Genetic diversity and phylogeny of Aedes aegypti, the main arbovirus vector in the Pacific

Background The Pacific region is an area unique in the world, composed of thousands of islands with differing climates and environments. The spreading and establishment of the mosquito Aedes aegypti in these islands might be linked to human migration. Ae. aegypti is the major vector of arboviruses (dengue, chikungunya and Zika viruses) in the region. The intense circulation of these viruses in the Pacific during the last decade led to an increase of vector control measures by local health authorities. The aim of this study is to analyze the genetic relationships among Ae. aegypti populations in this region. Methodology/Principal Finding We studied the genetic variability and population genetics of 270 Ae. aegypti, sampled from 9 locations in New Caledonia, Fiji, Tonga and French Polynesia by analyzing nine microsatellites and two mitochondrial DNA regions (CO1 and ND4). Microsatellite markers revealed heterogeneity in the genetic structure between the western, central and eastern Pacific island countries. The microsatellite markers indicate a statistically moderate differentiation (FST = 0.136; P < = 0.001) in relation to island isolation. A high degree of mixed ancestry can be observed in the most important towns (e.g. Noumea, Suva and Papeete) compared with the most isolated islands (e.g. Ouvea and Vaitahu). Phylogenetic analysis indicated that most of samples are related to Asian and American specimens. Conclusions/Significance Our results suggest a link between human migrations in the Pacific region and the origin of Ae. aegypti populations. The genetic pattern observed might be linked to the island isolation and to the different environmental conditions or ecosystems

Чорноморсько-середземноморський коридор упродовж останніх 30 тис. років

Висунуто багато гіпотез щодо реконструкцій давнього навколишнього середовища та палеоклімату Чорноморсько-Середземноморського регіону й визначення факторів, що спричинили динаміку рівня моря. Цій проблематиці було присвячено Другу пленарну конференцію та польові екскурсії, згідно з Проектом IGCP-521 «Чорноморсько-Середземноморський коридор упродовж останніх 30 тис. років: зміни рівня моря та адаптація людини», що відбулися 20—28 серпня 2006 р. у м. Одеса на базі Одеського національного університету ім. І.І. Мечникова (ОНУ). Роботи здійснювалися під егідою ЮНЕСКО, IUGS, IGCP, INQUA

Deciphering the Leishmania exoproteome : what we know and what we can learn

Parasitic protozoa of the genus Leishmania are the causative agents of leishmaniasis. Survival and transmission of these parasites in their different hosts require membrane-bound or extracellular factors to interact with and modify their host environments. Over the last decade, several approaches have been applied to study all the extracellular proteins exported by an organism at a particular time or stage in its life cycle and under defined conditions, collectively termed the secretome or the exoproteome. In this review, we focus on emerging data shedding light on the secretion mechanisms involved in the production of the Leishmania exoproteome. We also describe other methodologies currently available that could be used to analyse the Leishmania exoproteome. Understanding the complexity of the Leishmania exoproteome is a key component to elucidating the mechanisms used by these parasites for exporting proteins to the extracellular space during its life cycle. Given the importance of extracellular factors, a detailed knowledge of the Leishmania exoproteome may provide novel targets for rational drug design and/or a source of antigens for vaccine development

An experimental approach for the identification of conserved secreted proteins in trypanosomatids

Extracellular factors produced by Leishmania spp., Trypanosoma cruzi, and Trypanosoma brucei are important in the host-parasite relationship. Here, we describe a genome-based approach to identify putative extracellular proteins conserved among trypanosomatids that are likely involved in the classical secretory pathway. Potentially secreted proteins were identified by bioinformatic analysis of the T. cruzi genome. A subset of thirteen genes encoding unknown proteins with orthologs containing a signal peptide sequence in L. infantum, L. major, and T. brucei were transfected into L. infantum. Tagged proteins detected in the extracellular medium confirmed computer predictions in about 25% of the hits. Secretion was confirmed for two L. infantum orthologs proteins using the same experimental system. Infectivity studies of transgenic Leishmania parasites suggest that one of the secreted proteins increases parasite replication inside macrophages. This methodology can identify conserved secreted proteins involved in the classical secretory pathway, and they may represent potential virulence factors in trypanosomatids

An Experimental Approach for the Identification of Conserved Secreted Proteins in Trypanosomatids

Extracellular factors produced by Leishmania spp., Trypanosoma cruzi, and Trypanosoma brucei are important in the host-parasite relationship. Here, we describe a genome-based approach to identify putative extracellular proteins conserved among trypanosomatids that are likely involved in the classical secretory pathway. Potentially secreted proteins were identified by bioinformatic analysis of the T. cruzi genome. A subset of thirteen genes encoding unknown proteins with orthologs containing a signal peptide sequence in L. infantum, L. major, and T. brucei were transfected into L. infantum. Tagged proteins detected in the extracellular medium confirmed computer predictions in about 25% of the hits. Secretion was confirmed for two L. infantum orthologs proteins using the same experimental system. Infectivity studies of transgenic Leishmania parasites suggest that one of the secreted proteins increases parasite replication inside macrophages. This methodology can identify conserved secreted proteins involved in the classical secretory pathway, and they may represent potential virulence factors in trypanosomatids

Specific human antibody responses to Aedes aegypti and Aedes polynesiensis saliva: A new epidemiological tool to assess human exposure to disease vectors in the Pacific.

BACKGROUND:Aedes mosquitoes severely affect the health and wellbeing of human populations by transmitting infectious diseases. In French Polynesia, Aedes aegypti is the main vector of dengue, chikungunya and Zika, and Aedes polynesiensis the primary vector of Bancroftian filariasis and a secondary vector of arboviruses. Tools for assessing the risk of disease transmission or for measuring the efficacy of vector control programmes are scarce. A promising approach to quantify the human-vector contact relies on the detection and the quantification of antibodies directed against mosquito salivary proteins. METHODOLOGY/PRINCIPAL FINDINGS:An ELISA test was developed to detect and quantify the presence of immunoglobulin G (IgG) directed against proteins from salivary gland extracts (SGE) of Ae. aegypti and Ae. polynesiensis in human populations exposed to either species, through a cross-sectional study. In Tahiti and Moorea islands where Ae. aegypti and Ae. polynesiensis are present, the test revealed that 98% and 68% of individuals have developed IgG directed against Ae. aegypti and Ae. polynesiensis SGE, respectively. By comparison, ELISA tests conducted on a cohort of people from metropolitan France, not exposed to these Aedes mosquitoes, indicated that 97% of individuals had no IgG directed against SGE of either mosquito species. The analysis of additional cohorts representing different entomological Aedes contexts showed no ELISA IgG cross-reactivity between Ae. aegypti and Ae. polynesiensis SGE. CONCLUSIONS/SIGNIFICANCE:The IgG response to salivary gland extracts seems to be a valid and specific biomarker of human exposure to the bites of Ae. aegypti and Ae. polynesiensis. This new immuno-epidemiological tool will enhance our understanding of people exposure to mosquito bites, facilitate the identification of areas where disease transmission risk is high and permit to evaluate the efficacy of novel vector control strategies in Pacific islands and other tropical settings

Antibody responses to <i>Ae</i>. <i>aegypti</i> and <i>Ae</i>. <i>polynesiensis</i> SGE in French Polynesian residents.

<p>The figure presents the individual IgG responses (ΔOD) against <i>Ae</i>. <i>aegypti</i> (A) and <i>Ae</i>. <i>polynesiensis</i> (B) SGE in metropolitan France (n = 66) and in Tahiti and Moorea islands (French Polynesia, n = 47) residents. Each triangle or dot represents an individual sample and the horizontal bar indicates the median value. The dotted lines correspond to the positivity thresholds calculated from the cohort of metropolitan French residents, not exposed to these <i>Aedes</i> species (0.16 for <i>Ae</i>. <i>aegypti</i> and 0.13 for <i>Ae</i>. <i>polynesiensis</i>). The percentage of responders (positive samples) in the Tahiti-Moorea cohort is shown above the plot. The non-parametric Mann-Whitney test was used to compare groups.</p