2010, samples of 1,650 suspected cases were processed, of which 198 (12%) tested positive by Lassa virus RT-PCR. No remarkable demographic differences were observed between PCR-positive and negative patients. The case fatality rate for Lassa fever was 31%. Nearly two thirds of confirmed cases attended the emergency departments of ISTH. The time window for therapeutic intervention was extremely short, as 50% of the fatal cases died within 2 days of hospitalization--often before ribavirin treatment could be commenced. Fatal Lassa fever cases were older (p = 0.005), had lower body temperature (p<0.0001), and had higher creatinine (p<0.0001) and blood urea levels (p<0.0001) than survivors. Lassa fever incidence in the hospital followed a seasonal pattern with a peak between November and March. Lassa virus sequences obtained from the patients originating from Edo State formed--within lineage II--a separate clade that could be further subdivided into three clusters. CONCLUSIONS/SIGNIFICANCE: Lassa fever case management was improved at a tertiary health institution in Nigeria through establishment of a laboratory for routine diagnostics of Lassa virus. Data collected in two years of operation demonstrate that Lassa fever is a serious public health problem in Edo State and reveal new insights into the disease in hospitalized patients.
Asunto(s)
Fiebre de Lassa/diagnóstico , Virus Lassa/aislamiento & purificación , Técnicas de Diagnóstico Molecular/métodos , Reacción en Cadena de la Polimerasa/métodos , Adolescente , Adulto , Antivirales/uso terapéutico , Femenino , Hospitales de Enseñanza , Humanos , Fiebre de Lassa/tratamiento farmacológico , Fiebre de Lassa/mortalidad , Virus Lassa/genética , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , Nigeria , ARN Viral/genética , Ribavirina/uso terapéutico , Análisis de Secuencia de ADN , Análisis de Supervivencia , Adulto JovenRESUMEN
Here, we explore the role of Cbl proteins in regulation of neuronal apoptosis. In two paradigms of neuron apoptosis - nerve growth factor (NGF) deprivation and DNA damage - cellular levels of c-Cbl and Cbl-b fell well before the onset of cell death. NGF deprivation also induced rapid loss of tyrosine phosphorylation (and most likely, activation) of c-Cbl. Targeting c-Cbl and Cbl-b with siRNAs to mimic their loss/inactivation sensitized neuronal cells to death promoted by NGF deprivation or DNA damage. One potential mechanism by which Cbl proteins might affect neuronal death is by regulation of apoptotic c-Jun N-terminal kinase (JNK) signaling. We demonstrate that Cbl proteins interact with the JNK pathway components mixed lineage kinase (MLK) 3 and POSH and that knockdown of Cbl proteins is sufficient to increase JNK pathway activity. Furthermore, expression of c-Cbl blocks the ability of MLKs to signal to downstream components of the kinase cascade leading to JNK activation and protects neuronal cells from death induced by MLKs, but not from downstream JNK activators. On the basis of these findings, we propose that Cbls suppress cell death in healthy neurons at least in part by inhibiting the ability of MLKs to activate JNK signaling. Apoptotic stimuli lead to loss of Cbl protein/activity, thereby removing a critical brake on JNK activation and on cell death.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Apoptosis , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Neuronas/enzimología , Proteínas Proto-Oncogénicas c-cbl/metabolismo , Proteínas Adaptadoras Transductoras de Señales/genética , Animales , Línea Celular Tumoral , Daño del ADN , Humanos , Células Jurkat , Quinasas Quinasa Quinasa PAM/metabolismo , Factor de Crecimiento Nervioso/metabolismo , Neuronas/metabolismo , Células PC12 , Fosforilación , Proteínas Proto-Oncogénicas c-cbl/genética , Interferencia de ARN , ARN Interferente Pequeño/metabolismo , Ratas , Transducción de Señal , Proteina Quinasa Quinasa Quinasa 11 Activada por MitógenoRESUMEN
Nix, a pro-apoptotic BH3-only protein, promotes apoptosis of non-neuronal cells, although the mechanisms involved remain incompletely understood. Using a yeast two-hybrid screen with POSH (plenty of SH3 domains, a scaffold involved in activation of the apoptotic JNK/c-Jun pathway) as the bait, we identified an interaction between POSH and Nix. Co-immunoprecipitation and in vitro binding studies confirmed a direct interaction between POSH and Nix in mammalian cells. When overexpressed in HEK293 cells, Nix promotes apoptosis along with enhanced phosphorylation/activation of JNKs and their target c-Jun. These effects appear to be dependent on POSH because Nix does not promote either JNK/c-Jun phosphorylation or apoptosis of 293 cells that do not express POSH. Nix and POSH appear to mutually stabilize one another and this effect could contribute to their promotion of death. Past work showed induction of Nix transcripts in a cellular model of Parkinson disease based on neuronal PC12 cells exposed to 6-hydroxydopamine. Here, we confirm elevation of Nix protein in this model and that Nix over-expression causes apoptotic death of PC12 cells by a mechanism dependent on c-Jun activation. Expression of s-Nix, a dominant-negative form of Nix, protects neuronal PC12 cells from 6-hydroxydopamine but not from nerve growth factor deprivation. These results indicate that Nix promotes cell death via interaction with POSH and activation of the JNK/c-Jun pathway and that Nix protein is induced and contributes to cell death in a cellular model of Parkinson disease.