Detection of Lassa virus, Mali.
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ABSTRACT:
SUBMITTER: Safronetz D
PROVIDER: S-EPMC3321918 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Lassa virus (LASV) is endemic to several nations in West Africa. In Mali, LASV was unknown until an exported case of Lassa fever was reported in 2009. Since that time, rodent surveys have found evidence of LASV-infected Mastomys natalensis rats in several communities in southern Mali, near the border with Côte d'Ivoire. Despite increased awareness, to date only a single case of Lassa fever has been confirmed in Mali. We conducted a survey to determine the prevalence of LASV exposure among persons in 3 villages in southern Mali where the presence of infected rodents has been documented. LASV IgG seroprevalence ranged from 14.5% to 44% per village. No sex bias was noted; however, seropositivity rates increased with participant age. These findings confirm human LASV exposure in Mali and suggest that LASV infection/Lassa fever is a potential public health concern in southern Mali.
| S-EPMC4806955 | biostudies-literature
Project description:Lassa fever is an acute viral illness characterized by multi-organ failure and hemorrhagic manifestations. Lassa fever is most frequently diagnosed in Nigeria, Sierra Leone, Liberia, and Guinea, although sporadic cases have been recorded in other West African countries, including Mali. The etiological agent of Lassa fever is Lassa virus (LASV), an Arenavirus which is maintained in nature and frequently transmitted to humans by Mastomys natalensis. The purpose of this study was to better define the geographic distribution of LASV-infected rodents in sub-Saharan Mali.Small mammals were live-trapped at various locations across Mali for the purpose of identifying potential zoonotic pathogens. Serological and molecular assays were employed and determined LASV infected rodents were exclusively found in the southern Mali near the border of Côte d'Ivoire. Overall, 19.4% of Mastomys natalensis sampled in this region had evidence of LASV infection, with prevalence rates for individual villages ranging from 0 to 52%. Full-length genomic sequences were determined using high throughput sequencing methodologies for LASV isolates generated from tissue samples of rodents collected in four villages and confirmed the phylogenetic clustering of Malian LASV with strain AV.The risk of human infections with LASV is greatest in villages in southern Mali. Lassa fever should be considered in the differential diagnosis for febrile individuals and appropriate diagnostic techniques need to be established to determine the incidence of infection and disease in these regions.
| S-EPMC3855028 | biostudies-literature
Project description:Previous imported cases of Lassa fever (LF) into the United Kingdom from the Ivory Coast and Mali, as well as the detection of Lassa virus (LASV) among the Mastomys natalensis population within Mali has led to the suggestion that the endemic area for LF is expanding. Initial phylogenetic analyses arrange isolates from Mali and the Ivory Coast separately from the classical lineage IV isolates taken from Sierra Leone, Guinea, and Liberia. The availability of full genome sequences continues to increase, allowing for a more complete phylogenetic comparison of the isolates from Mali and the Ivory Coast to the other existing isolates. In this study, we utilized a Bayesian approach to infer the demographic histories of each LASV isolate for which the full sequence was available. Our results indicate that the isolates from Mali and the Ivory Coast group separately from the isolates of lineage IV, comprising a distinct fifth lineage. The split between lineages IV and V is estimated to have occurred around 200-300 years ago, which coincides with the colonial period of West Africa.
| S-EPMC4589679 | biostudies-literature
Project description:We report detection of Lassa virus and Crimean-Congo hemorrhagic fever virus infections in the area of Bamako, the capital of Mali. Our investigation found 2 cases of infection with each of these viruses. These results show the potential for both of these viruses to be endemic to Mali.
| S-EPMC6478234 | biostudies-literature
Project description:Deep mutational scanning of the Lassa virus Josiah strain glycoprotein complex (GPC)
| PRJNA1071644 | ENA
Project description:The virulence of Soromba-R, a Lassa virus strain recently isolated from southern Mali, was assessed in 2 animal models of Lassa fever: inbred strain 13 guinea pigs and cynomolgus macaques. In both models, the Malian isolate demonstrated tissue tropism and viral titers similar to those of historical Lassa virus isolates from Sierra Leone (Josiah) and Liberia (Z-132); however, the Soromba-R isolate was found to be less pathogenic, as determined by decreased mortality and prolonged time to euthanasia in macaques. Interestingly, in addition to the classic indicators of Lassa fever, Soromba-R infection presented with moderate to severe pulmonary manifestations in the macaque model. Analysis of host responses demonstrated increased immune activation in Soromba-R-infected macaques, particularly in neutrophil-activating or -potentiating proinflammatory cytokines or growth factors, including tumor necrosis factor ?, macrophage inflammatory protein 1?, interleukin 1?, and granulocyte colony-stimulating factor, as well as interleukin 5, which may be responsible for the decreased lethality and uncharacteristic clinical presentation. These results suggest that the strain of Lassa virus circulating in Mali might be less pathogenic than strains circulating in the historical region of endemicity and may result in an atypical presentation for Lassa fever, which could complicate clinical diagnosis.
| S-EPMC3603532 | biostudies-literature
Project description:Lassa virus (LASV) is a causative agent of hemorrhagic fever in West Africa. In recent years, it has been imported several times to Europe and North America. The method of choice for early detection of LASV in blood is RT-PCR. Therefore, the European Network for Diagnostics of 'Imported' Viral Diseases (ENIVD) performed an external quality assessment (EQA) study for molecular detection of LASV. A proficiency panel of 13 samples containing various concentrations of inactivated LASV strains Josiah, Lib-1580/121, CSF, or AV was prepared. Samples containing the LASV-related lymphocytic choriomeningitis virus (LCMV) and negative sera were included as specificity controls. Twenty-four laboratories from 17 countries (13 European, one African, one Asian, two American countries) participated in the study. Thirteen laboratories (54%) reported correct results, 4 (17%) laboratories reported 1 to 2 false-negative results, and 7 (29%) laboratories reported 3 to 5 false-negative results. This EQA study indicates that most participating laboratories have a good or acceptable performance in molecular detection of LASV. However, several laboratories need to review and improve their diagnostic procedures.
| S-EPMC4440764 | biostudies-literature
Project description:In this study, a simple one-step reverse transcription-loop-mediated isothermal amplification (RT-LAMP) assay for rapid detection of Lassa virus (LASV) was established. The two primer sets were designed to detect LASV circulating in Sierra Leone and northeastern Nigeria. The RT-LAMP assay using these primer sets was able to detect 100 copies of the in vitro transcribed artificial LASV RNA within 25 min. The assay was also evaluated using intact viral RNA extracted from cell culture-propagated viruses and confirmed to be highly specific for LASV. The RT-LAMP assay developed in this study is rapid, simple, and highly specific for the detection of LASV, although its sensitivity is slightly lower than that of real-time RT-PCR. In addition, because the RT-LAMP assay does not require the use of sophisticated equipment, it would be advantageous for clinical diagnosis of LASV infection in developing countries. It might also be employed in cases of deliberate release during bioterrorism attacks or in epidemiological surveillance for disease outbreaks.
| S-EPMC3406174 | biostudies-literature
Project description:The cell entry and humoral immune response of the human pathogen Lassa virus (LV), a biosafety level 4 (BSL4) Old World arenavirus, are not well characterized. LV pseudoparticles (LVpp) are a surrogate model system that has been used to decipher factors and routes involved in LV cell entry under BSL2 conditions. Here, we describe LVpp, which are highly infectious, with titers approaching those obtained with pseudoparticles displaying G protein of vesicular stomatitis virus and their the use for the characterization of LV cell entry and neutralization. Upon cell attachment, LVpp utilize endocytic vesicles for cell entry as described for many pH-dependent viruses. However, the fusion of the LV glycoproteins is activated at unusually low pH values, with optimal fusion occurring between pH 4.5 and 3, a pH range at which fusion characteristics of viral glycoproteins have so far remained largely unexplored. Consistent with a shifted pH optimum for fusion activation, we found wild-type LV and LVpp to display a remarkable resistance to exposure to low pH. Finally, LVpp allow the fast and quantifiable detection of neutralizing antibodies in human and animal sera and will thus facilitate the study of the humoral immune response in LV infections.
| S-EPMC2655582 | biostudies-literature
Project description:We describe the isolation and characterization of a new Lassa virus strain imported into Germany by a traveler who had visited Ghana, Côte D'Ivoire, and Burkina Faso. This strain, designated "AV," originated from a region in West Africa where Lassa fever has not been reported. Viral S RNA isolated from the patient's serum was amplified and sequenced. A long-range reverse transcription polymerase chain reaction allowed amplification of the full-length (3.4 kb) S RNA. The coding sequences of strain AV differed from those of all known Lassa prototype strains (Josiah, Nigeria, and LP) by approximately 20%, mainly at third codon positions. Phylogenetically, strain AV appears to be most closely related to strain Josiah from Sierra Leone. Lassa viruses comprise a group of genetically highly diverse strains, which has implications for vaccine development. The new method for full-length S RNA amplification may facilitate identification and molecular analysis of new arenaviruses or arenavirus strains.
| S-EPMC2627947 | biostudies-other