The Composition of Midgut Bacteria in Aedes aegypti (Diptera: Culicidae) That Are Naturally Susceptible or Refractory to Dengue Viruses.
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SUBMITTER: Coatsworth H
PROVIDER: S-EPMC6276830 | biostudies-literature | 2018 Nov
REPOSITORIES: biostudies-literature
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Project description:Oral susceptibility of Aedes aegypti mosquitoes to dengue viruses varies between different Aedes species and strains. However, the midgut-specific transcriptional profile that may produce this variation is presently obscure and was the subject of our investigation. The variation in active expression between dengue-2 susceptible (SUS) and refractory (REF) mosquitoes was investigated during the first critical 96 hours after infection Transcriptional profiles were mined from respective guts using the serial analysis of gene expression technique (SAGE) and libraries constructed from midguts obtained from mosquitoes that received a dengue-2 infected blood meal (DENV-2), a non infected blood meal (naive) or a 5% sucrose meal (SM). Here we report that variation between DENV-2 infected libraries versus respective naïve libraries revealed very few transcripts that were common and statistically significant in DENV-2 infected libraries. In addition, the expression profiles among libraries displayed up regulation of antisense transcripts especially in the SUS strain. A strong proclivity towards strain-specificity in differential expression was observed, which suggested an exclusive transcription that is likely up-regulated after DENV-2 infection
2013-09-30 | GSE14384 | GEO
Project description:Oral susceptibility of Aedes aegypti mosquitoes to dengue viruses varies between different Aedes species and strains. However, the midgut-specific transcriptional profile that may produce this variation is presently obscure and was the subject of our investigation. The variation in active expression between dengue-2 susceptible (SUS) and refractory (REF) mosquitoes was investigated during the first critical 96 hours after infection Transcriptional profiles were mined from respective guts using the serial analysis of gene expression technique (SAGE) and libraries constructed from midguts obtained from mosquitoes that received a dengue-2 infected blood meal (DENV-2), a non infected blood meal (naive) or a 5% sucrose meal (SM). Here we report that variation between DENV-2 infected libraries versus respective naïve libraries revealed very few transcripts that were common and statistically significant in DENV-2 infected libraries. In addition, the expression profiles among libraries displayed up regulation of antisense transcripts especially in the SUS strain. A strong proclivity towards strain-specificity in differential expression was observed, which suggested an exclusive transcription that is likely up-regulated after DENV-2 infection Thirty Aedes aegypti female mosquitoes aged 4-5 days were transferred to 500 ml paper cups and offered a 5% sucrose meal (SM), a naïve blood meal or a dengue-2 (JAM 1409 strain) infectious blood meal, using standard artificial membrane feeders. Fully engorged females were isolated and maintained on a 5% sucrose solution ad libitum at 26oC and relative humidity till dissection
2013-09-30 | E-GEOD-14384 | biostudies-arrayexpress
Project description:BackgroundAedes aegypti is the primary mosquito vector for dengue virus (DENV) worldwide. Infectivity of dengue virus varies among natural populations of this mosquito. How A. aegypti responds to DENV infection relative to which genes and associated pathways contribute to its differential susceptibility as a vector is not well defined.Methods/principal findingsHere, we used custom cDNA microarrays to identify groups of genes that were differentially expressed in midgut tissues between susceptible and refractory strains in a highly time specific manner. While genes involved in protein processing in the endoplasmic reticulum, mRNA surveillance, and the proteasome were significantly up-regulated in the susceptible strain, several metabolic processes including glycolysis, glycan biosynthesis and Wnt pathway were active in the refractory strain. In addition, several key signaling genes were expressed as common responsive genes in both susceptible and refractory mosquitoes that may be necessary for signal transduction to trigger the appropriate host response to the viral infection. These are coordinately expressed in the form of tight gene networks and expression clusters that may be necessary to differentially contribute to the progression of dengue infection between the two strains.ConclusionsOur data show that highly correlated differential expression of responsive genes throughout the post infection period in A. aegypti midgut tissues is necessary for a coordinated transcriptional response of the mosquito genes to host or defend the viral infection.
| S-EPMC3471866 | biostudies-literature
Project description:This study was aimed to identify the chemical compounds of Aedes aegypti that can be potentially used to develop pheromone-based vector control methods. In this study, we compared the chemical compounds collected from the organs of mosquitoes at different developmental stages in the life cycle. We also compared the composition and amount of extracts from the different tissues of male and female adult mosquito. Interestingly, we found large amount of C17-C20 ethyl and methyl esters in the wings of female and antennae of male mosquito. We also found that isopropyl esters, dodelactone, octadecenoic acid and medium-chain fatty acid increase drastically during the late larval stage (L4). Old adult mosquitoes showed remarkable increase in production of C16:1 and C18:1 methyl esters, as a first example of chemical signatures specifically associated with aging in the animals. This knowledge may open the ground to find new behaviorally-important molecules with the ability to control Aedes specifically.
| S-EPMC6559988 | biostudies-literature
Project description:Aedes aegypti is one of the species most favored by changes in the environment caused by urbanization. Its abundance increases rapidly in the face of such changes, increasing the risk of disease transmission. Previous studies have shown that mosquito species that have adapted to anthropogenic environmental changes benefit from urbanization and undergo population expansion. In light of this, we used microsatellite markers to explore how urbanization processes may be modulating Ae. aegypti populations collected from three areas with different levels of urbanization in the city of São Paulo, Brazil. Specimens were collected at eleven sites in three areas with different degrees of urbanization in the city of São Paulo: conserved, intermediate and urbanized. Ten microsatellite loci were used to characterize the populations from these areas genetically. Our findings suggest that as urbanized areas grow and the human population density in these areas increases, Ae. aegypti populations undergo a major population expansion, which can probably be attributed to the species' adaptability to anthropogenic environmental changes. Our findings reveal a robust association between, on the one hand, urbanization processes and densification of the human population and, on the other, Ae. aegypti population structure patterns and population expansion. This indicates that this species benefits from anthropogenic effects, which are intensified by migration of the human population from rural to urban areas, increasing the risk of epidemics and disease transmission to an ever-increasing number of people.
| S-EPMC5607186 | biostudies-literature
Project description:BackgroundLow-income urban communities in the tropics often lack sanitary infrastructure and are overcrowded, favoring Aedes aegypti proliferation and arboviral transmission. However, as Ae. aegypti density is not spatially homogeneous, understanding the role of specific environmental characteristics in determining vector distribution is critical for planning control interventions. The objectives of this study were to identify the main habitat types for Ae. Aegypti, assess their spatial densities to identify major hotspots of arbovirus transmission over time and investigate underlying factors in a low-income urban community in Salvador, Brazil. We also tested the field-collected mosquitoes for arboviruses.MethodsA series of four entomological and socio-environmental surveys was conducted in a random sample of 149 households and their surroundings between September 2019 and April 2021. The surveys included searching for potential breeding sites (water-containing habitats) and for Ae. aegypti immatures in them, capturing adult mosquitoes and installing ovitraps. The spatial distribution of Ae. aegypti density indices were plotted using kernel density-ratio maps, and the spatial autocorrelation was assessed for each index. Visual differences on the spatial distribution of the Ae. aegypti hotspots were compared over time. The association of entomological findings with socio-ecological characteristics was examined. Pools of female Ae. aegypti were tested for dengue, Zika and chikungunya virus infection.ResultsOverall, 316 potential breeding sites were found within the study households and 186 in the surrounding public spaces. Of these, 18 (5.7%) and 7 (3.7%) harbored a total of 595 and 283 Ae. aegypti immatures, respectively. The most productive breeding sites were water storage containers within the households and puddles and waste materials in public areas. Potential breeding sites without cover, surrounded by vegetation and containing organic matter were significantly associated with the presence of immatures, as were households that had water storage containers. None of the entomological indices, whether based on immatures, eggs or adults, detected a consistent pattern of vector clustering in the same areas over time. All the mosquito pools were negative for the tested arboviruses.ConclusionsThis low-income community displayed high diversity of Ae. aegypti habitats and a high degree of heterogeneity of vector abundance in both space and time, a scenario that likely reflects other low-income communities. Improving basic sanitation in low-income urban communities through the regular water supply, proper management of solid wastes and drainage may reduce water storage and the formation of puddles, minimizing opportunities for Ae. aegypti proliferation in such settings.
| S-EPMC10163576 | biostudies-literature
Project description:BackgroundDengue virus (DENV) is the arbovirus with the highest incidence in New Caledonia and in the South Pacific region. In 2012-2014, a major DENV-1 outbreak occurred in New Caledonia. The only known vector of DENV in New Caledonia is Aedes aegypti but no study has yet evaluated the competence of New Caledonia Ae. aegypti populations to transmit DENV. This study compared the ability of field-collected Ae. aegypti from different locations in New Caledonia to transmit the DENV-1 responsible for the 2012-2014 outbreak. This study also aimed to compare the New Caledonia results with the vector competence of Ae. aegypti from French Polynesia as these two French countries have close links, including arbovirus circulation.MethodsThree wild Ae. aegypti populations were collected in New Caledonia and one in French Polynesia. Female mosquitoes were orally exposed to DENV-1 (106 FFU/ml). Mosquito bodies (thorax and abdomen), heads and saliva were analyzed to measure infection, dissemination, transmission rates and transmission efficiency, at 7, 14 and 21 days post-infection (dpi), respectively.ResultsDENV-1 infection rates were heterogeneous, but dissemination rates were high and homogenous among the three Ae. aegypti populations from New Caledonia. Despite this high DENV-1 dissemination rate, the transmission rate, and therefore the transmission efficiency, observed were low. Aedes aegypti population from New Caledonia was less susceptible to infection and had lower ability to transmit DENV-1 than Ae. aegypti populations from French Polynesia.ConclusionThis study suggests that even if susceptible to infection, the New Caledonian Ae. aegypti populations were moderately competent vectors for DENV-1 strain from the 2012-2014 outbreak. These results strongly suggest that other factors might have contributed to the spread of this DENV-1 strain in New Caledonia and in the Pacific region.
| S-EPMC5551013 | biostudies-literature
Project description:Zika virus (ZIKV) is a Flavivirus (Flaviviridae) transmitted to humans mainly by the bite of an infected Aedes mosquitoes. Aedes aegypti is the primary epidemic vector of ZIKV and Ae. albopictus, the secondary one. However, the epidemiological role of both Aedes species in Central Africa where Ae. albopictus was recently introduced is poorly characterized. Field-collected strains of Ae. aegypti and Ae. albopictus from different ecological settings in Central Africa were experimentally infected with a ZIKV strain isolated in West Africa. Mosquitoes were analysed at 14- and 21-days post-exposure. Both Ae. aegypti and Ae. albopictus were able to transmit ZIKV but with higher overall transmission efficiency for Ae. aegypti (57.9%) compared to Ae. albopictus (41.5%). In addition, disseminated infection and transmission rates for both Ae. aegypti and Ae. albopictus varied significantly according to the location where they were sampled from. We conclude that both Ae. aegypti and Ae. albopictus are able to transmit ZIKV and may intervene as active Zika vectors in Central Africa. These findings could contribute to a better understanding of the epidemiological transmission of ZIKV in Central Africa and develop suitable strategy to prevent major ZIKV outbreaks in this region.
| S-EPMC7117767 | biostudies-literature
Project description:Several studies have shown that American genotype dengue 2 viruses (DENV2) have reduced viral fitness in the mosquito vector, Aedes aegypti, compared to other DENV2 genotypes. Diminished replication efficiency or inability to efficiently traverse membrane barriers encompassing organs such as the midgut or salivary glands are considered major factors negatively impacting viral fitness in the mosquito.We analyzed the vector competence of Ae. aegypti for two American DENV2 strains, QR94 and PR159 originating from Mexico and Puerto-Rico, respectively. Both strains infected mosquito midguts following acquisition of infectious bloodmeals. However, DENV2-QR94 and DENV2-PR159 poorly disseminated from the midgut at 7 or 14 days post-bloodmeal (pbm). We detected one virus isolate, EM33, among 31 DENV2-QR94 infected mosquitoes, and one isolate, EM41, among 121 DENV2-PR159 infected mosquitoes, generating high virus titers in mosquito carcasses at 7 days pbm. In oral challenge experiments, EM33 and EM41 showed midgut dissemination rates of 40-50%. Replication efficiency of EM41 in secondary mosquito tissue was similar to that of a dissemination-competent control strain, whereas the replication efficiency of EM33 was significantly lower than that of the control virus. The genome sequence of DENV2-QR94 encoded seven unique amino acids (aa), which were not found in 100 of the most closely related DENV2 strains. EM33 had one additional aa change, E202K, in the E protein. DENV2-PR159 encoded four unique aa residues, one of them E202K, whereas EM41 had two additional aa substitutions, Q77E in the E protein and E93D in NS3.Our results indicate that the midgut of Ae. aegypti acts as a selective sieve for DENV2 in which genetically distinct, dissemination-competent virus variants are rapidly selected from the viral quasispecies to be transmitted to vertebrates.
| S-EPMC3751248 | biostudies-literature
Project description:Graphical abstract A laboratory strain of Aedes aegypti (L) was subjected repeatedly to larval selection pressure with two bacterial insecticides, spinosad (Saccharopolyspora spinosa) and bacilod (Bacillus thuringiensis israelensis). The results indicated that the mosquito Ae. aegypti acquired low resistance to spinosad and bacilod by about 3.1 and 2.4-fold, respectively, due to selection pressure for fifteen successive generations. The slope values of the selected strains were increased gradually from one generation to the next, indicating moderate homogeneity between individuals in their response to the test bio-insecticide. Moreover, larval selection with current bacterial bioinsecticides prolonged the time required to digest a blood meal. It showed an evident decrease in the reproductive potential of adult mosquitoes surviving selected larvae.
| S-EPMC10458291 | biostudies-literature