CNRS Host-Pathogen-Environment Interactions Laboratory

Perpignan, France

CNRS Host-Pathogen-Environment Interactions Laboratory

Perpignan, France
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Ayata S.D.,University Pierre and Marie Curie | Ayata S.D.,French National Center for Scientific Research | Huret M.,Center Ifremer Of Nantes | Irisson J.O.,CNRS Host-Pathogen-Environment Interactions Laboratory
Progress in Oceanography | Year: 2010

Climate may act on the dispersal and connectivity of marine populations through changes in the oceanic circulation and temperature, and by modifying species' prey and predator distributions. As dispersal and connectivity remain difficult to assess in situ, a first step in studying the effects of climate change can be achieved using biophysical models. To date, only a few biophysical models have been used for this purpose. Here we review these studies and also include results from other recent modelling efforts. We show that increased sea temperature, a major change expected under climate warming, may impact dispersal and connectivity patterns via changes in reproductive phenology (e.g., shift in the spawning season), transport (e.g., reduced pelagic larval duration under faster development rates), mortality (e.g., changes in the exposure to lethal temperatures), and behaviour (e.g., increased larval swimming speed). Projected changes in circulation are also shown to have large effects on the simulated dispersal and connectivity patterns. Although these biophysical modelling studies are useful preliminary approaches to project the potential effects of climate change, we highlight their current limitations and discuss the way forward, in particular the need for adequate coupled hydrodynamic-biogeochemical simulations using atmospheric forcing from realistic climate change scenarios. © 2010 Elsevier Ltd.

Vignon M.,CNRS Host-Pathogen-Environment Interactions Laboratory | Vignon M.,French National Institute for Agricultural Research
Zoologica Scripta | Year: 2011

Taxonomists and evolutionary biologists frequently use a combination of morphological measurements to distinguish between species and investigate local adaptation. However, the entire set of characters often displays various degrees of collinearity. This paper discusses the effect of using collinear data in morphological taxonomy and ways to handle multicollinearity in a classification context, with special consideration for small sample size. In addition, I propose a robust and easy-to-use combination of dimension reduction using partial least squares (PLS) with traditional discriminant methods for morphological data. To do this, I investigated morphological variation patterns among four monogenean populations from the Pacific Ocean using the correlated morphological features of the sclerotized attachment organ. The new approach yielded better prediction results (lower classification error rates) than the traditional dimension reduction method based on principle component analysis (PCA) and is also much more robust for small sample size. This emphasizes that PLS may be more efficient than PCA in dealing with correlated data and extracting the most relevant morphological differences among groups. © 2011 The Author. Zoologica Scripta © 2011 The Norwegian Academy of Science and Letters.

Thetiot-Laurent S.A.-L.,CNRS Coordination Chemistry | Boissier J.,University of Perpignan | Boissier J.,CNRS Host-Pathogen-Environment Interactions Laboratory | Robert A.,CNRS Coordination Chemistry | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2013

After malaria, schistosomiasis (or bilharzia) is the second most prevalent disease in Africa, and is occurring in over 70 countries in tropical and subtropical regions. It is estimated that 600 million people are at risk of infection, 200 million people are infected, and at least 200 000 deaths per year are associated with the disease. All schistosome species are transmitted through contact with fresh water that is infested with free-swimming forms of the parasite, which is known as cercariae and produced by snails. When located in the blood vessels of the host, larval and adult schistosomes digest red cells to acquire amino acids for growth and development. Vaccine candidates have been unsuccessful up to now. Against such devastating parasitic disease, the antischistosomal arsenal is currently limited to a single drug, praziquantel, which has been used for more than 35 years. Because the question of the reduction of the activity of praziquantel was raised recently, it is thus urgent to create new and safe antischistosomal drugs that should be combined with praziquantel to develop efficient bitherapies. Bilharziasis (schistosomiasis) is the second most prevalent parasitic disease in Africa after malaria. The therapeutic arsenal against this disease is currently limited to a single drug, praziquantel, which has been used for 35 years. It is thus urgent to develop new antischistosomal drugs for efficient bi- or tri-therapies in combination with praziquantel. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tang L.H.,CNRS Host-Pathogen-Environment Interactions Laboratory | Lim J.H.,CNRS Host-Pathogen-Environment Interactions Laboratory | Kuah L.F.,CNRS Host-Pathogen-Environment Interactions Laboratory | Lau Y.F.,National University of Singapore
Vaccine | Year: 2014

A prototype H7 influenza vaccine constructed based on the H7N7 outbreak in 2003 was tested for the protective efficacy against the novel H7N9 virus in a lethal murine challenge model. Serum samples from vaccinated mice showed significant neutralizing activity against the H7N9 virus and the mice were completely protected with no significant weight loss. The results have direct implications on how to overcome potential vaccine shortage and identify donors for immune sera for passive immunization. © 2014 Elsevier Ltd. All rights reserved.

Giraud T.,University Paris - Sud | Gourbiere S.,University of Sussex | Gourbiere S.,CNRS Host-Pathogen-Environment Interactions Laboratory | Gourbiere S.,French National Center for Scientific Research
Heredity | Year: 2012

Reproductive isolation is an essential ingredient of speciation, and much has been learned in recent years about the evolution of reproductive isolation and the genetics of reproductive barriers in animals and plants. Fungi have been neglected on these aspects, despite being tractable model eukaryotes. Here, we used a model fitting approach to look at the importance of different barriers to gene flow to explain the decrease of reproductive compatibility with genetic distance in fungi. We found support for the occurrence of reinforcement in the presyngamy compatibility among basidiomycetes. In contrast, no evidence for reinforcement was detected in ascomycetes, concurring with the idea that host/habitat adaptation in this group can pleiotropically cause reproductive isolation. We found no evidence of a snowballing accumulation of postsyngamic reproductive incompatibilities in either ascomycetes or the complex of anther smut fungi. Together with previous studies, our results suggest that ecologically based barriers to gene flow and karyotypic differences may have an important role in hybrid inviability and sterility in fungi. Interestingly, hybrid sterility appeared to evolve faster than hybrid inviability in fungi. © 2012 Macmillan Publishers Limited All rights reserved. © 2012 Macmillan Publishers Limited All rights reserved.

Barbu C.,CNRS Host-Pathogen-Environment Interactions Laboratory | Dumonteil E.,Autonomous University of Yucatán | Dumonteil E.,Tulane University | Gourbiere S.,CNRS Host-Pathogen-Environment Interactions Laboratory | Gourbiere S.,University of Sussex
PLoS Neglected Tropical Diseases | Year: 2011

Background: Chagas disease is a major neglected tropical disease with deep socio-economical effects throughout Central and South America. Vector control programs have consistently reduced domestic populations of triatomine vectors, but non-domiciliated vectors still have to be controlled efficiently. Designing control strategies targeting these vectors is challenging, as it requires a quantitative description of the spatio-temporal dynamics of village infestation, which can only be gained from combinations of extensive field studies and spatial population dynamic modelling. Methodology/Principal Findings: A spatially explicit population dynamic model was combined with a two-year field study of T. dimidiata infestation dynamics in the village of Teya, Mexico. The parameterized model fitted and predicted accurately both intra-annual variation and the spatial gradient in vector abundance. Five different control strategies were then applied in concentric rings to mimic spatial design targeting the periphery of the village, where vectors were most abundant. Indoor insecticide spraying and insect screens reduced vector abundance by up to 80% (when applied to the whole village), and half of this effect was obtained when control was applied only to the 33% of households closest to the village periphery. Peri-domicile cleaning was able to eliminate up to 60% of the vectors, but at the periphery of the village it has a low effect, as it is ineffective against sylvatic insects. The use of lethal traps and the management of house attractiveness provided similar levels of control. However this required either house attractiveness to be null, or ≥5 lethal traps, at least as attractive as houses, to be installed in each household. Conclusion/Significance: Insecticide and insect screens used in houses at the periphery of the village can contribute to reduce house infestation in more central untreated zones. However, this beneficial effect remains insufficient to allow for a unique spatially targeted strategy to offer protection to all households. Most efficiently, control should combine the use of insect screens in outer zones to reduce infestation by both sylvatic and peri-domiciliated vectors, and cleaning of peri-domicile in the centre of the village where sylvatic vectors are absent. The design of such spatially mixed strategies of control offers a promising avenue to reduce the economic cost associated with the control of non-domiciliated vectors. © 2011 Barbu et al.

Gourbiere S.,CNRS Host-Pathogen-Environment Interactions Laboratory | Gourbiere S.,University of Sussex | Dorn P.,Loyola University New Orleans | Tripet F.,Keele University | Dumonteil E.,Autonomous University of Yucatán
Heredity | Year: 2012

Triatomines are hemipteran bugs acting as vectors of the protozoan parasite Trypanosoma cruzi. This parasite causes Chagas disease, one of the major parasitic diseases in the Americas. Studies of triatomine genetics and evolution have been particularly useful in the design of rational vector control strategies, and are reviewed here. The phylogeography of several triatomine species is now slowly emerging, and the struggle to reconcile the phenotypic, phylogenetic, ecological and epidemiological species concepts makes for a very dynamic field. Population genetic studies using different markers indicate a wide range of population structures, depending on the triatomine species, ranging from highly fragmented to mobile, interbreeding populations. Triatomines transmit T. cruzi in the context of complex interactions between the insect vectors, their bacterial symbionts and the parasites; however, an integrated view of the significance of these interactions in triatomine biology, evolution and in disease transmission is still lacking. The development of novel genetic markers, together with the ongoing sequencing of the Rhodnius prolixus genome and more integrative studies, will provide key tools to expanding our understanding of these important insect vectors and allow the design of improved vector control strategies. © 2012 Macmillan Publishers Limited All rights reserved.

Rascalou G.,CNRS Host-Pathogen-Environment Interactions Laboratory | Pontier D.,CNRS Biometry and Evolutionary Biology Laboratory | Menu F.,CNRS Biometry and Evolutionary Biology Laboratory | Gourbiere S.,CNRS Host-Pathogen-Environment Interactions Laboratory | Gourbiere S.,University of Sussex
PLoS ONE | Year: 2012

Vector-borne diseases represent a major public health concern in most tropical and subtropical areas, and an emerging threat for more developed countries. Our understanding of the ecology, evolution and control of these diseases relies predominantly on theory and data on pathogen transmission in large self-sustaining 'source' populations of vectors representative of highly endemic areas. However, there are numerous places where environmental conditions are less favourable to vector populations, but where immigration allows them to persist. We built an epidemiological model to investigate the dynamics of six major human vector borne-diseases in such non self-sustaining 'sink' vector populations. The model was parameterized through a review of the literature, and we performed extensive sensitivity analysis to look at the emergence and prevalence of the pathogen that could be encountered in these populations. Despite the low vector abundance in typical sink populations, all six human diseases were able to spread in 15-55% of cases after accidental introduction. The rate of spread was much more strongly influenced by vector longevity, immigration and feeding rates, than by transmission and virulence of the pathogen. Prevalence in humans remained lower than 5% for dengue, leishmaniasis and Japanese encephalitis, but substantially higher for diseases with longer duration of infection; malaria and the American and African trypanosomiasis. Vector-related parameters were again the key factors, although their influence was lower than on pathogen emergence. Our results emphasize the need for ecology and evolution to be thought in the context of metapopulations made of a mosaic of sink and source habitats, and to design vector control program not only targeting areas of high vector density, but working at a larger spatial scale. © 2012 Rascalou et al.

Holtfreter M.C.,Heinrich Heine University Düsseldorf | Mone H.,CNRS Host-Pathogen-Environment Interactions Laboratory | Mone H.,French National Center for Scientific Research | Muller-Stover I.,Heinrich Heine University Düsseldorf | And 3 more authors.
Eurosurveillance | Year: 2014

A 12 year-old boy in Germany developed urinary schistosomiasis in January 2014. He had bathed in rivers in south-eastern Corsica five months earlier. Before this case, human schistomiasis had not been reported on the island, although its vector, the snail Bulinus truncatus, locally transmitted the zoonotic Schistosoma bovis. The boy's father excreted S. haematobium ova that were not viable; the boy's three siblings had a positive serology against schistosomes. © 2007-2013. All rights reserved.

Theron A.,CNRS Host-Pathogen-Environment Interactions Laboratory
Advances in Parasitology | Year: 2015

One major challenge for parasites with complex cycles consists to succeed in the transmission from one host to the next host. To maximize the probability of encountering the right host, numerous trematode species have selected various emergence rhythms occurring during the escape of the short-lived cercariae from the mollusc host. Cercarial shedding patterns are beautiful examples of adaptation of the parasite for a successful rendezvous with its subsequent host. In this review, after an analysis of the technical and statistical aspects specific to such studies, we compile the knowledge and unresolved issues we have about the synchronization of these rhythms, their genetic support and the role of the host physiology or activity. We are also interested on how cercarial rhythmicity influences cercarial densities in waters of transmission sites and then the risk of host infection in case of schistosomiasis. Ecological significance of the inter- and intra-specific diversity of these rhythms is emphasized as well as the evolutionary implication of new chronotypes resulting from the capture of new host species and promoting reproductive isolation and alloxenic speciation. Currently, genome sequence data now available for some trematodes such as the schistosomes provide an unprecedented resource for new research approaches that should contribute identification of the genes and mechanisms involved in determining the cercarial shedding rhythms observed. © 2015 Elsevier Ltd.

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