Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
Background: Heterogeneous patterns of malaria transmission are thought to be driven by factors including host genetics, distance to mosquito breeding sites, housing construction, and socio-behavioural characteristics. Evaluation of local transmission epidemiology to characterize malaria risk is essential for planning malaria control and elimination programmes. The use of geographical information systems (GIS) techniques has been a major asset to this approach. To assess time and space distribution of malaria disease in Bandiagara, Mali, within a transmission season, data were used from an ongoing malaria incidence study that enrolled 300 participants aged under six years old ". Methods: Children's households were georeferenced using a handheld global position system. Clinical malaria was defined as a positive blood slide for Plasmodium falciparum asexual stages associated with at least one of the following signs: headache, body aches, fever, chills and weakness. Daily rainfall was measured at the local weather station. Landscape features of Bandiagara were obtained from satellite images and field survey. QGIS™ software was used to map malaria cases, affected and non-affected children, and the number of malaria episodes per child in each block of Bandiagara. Clusters of high or low risk were identified under SaTScan W software according to a Bernoulli model. Results: From June 2009 to May 2010, 296 clinical malaria cases were recorded. Though clearly temporally related to the rains, Plasmodium falciparum occurrence persisted late in the dry season. Two " hot spots " of malaria transmission also found, notably along the Yamé River, characterized by higher than expected numbers of malaria cases, and high numbers of clinical episodes per child. Conversely, the northeastern sector of the town had fewer cases despite its proximity to a large body of standing water which was mosquito habitat. Conclusion: These results confirm the existence of a marked spatial heterogeneity of malaria transmission in Bandiagara, providing support for implementation of targeted interventions. Background Malaria is one of the leading causes of morbidity and mortality in the world, with an estimated 3.3 billion people at risk of malaria [1]. The incidence of malaria worldwide is estimated to be 216 million cases per year, with 81% of these cases occurring in sub-Saharan Africa. Malaria kills approximately 655,000 people per year; 91% of deaths occur in sub-Saharan Africa [1], mostly in children under five years of age. In Mali, West Africa, malaria represents 36.5% of consultation motives in health center, it is a leading cause of morbidity and mortality children of less than five years of age and the first reason of anaemia in pregnant women [2]. Malaria transmission is seasonal. Malaria parasite transmission and clinical disease are characterized by important microgeographic variation, often between adjacent villages, households or families [3-8]. This local heterogeneity is driven by a variety of factors including human genetics [9,10], distance to potential breeding sites [11,12], housing construction
ISSN: 1475-2875

hal-01307672
https://hal-amu.archives-ouvertes.fr/hal-01307672
https://hal-amu.archives-ouvertes.fr/hal-01307672/document
https://hal-amu.archives-ouvertes.fr/hal-01307672/file/1475-2875-12-82.pdf
DOI : 10.1186/1476-072X-2-5

Éditeur(s) : HAL CCSD
Résumé : International audience
The search for safe antimalarial compounds acting against asexual symptom-responsible stages and sexual transmission-responsible forms of Plasmodium species is one of the major challenges in malaria elimination programs. So far, among current drugs approved for human use, only primaquine has transmission-blocking activity. The discovery of small molecules targeting different Plasmodium falcip-arum life stages remains a priority in antimalarial drug research. In this context, several independent studies have recently reported antiplasmodial and transmission-blocking activities of commonly used stains, dyes and fluorescent probes against P. falciparum including chloroquine-resistant isolates. Herein we have studied the antimalarial activities of dyes with different scaffold and we report that the triar-ylmethane dye (TRAM) Brilliant green inhibits the growth of asexual stages (IC 50 2 mM) and has exflagellation-blocking activity (IC 50 800 nM) against P. falciparum reference strains (3D7, 7G8) and chloroquine-resistant clinical isolate (Q206). In a second step we have investigated the antiplasmodial activities of two polysulfonated triarylmethane food dyes. Green S (E142) is weakly active against P. falciparum asexual stage (IC 50 x 17 mM) whereas Patent Blue V (E131) is inactive in both antimalarial assays. By applying liquid chromatography techniques for the culture supernatant analysis after cell washings and lysis, we report the detection of Brilliant green in erythrocytes, the selective uptake of Green S (E142) by infected erythrocytes, whereas Patent Blue V (E131) could not be detected within non-infected and 3D7-infected erythrocytes. Overall, our results suggest that two polysulfonated food dyes might display different affinity with transporters or channels on infected RBC membrane.
International journal for parasitology. Drugs and drug resistance

Droits : http://creativecommons.org/licenses/by-nc-sa/
pasteur-01614675
https://hal-pasteur.archives-ouvertes.fr/pasteur-01614675
https://hal-pasteur.archives-ouvertes.fr/pasteur-01614675/document
https://hal-pasteur.archives-ouvertes.fr/pasteur-01614675/file/Leba%20LJ-article%20colorant-version%20publiee.pdf
DOI : 10.1016/j.ijpddr.2017.07.002

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Sexually transmitted viruses infect the genital and colorectal mucosa of the partner exposed to contaminated genital secretions through a wide range of mechanisms, dictated in part by the organization of the mucosa. Because understanding the modes of entry into the organism of viruses transmitted through sexual intercourse is a necessary prerequisite to the design of treatments to block those infections, in vitro modeling of the transmission is essential. The aim of this review is to present the models and methodologies available for the in vitro study of the interactions between viruses and mucosal tissue and for the preclinical evaluation of antiviral compounds, and to point out their advantages and limitations according to the question being studied.
ISSN: 0042-6822

Droits : http://creativecommons.org/licenses/by/
hal-01663650
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01663650
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01663650/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01663650/file/Frouard%20-%20In%20vitro%20models%20for%20deciphering.pdf
DOI : 10.1016/j.virol.2017.11.023

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
A major requirement for malaria elimination is the development of transmission-blocking interventions. In vitro transmission-blocking bioassays currently mostly rely on the use of very few Plasmodium falciparum reference laboratory strains isolated decades ago. To fill a piece of the gap between laboratory experimental models and natural systems, the purpose of this work was to determine if culture-adapted field isolates of P. falciparum are suitable for in vitro transmission-blocking bioassays targeting functional maturity of male gametocytes: exflagellation. Plasmodium falciparum isolates were adapted to in vitro culture before being used for in vitro gametocyte production. Maturation was assessed by microscopic observation of gametocyte morphology over time of culture and the functional viability of male gametocytes was assessed by microscopic counting of exflagellating gametocytes. Suitability for in vitro exflagellation-blocking bioassays was determined using dihydroartemisinin and methylene blue. In vitro gametocyte production was achieved using two isolates from French Guiana and two isolates from Cambodia. Functional maturity of male gametocytes was assessed by exflagellation observations and all four isolates could be used in exflagellation-blocking bioassays with adequate response to methylene blue and dihydroartemisinin. This work shows that in vitro culture-adapted P. falciparum field isolates of different genetic background, from South America and Southeast Asia, can successfully be used for bioassays targeting the male gametocyte to gamete transition, exflagellation.
ISSN: 1475-2875

Droits : http://creativecommons.org/licenses/by/
pasteur-01182753
https://hal-pasteur.archives-ouvertes.fr/pasteur-01182753
https://hal-pasteur.archives-ouvertes.fr/pasteur-01182753/document
https://hal-pasteur.archives-ouvertes.fr/pasteur-01182753/file/LeBas%20et%202015%20version%20publie%20%281%29.pdf
DOI : 10.1186/s12936-015-0752-x

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : International audience
Adult lymphatic filariae (Wuchereria bancrofti, Brugia malayi) can cause blocking of lymphatics producing obliterating endolymphitis lesions. The subsequent extravasation of lymph (or chyle when the obstruction is canal) is at the origin of the formation of lymphedema or elephantiasis, in which the main histological finding is great hypertrophy of collagen elements. This theory involving filaria only is not the full picture, and bacterial infection, mainly by streptococci, is an important factor. The association of filaria with microbes is particularly dangerous because the presence of the latter, or its toxins, causes death of local microfilariae and even adult worms, which are known to be more harmful dead than alive. The progression of the disease, especially in cases with lymphedema, which mainly affects the limbs and the genital organs, depends on three factors: the species of filaria, the degree of transmission, and the receptivity of the patient to the parasite. Large differences are found according to the region involved, and in the same endemic zone, according to the individuals affected. However, they almost always occur progressively in areas where there have been recurrent attacks of acute lymphangitis.
ISSN: 0398-0499

hal-00715440
https://hal.univ-antilles.fr/hal-00715440
PUBMED : 7007545

Résumé : Les variétés modernes de canne à sucre sont d'origine bispécifique et possèdent une structure génétique complexe, aneuploïde et hautement polyploïde rendant difficile les études de résistance génétique. La feuille jaune de la canne a sucre est une maladie dont l'agent causal est le sugarcane yellow leaf virus (scylv). Ce virus a une large diversité. Seuls trois génotypes viraux, différenciables par rtpcr, ont été trouves en Guadeloupe. Les objectifs de l'étude sont d'évaluer: l/la possibilité de marquer la résistance de la plante au scylv grâce a une étude d'association pan-génomique 2/l'impact de la diversité de l'agent pathogène sur la résistance de la canne a sucre au scylv. Les études d'association ont été menées avec plus de 4000 marqueurs aflp et d'art sur quatre types de données phénotypiques (intensité et densité virale dans les feuilles et les tiges). Les phénotypes ont été mesures sur 189 variétés de cannes à sucre dans deux essais successifs dans un dispositif en trois blocs randomises. De ces variétés, 40 ont été sélectionnées et ont permis d'obtenir 10 croisements biparentaux. Les descendances obtenues ont été suivies sur deux essais. L'incidence et la diversité du scylv ont été évaluées pour les 40 variétés et les descendances. L'héritabilité au sens strict de la résistance aux scylv a été déterminée. Six marqueurs de résistance au scylv ont été identifies ainsi que deux gènes ayant potentiellement un rôle dans la résistance au virus. L'étude montre également que la résistance de la plante est variable en fonction du génotype du scylv et que cette résistance est en partie transmise aux descendances. Créer des variétés résistantes au scylv est donc possible.
Modern varieties of sugarcane have a bispecific origin and a complex genetic structure, aneuploid and highly polyploid, maklng genetic resistance study uneasy to perform. Yellow leaf of sugarcane is a viral disease whose causal agent is the sugarcane yellow leaf virus (scylv). This virus has a wide range of diversity. Only three viral genotypes, distinguishable by rt-pcr, were found in guadeloupe. The objectives of this srudy are to assess: l/the possibility to find markers associated with plant resistance to scylv through a genome wide association study 2 1 the impact of the pathogen diversity on the resistance of sugarcane to scylv. Association studies have been conducted with more than 4000 aflp and dart markers on four types of phenotypic data (virus intensity and density in leaves and canes). Phenotypes were measured on 189 varieties of sugarcane in two successive trials in a three randomized complete block design. From these varieties, 40 were selected and allowed to obtain 10 biparental crosses. The offspring were followed during two trials. The incidence and the diversity of scylv were evaluated in the 40 varieties and the offspring. The narrow sense heritability of the resistance to the scylvs was determined. Six markers of the resistance to the scylv and two genes, with potential contribution in virus resistance, have been identified. The study also shows that the resistance of the plant is variable depending on the scylv genotype and that this resistance is partly transmitted to the offspring. Breeding for scylv resistance is practicable.

http://www.theses.fr/2012AGUY0554/document

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
Resistance to artemisinin casts a shadow on the fight against malaria. The importance of illegal gold miners and of malaria in isolated regions of French Guiana constitutes a threat that endangers the fight against malaria in the Amazon. The hurdles of French laws and the remoteness of the territory from France make it impossible for the system to adapt to the problem of total inaccessibility of an important part of the malaria problem. Transmission is high in these areas and gold miners self-medicate with erratic regimens of artemisinin combinations, thus creating perfect conditions for the emergence of resistance. What needs to be done is being done, but within the limits of national law, with some results. However, facing the same difficult problem, Suriname shows more flexibility and is doing much better than French Guiana despite having lower resources. Local authorities in French Guiana cannot overrule the laws that block appropriate malaria care from reaching a third of malaria-exposed persons. Thus the health authorities in France should take immediate calibrated legislative and financial measures to avoid a predictable disaster.
ISSN: 1475-2875

inserm-00838961
http://www.hal.inserm.fr/inserm-00838961
http://www.hal.inserm.fr/inserm-00838961/document
http://www.hal.inserm.fr/inserm-00838961/file/Nacher_et_al._Malaria_J.pdf
PUBMED : 23641802

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The initiation and subsequent evolution of intra-plate orogens, resulting from continental plate interior deformation due to transmission of stresses over large distances from the active plate boundaries, is controlled by lateral and vertical strength contrasts in the lithosphere. We present lithospheric-scale analogue models combining 1) lateral strength variations in the continental lithosphere, and 2) different vertical rheological stratifications. The experimental continental lithosphere has a four-layer brittle–ductile rheological stratification. Lateral heterogeneity is implemented in all models by increased crustal strength in a central narrow block. The main investigated parameters are strain rate and strength of the lithospheric mantle, both playing an important role in crust–mantle coupling. The experiments show that the presence of a strong crustal domain is effective in localizing deformation along its boundaries. After deformation is localized, the evolution of the orogenic system is governed by the mechanical properties of the lithosphere such that the final geometry of the intra-plate mountain depends on the interplay between crust–mantle coupling and folding versus fracturing of the lithospheric mantle. Underthrusting is the main deformation mode in case of high convergence velocity and/or thick brittle mantle with a final asymmetric architecture of the deep lithosphere. In contrast, lithospheric folding is dominant in case of low convergence velocity and low strength brittle mantle, leading to the development of a symmetric lithospheric root. The presented analogue modelling results provide novel insights for 1) strain localization and 2) the development of the asymmetric architecture of the Pyrenees.
ISSN: 0012-821X

hal-01243577
https://hal.archives-ouvertes.fr/hal-01243577
DOI : 10.1016/j.epsl.2015.05.022