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1.
Nat Commun ; 11(1): 2205, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32371874

RESUMO

Flaviviruses, including Zika virus (ZIKV), utilise host mRNA degradation machinery to produce subgenomic flaviviral RNA (sfRNA). In mammalian hosts, this noncoding RNA facilitates replication and pathogenesis of flaviviruses by inhibiting IFN-signalling, whereas the function of sfRNA in mosquitoes remains largely elusive. Herein, we conduct a series of in vitro and in vivo experiments to define the role of ZIKV sfRNA in infected Aedes aegypti employing viruses deficient in production of sfRNA. We show that sfRNA-deficient viruses have reduced ability to disseminate and reach saliva, thus implicating the role for sfRNA in productive infection and transmission. We also demonstrate that production of sfRNA alters the expression of mosquito genes related to cell death pathways, and prevents apoptosis in mosquito tissues. Inhibition of apoptosis restored replication and transmission of sfRNA-deficient mutants. Hence, we propose anti-apoptotic activity of sfRNA as the mechanism defining its role in ZIKV transmission.


Assuntos
Aedes/genética , Apoptose/genética , Mosquitos Vetores/genética , RNA Viral/genética , Infecção por Zika virus/genética , Zika virus/genética , Aedes/citologia , Aedes/virologia , Animais , Células Cultivadas , Chlorocebus aethiops , Regulação da Expressão Gênica , Humanos , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Mosquitos Vetores/citologia , Mosquitos Vetores/virologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA não Traduzido/genética , RNA não Traduzido/metabolismo , RNA Viral/metabolismo , Células Vero , Replicação Viral/genética , Zika virus/fisiologia , Infecção por Zika virus/transmissão , Infecção por Zika virus/virologia
2.
PLoS Negl Trop Dis ; 14(5): e0008279, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32365059

RESUMO

Dengue is a highly endemic disease in Southeast Asia and is transmitted primarily by the mosquito, Aedes aegypti. The National Capital Region (NCR) of the Philippines, or Metropolitan Manila, is a highly urbanized area that is greatly affected by this arboviral disease. Urbanization has been shown to increase the dispersal of this mosquito vector. For this reason, we conducted a fine-scale population genetic study of Ae. aegypti in this region. We collected adult Ae. aegypti mosquitoes (n = 526 individuals) within the region (n = 21 study areas) and characterized the present population structure and the genetic relatedness among mosquito populations. We genotyped 11 microsatellite loci from all sampled mosquito individuals and analyzed their genetic diversity, differentiation and structure. The results revealed low genetic differentiation across mosquito populations which suggest high gene flow and/or weak genetic drift among mosquito populations. Bayesian analysis indicated multiple genetic structures (K = 3-6), with no clear genetically distinct population structures. This result implies the passive or long-distance dispersal capability nature Ae. aegypti possibly through human-mediated transportation. The constructed dendrogram in this study describes the potential passive dispersal patterns across Metropolitan Manila. Furthermore, spatial autocorrelation analysis showed the limited and active dispersal capability (<1km) of the mosquito vector. Our findings are consistent with previous studies that investigated the genetic structure and dual (active and passive) dispersal capability of Ae. aegypti in a fine-scale highly urbanized area.


Assuntos
Aedes/classificação , Aedes/genética , Genótipo , Mosquitos Vetores/classificação , Mosquitos Vetores/genética , Aedes/crescimento & desenvolvimento , Distribuição Animal , Animais , Cidades , Genética Populacional , Técnicas de Genotipagem , Repetições de Microssatélites , Mosquitos Vetores/crescimento & desenvolvimento , Filipinas , Análise Espacial
3.
PLoS Negl Trop Dis ; 14(5): e0008216, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32384079

RESUMO

The extensive use of insecticides for vector control has led to the development of insecticide resistance in Aedes aegypti populations on a global scale, which has significantly compromised control actions. Insecticide resistance, and its underlying mechanisms, has been investigated in several countries, mostly in South American and Asian countries. In Africa, however, studies reporting insecticide resistance are rare and data on resistance mechanisms, notably knockdown resistance (kdr) mutations, is scarce. In this study, the recently described V410L kdr mutation is reported for the first time in old world Ae. aegypti populations, namely from Angola and Madeira island. Two additional kdr mutations, V1016I and F1534C, are also reported for the first time in populations from Angola and Cape Verde. Significant associations with the resistance phenotype were found for both V410L and V1016I individually as well as for tri-locus genotypes in the Angolan population. However, no association was found in Madeira island, probably due to the presence of a complex pattern of multiple insecticide resistance mechanisms in the local Ae. aegypti population. These results suggest that populations carrying the same kdr mutations may respond differently to the same insecticide, stressing the need for complementary studies when assessing the impact of kdr resistance mechanisms in the outcome of insecticide-based control strategies.


Assuntos
Aedes/efeitos dos fármacos , Aedes/genética , Proteínas de Insetos/genética , Resistência a Inseticidas , Mosquitos Vetores/efeitos dos fármacos , Mutação de Sentido Incorreto , Aedes/metabolismo , Angola , Animais , Feminino , Genótipo , Proteínas de Insetos/metabolismo , Inseticidas/farmacologia , Mosquitos Vetores/genética , Mosquitos Vetores/metabolismo , Portugal
4.
Arch Virol ; 165(8): 1769-1776, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32440701

RESUMO

South Texas has experienced local transmission of Zika virus and of other mosquito-borne viruses such as chikungunya virus and dengue virus in the last decades. Using a mosquito surveillance program in the Lower Rio Grande Valley (LRGV) and San Antonio, TX, from 2016 to 2018, we detected the presence of an insect-specific virus, cell fusing agent virus (CFAV), in the Aedes aegypti mosquito population. We tested 6,326 females and 1,249 males from the LRGV and 659 females from San Antonio for CFAV by RT-PCR using specific primers. Infection rates varied from 0 to 261 per 1,000 mosquitoes in the LRGV and 115 to 208 per 1,000 in San Antonio depending on the month of collection. Infection rates per 1,000 individuals appeared higher in females collected from BG Sentinel 2 traps compared to Autocidal Gravid Ovitraps, but the ratio of the percentage of infected pools did not differ by trap type. The natural viral load in individual males ranged from 1.25 x 102 to 5.50 x 106 RNA copies and in unfed females from 5.42 x 103 to 8.70 x 106 RNA copies. Gravid females were found to harbor fewer viral particles than males and unfed females.


Assuntos
Aedes/virologia , Flavivirus/genética , Animais , Feminino , Vírus de Insetos/genética , Masculino , Mosquitos Vetores/genética , RNA Viral/genética , Texas , Carga Viral/genética
5.
Parasitol Res ; 119(7): 2075-2083, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32458116

RESUMO

Aedes aegypti represents one of the main vectors of at least five relevant arthropod-borne viral infections in humans (i.e., Rift Valley fever, Dengue fever, Zika, chikungunya, and yellow fever) worldwide. Ae. aegypti control strategies are mostly based on using chemical insecticides (i.e., organophosphates, pyrethroids, carbamates, and organochlorines) and reducing larval sources. Furthermore, monitoring the growth activity and mapping the geographical distribution of insecticide resistance are mandatory, as recommended by the WHO. Accordingly, we conducted a study on the possible mechanism by which Ae. aegypti develops resistance to several frequently used chemical insecticides (i.e., λ-cyhalothrin, bendiocarb, cyfluthrin, deltamethrin, malathion, and permethrin) in the city of Makassar, Sulawesi, Indonesia. The results showed the progression of resistance toward the examined insecticides in Ae. aegypti populations in Makassar. The mortality rate of Ae. aegypti was less than 90%, with the highest resistance recorded against 0.75% permethrin. The molecular evaluation of the voltage-gated sodium channel gene (VGSC) showed a significant correlation of the V1016G gene mutation in the tested 0.75% permethrin-resistant Ae. aegypti phenotypes. Nevertheless, the F1534C point mutation in the VGSC gene of Ae. aegypti did not show a significant correlation with the phenotype exhibiting insecticide resistance to 0.75% permethrin. These results indicate that Ae. aegypti mosquitoes in Makassar City have developed resistance against the frequently used insecticide permethrin, which might spread to less-populated regions of Sulawesi. Therefore, we call for further entomological monitoring of insecticide resistance not only on Sulawesi but also on other closely located islands of the Indonesian archipelago to delay the spread of Ae. aegypti insecticide resistance.


Assuntos
Aedes/genética , Resistência a Inseticidas/genética , Inseticidas , Mosquitos Vetores/genética , Mutação , Canais de Sódio Disparados por Voltagem/genética , Animais , Indonésia
6.
PLoS Pathog ; 16(4): e1008433, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32282862

RESUMO

The insect bacterium Wolbachia pipientis is being introgressed into Aedes aegypti populations as an intervention against the transmission of medically important arboviruses. Here we compare Ae. aegypti mosquitoes infected with wMelCS or wAlbB to the widely used wMel Wolbachia strain on an Australian nuclear genetic background for their susceptibility to infection by dengue virus (DENV) genotypes spanning all four serotypes. All Wolbachia-infected mosquitoes were more resistant to intrathoracic DENV challenge than their wildtype counterparts. Blocking of DENV replication was greatest by wMelCS. Conversely, wAlbB-infected mosquitoes were more susceptible to whole body infection than wMel and wMelCS. We extended these findings via mosquito oral feeding experiments, using viremic blood from 36 acute, hospitalised dengue cases in Vietnam, additionally including wMel and wildtype mosquitoes on a Vietnamese nuclear genetic background. As above, wAlbB was less effective at blocking DENV replication in the abdomen compared to wMel and wMelCS. The transmission potential of all Wolbachia-infected mosquito lines (measured by the presence/absence of infectious DENV in mosquito saliva) after 14 days, was significantly reduced compared to their wildtype counterparts, and lowest for wMelCS and wAlbB. These data support the use of wAlbB and wMelCS strains for introgression field trials and the biocontrol of DENV transmission. Furthermore, despite observing significant differences in transmission potential between wildtype mosquitoes from Australia and Vietnam, no difference was observed between wMel-infected mosquitoes from each background suggesting that Wolbachia may override any underlying variation in DENV transmission potential.


Assuntos
Aedes/microbiologia , Aedes/virologia , Vírus da Dengue/fisiologia , Mosquitos Vetores/microbiologia , Mosquitos Vetores/virologia , Wolbachia/fisiologia , Aedes/genética , Aedes/metabolismo , Animais , Feminino , Masculino , Mosquitos Vetores/genética , Mosquitos Vetores/metabolismo , Controle Biológico de Vetores , Replicação Viral
7.
PLoS Pathog ; 16(4): e1008453, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32330198

RESUMO

Malaria, caused by the protozoan parasite Plasmodium and transmitted by Anopheles mosquitoes, represents a major threat to human health. Plasmodium's infection cycle in the Anopheles vector is critical for transmission of the parasite between humans. The midgut-stage bottleneck of infection is largely imposed by the mosquito's innate immune system. microRNAs (miRNAs, small noncoding RNAs that bind to target RNAs to regulate gene expression) are also involved in regulating immunity and the anti-Plasmodium defense in mosquitoes. Here, we characterized the mosquito's miRNA responses to Plasmodium infection using an improved crosslinking and immunoprecipitation (CLIP) method, termed covalent ligation of endogenous Argonaute-bound RNAs (CLEAR)-CLIP. Three candidate miRNAs' influence on P. falciparum infection and midgut microbiota was studied through transgenically expressed miRNA sponges (miR-SPs) in midgut and fat body tissues. MiR-SPs mediated conditional depletion of aga-miR-14 or aga-miR-305, but not aga-miR-8, increased mosquito resistance to both P. falciparum and P. berghei infection, and enhanced the mosquitoes' antibacterial defenses. Transcriptome analysis revealed that depletion of aga-miR-14 or aga-miR-305 resulted in an increased expression of multiple immunity-related and anti-Plasmodium genes in mosquito midguts. The overall fitness cost of conditionally expressed miR-SPs was low, with only one of eight fitness parameters being adversely affected. Taken together, our results demonstrate that targeting mosquito miRNA by conditional expression of miR-SPs may have potential for the development of malaria control through genetically engineered mosquitoes.


Assuntos
Anopheles/imunologia , Malária Falciparum/parasitologia , MicroRNAs/imunologia , Mosquitos Vetores/imunologia , Plasmodium berghei/fisiologia , Plasmodium falciparum/fisiologia , Animais , Anopheles/genética , Anopheles/parasitologia , Feminino , MicroRNAs/genética , Mosquitos Vetores/genética , Mosquitos Vetores/parasitologia , Plasmodium berghei/genética , Plasmodium berghei/imunologia , Plasmodium falciparum/genética , Plasmodium falciparum/imunologia
8.
PLoS Negl Trop Dis ; 14(4): e0008219, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32298261

RESUMO

Aedes aegypti is the primary vector of dengue, chikungunya, Zika, and urban yellow fever. Insecticides are often the most effective tools to rapidly decrease the density of vector populations, especially during arbovirus disease outbreaks. However, the intense use of insecticides, particularly pyrethroids, has selected for resistant mosquito populations worldwide. Mutations in the voltage gated sodium channel (NaV) are among the principal mechanisms of resistance to pyrethroids and DDT, also known as "knockdown resistance," kdr. Here we report studies on the origin and dispersion of kdr haplotypes in samples of Ae. aegypti from its worldwide distribution. We amplified the IIS6 and IIIS6 NaV segments from pools of Ae. aegypti populations from 15 countries, in South and North America, Africa, Asia, Pacific, and Australia. The amplicons were barcoded and sequenced using NGS Ion Torrent. Output data were filtered and analyzed using the bioinformatic pipeline Seekdeep to determine frequencies of the IIS6 and IIIS6 haplotypes per population. Phylogenetic relationships among the haplotypes were used to infer whether the kdr mutations have a single or multiple origin. We found 26 and 18 haplotypes, respectively for the IIS6 and IIIS6 segments, among which were the known kdr mutations 989P, 1011M, 1016I and 1016G (IIS6), 1520I, and 1534C (IIIS6). The highest diversity of haplotypes was found in African samples. Kdr mutations 1011M and 1016I were found only in American and African populations, 989P + 1016G and 1520I + 1534C in Asia, while 1534C was present in samples from all continents, except Australia. Based primarily on the intron sequence, IIS6 haplotypes were subdivided into two well-defined clades (A and B). Subsequent phasing of the IIS6 + IIIS6 haplotypes indicates two distinct origins for the 1534C kdr mutation. These results provide evidence of kdr mutations arising de novo at specific locations within the Ae. aegypti geographic distribution. In addition, our results suggest that the 1534C kdr mutation had at least two independent origins. We can thus conclude that insecticide selection pressure with DDT and more recently with pyrethroids is selecting for independent convergent mutations in NaV.


Assuntos
Aedes/efeitos dos fármacos , Aedes/genética , Genes de Insetos , Resistência a Inseticidas/genética , Mutação , Aedes/virologia , África , Alelos , Animais , Ásia , Austrália , Febre de Chikungunya/prevenção & controle , Febre de Chikungunya/transmissão , DNA/genética , Dengue/prevenção & controle , Dengue/transmissão , Frequência do Gene , Genótipo , Inseticidas , Mosquitos Vetores/genética , Mosquitos Vetores/virologia , América do Norte , Piretrinas , Febre Amarela/prevenção & controle , Febre Amarela/transmissão , Infecção por Zika virus/prevenção & controle , Infecção por Zika virus/transmissão
9.
PLoS Negl Trop Dis ; 14(4): e0008154, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32302303

RESUMO

BACKGROUND: Aedes aegypti is a globally distributed vector of human diseases including dengue, yellow fever, chikungunya, and Zika. Pyrethroid insecticides are the primary means of controlling adult A. aegypti populations to suppress arbovirus outbreaks, but resistance to pyrethroid insecticides has become a global problem. Mutations in the voltage-sensitive sodium channel (Vssc) gene are a major mechanism of pyrethroid resistance in A. aegypti. Vssc resistance alleles in A. aegypti commonly have more than one mutation. However, our understanding of the evolutionary dynamics of how alleles with multiple mutations arose is poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: We examined the geographic distribution and association between the common Vssc mutations (V410L, S989P, V1016G/I and F1534C) in A. aegypti by analyzing the relevant Vssc fragments in 25 collections, mainly from Asia and the Americas. Our results showed all 11 Asian populations had two types of resistance alleles: 1534C and 989P+1016G. The 1534C allele was more common with frequencies ranging from 0.31 to 0.88, while the 989P+1016G frequency ranged from 0.13 to 0.50. Four distinct alleles (410L, 1534C, 410L+1534C and 410L+1016I+1534C) were detected in populations from the Americas. The most common was 410L+1016I+1534C with frequencies ranging from 0.50 to 1.00, followed by 1534C with frequencies ranging from 0.13 to 0.50. Our phylogenetic analysis of Vssc supported multiple independent origins of the F1534C mutation. Our results indicated the 410L+1534C allele may have arisen by addition of the V410L mutation to the 1534C allele, or by a crossover event. The 410L+1016I+1534C allele was the result of one or two mutational steps from a 1534C background. CONCLUSIONS/SIGNIFICANCE: Our data corroborated previous geographic distributions of resistance mutations and provided evidence for both recombination and sequential accumulation of mutations contributing to the molecular evolution of resistance alleles in A. aegypti.


Assuntos
Aedes/genética , Alelos , Evolução Molecular , Resistência a Inseticidas/genética , Mutação , Recombinação Genética , Animais , Feminino , Haplótipos , Inseticidas/farmacologia , Masculino , Mosquitos Vetores/genética , Filogenia , Piretrinas/farmacologia
10.
PLoS One ; 15(4): e0232192, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32343725

RESUMO

The introduction of exotic disease vectors into a new habitat can drastically change the local epidemiological situation. During 2012-2015, larvae and an adult of the yellow-fever mosquito, Aedes aegypti, were captured alive at two international airports serving the Greater Tokyo Area, Japan. Because this species does not naturally distribute in this country, those mosquitoes were considered to be introduced from overseas via air-transportation. To infer the places of origin of those mosquitoes, we genotyped the 12 microsatellite loci for which the most comprehensive population genetic reference is currently available. Although clustering by Bayesian and multivariate methods both suggested that all those mosquitoes captured at the airports in Japan belonged to the Asia/Pacific populations, they were not clustered into a single cluster. Moreover, there was variation in mitochondrial cytochrome oxidase I gene (CoxI) haplotypes among mosquitoes collected in different incidents of discovery which indicated the existence of multiple maternal origins. We conclude there is little evidence to support the overwintering of Ae. aegypti at the airports; nevertheless, special attention is still needed to prevent the invasion of this prominent arbovirus vector.


Assuntos
Aedes/genética , Aeroportos , Mosquitos Vetores/genética , Aedes/classificação , Aedes/virologia , Animais , Infecções por Arbovirus/transmissão , Infecções por Arbovirus/virologia , Arbovirus/isolamento & purificação , Arbovirus/patogenicidade , Teorema de Bayes , Ecossistema , Complexo IV da Cadeia de Transporte de Elétrons/genética , Genes de Insetos , Genes Mitocondriais , Variação Genética , Genética Populacional , Genótipo , Haplótipos , Humanos , Proteínas de Insetos/genética , Repetições de Microssatélites , Mosquitos Vetores/classificação , Mosquitos Vetores/virologia , Tóquio
11.
Parasit Vectors ; 13(1): 202, 2020 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-32307003

RESUMO

BACKGROUND: Malaria vector mosquitoes acquire midgut microbiota primarily from their habitat. The homeostasis of these microbial communities plays an essential role in the mosquito longevity, the most essential factor in the mosquito vectorial capacity. Our recent study revealed that silencing genes involved in regulation of the midgut homeostasis including FN3D1, FN3D3 and GPRGr9 reduced the survival of female adult Anopheles arabiensis mosquitoes. In the present study, we investigate the stability of the gene silencing efficiency of mosquitoes reared in three different breeding conditions representing distinct larval habitat types: town brick pits in Jimma, flood pools in the rural land of Asendabo and roadside pools in Wolkite. METHODS: First-instar larvae of An. arabiensis mosquitoes were reared separately using water collected from the three breeding sites. The resulting adult females were micro-injected with dsRNA targeting the FN3D1 gene (AARA003032) and their survival was monitored. Control mosquitoes were injected with dsRNA Lacz. In addition, the load of midgut microbiota of these mosquitoes was determined using flow cytometry. RESULTS: Survival of naïve adult female mosquitoes differed between the three sites. Mosquitoes reared using water collected from brick pits and flood pools survived longer than mosquitoes reared using water collected from roadside. However, the FN3D1 gene silencing effect on survival did not differ between the three sites. CONCLUSIONS: The present study revealed that the efficacy of FN3D1 gene silencing is not affected by variation in the larval habitat. Thus, silencing this gene has potential for application throughout sub-Saharan Africa.


Assuntos
Anopheles/genética , Domínio de Fibronectina Tipo III/genética , Interferência de RNA/fisiologia , Animais , Anopheles/fisiologia , Cruzamento , Ecossistema , Larva/genética , Larva/fisiologia , Controle de Mosquitos/métodos , Mosquitos Vetores/genética , Mosquitos Vetores/fisiologia
12.
Nat Commun ; 11(1): 1425, 2020 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-32188851

RESUMO

A number of recent papers report that standing genetic variation in natural populations includes ubiquitous polymorphisms within target sites for Cas9-based gene drive (CGD) and that these "drive resistant alleles" (DRA) preclude the successful application of CGD for managing these populations. Here we report the results of a survey of 1280 genomes of the mosquitoes Anopheles gambiae, An. coluzzii, and Aedes aegypti in which we determine that ~90% of all protein-encoding CGD target genes in natural populations include at least one target site with no DRAs at a frequency of ≥1.0%. We conclude that the abundance of conserved target sites in mosquito genomes and the inherent flexibility in CGD design obviates the concern that DRAs present in the standing genetic variation of mosquito populations will be detrimental to the deployment of this technology for population modification strategies.


Assuntos
Aedes/genética , Anopheles/genética , Genoma de Inseto , Alelos , Animais , Sistemas CRISPR-Cas , Feminino , Frequência do Gene , Proteínas de Insetos/genética , Mosquitos Vetores/genética
13.
Infect Dis Poverty ; 9(1): 30, 2020 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-32183909

RESUMO

BACKGROUND: As of 2015 thousands of refugees are being hosted in temporary refugee camps in Greece. Displaced populations, travelling and living under poor conditions with limited access to healthcare are at a high risk of exposure to vector borne disease (VBD). This study sought to evaluate the risk for VBD transmission within refugee camps in Greece by analyzing the mosquito and sand fly populations present, in light of designing effective and efficient context specific vector and disease control programs. METHODS: A vector/pathogen surveillance network targeting mosquitoes and sand flies was deployed in four temporary refugee camps in Greece. Sample collections were conducted bi-weekly during June-September 2017 with the use of Centers for Disease Control (CDC) light traps and oviposition traps. Using conventional and molecular diagnostic tools we investigated the mosquito/sand fly species composition, population dynamics, pathogen infection rates, and insecticide resistance status in the major vector species. RESULTS: Important disease vectors including Anopheles sacharovi, Culex pipiens, Aedes albopictus and the Leishmania vectors Phlebotomus neglectus, P. perfiliewi and P. tobbi were recorded in the study refugee camps. No mosquito pathogens (Plasmodium parasites, flaviviruses) were detected in the analysed samples yet high sand fly Leishmania infection rates are reported. Culex pipiens mosquitoes displayed relatively high knock down resistance (kdr) mutation allelic frequencies (ranging from 41.0 to 63.3%) while kdr mutations were also detected in Ae. albopictus populations, but not in Anopheles and sand fly specimens. No diflubenzuron (DFB) mutations were detected in any of the mosquito species analysed. CONCLUSIONS: Important disease vectors and pathogens in vectors (Leishmania spp.) were recorded in the refugee camps indicating a situational risk factor for disease transmission. The Cx. pipiens and Ae. albopictus kdr mutation frequencies recorded pose a potential threat against the effectiveness of pyrethroid insecticides in these settings. In contrast, pyrethroids appear suitable for the control of Anopheles mosquitoes and sand flies and DFB for Cx. pipiens and Ae. albopictus larvicide applications. Targeted actions ensuring adequate living conditions and the establishment of integrated vector-borne disease surveillance programs in refugee settlements are essential for protecting refugee populations against VBDs.


Assuntos
Insetos Vetores/efeitos dos fármacos , Insetos Vetores/genética , Resistência a Inseticidas/genética , Leishmania , Controle de Mosquitos , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/genética , Dinâmica Populacional , Campos de Refugiados , Aedes/efeitos dos fármacos , Aedes/genética , Animais , Anopheles/efeitos dos fármacos , Anopheles/genética , Culex/efeitos dos fármacos , Culex/genética , Feminino , Grécia , Leishmania/genética , Leishmania/patogenicidade , Leishmaniose/epidemiologia , Phlebotomus/efeitos dos fármacos , Phlebotomus/genética , Psychodidae
14.
PLoS Negl Trop Dis ; 14(3): e0008130, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32130209

RESUMO

BACKGROUND: Yellow fever, dengue, chikungunya and Zika viruses are responsible for considerable morbidity and mortality in humans. Aedes aegypti and Aedes albopictus are the most important mosquito vectors involved in their transmission. Accurate identification of these species is essential for the implementation of control programs to limit arbovirus transmission, during suspected detections at ports of first entry, to delimit incursions or during presence/absence surveillance programs in regions vulnerable to invasion. We developed and evaluated simple and rapid colorimetric isothermal tests to detect these two mosquito species based on loop-mediated isothermal amplification (LAMP) targeting the ribosomal RNA internal transcribed spacer 1 (ITS1). METHODOLOGY/PRINCIPAL FINDINGS: Samples were prepared by homogenizing and heating at 99 oC for 10 min before an aliquot was added to the LAMP reaction. After 40 min incubation at 65 oC, a colour change indicated a positive result. The tests were 100% sensitive and species-specific, and demonstrated a limit of detection comparable with PCR-based detection (TaqMan chemistry). The LAMP assays were able to detect target species for various life stages tested (adult, 1st instar larva, 4th instar larva and pupa), and body components, such as legs, wings and pupal exuviae. Importantly, the LAMP assays could detect Ae. aegypti DNA in mosquitoes stored in Biogents Sentinel traps deployed in the field for 14 d. A single 1st instar Ae. aegypti larva could also be detected in a pool of 1,000 non-target 1st instar Aedes notoscriptus, thus expediting processing of ovitrap collections obtained during presence/absence surveys. A simple syringe-sponge protocol facilitated the concentration and collection of larvae from the ovitrap water post-hatch. CONCLUSIONS/SIGNIFICANCE: We describe the development of LAMP assays for species identification and demonstrate their direct application for surveillance in different field contexts. The LAMP assays described herein are useful adjuncts to laboratory diagnostic testing or could be employed as standalone tests. Their speed, ease-of-use, low cost and need for minimal equipment and training make the LAMP assays ideal for adoption in low-resource settings without the need to access diagnostic laboratory services.


Assuntos
Aedes/classificação , Aedes/crescimento & desenvolvimento , Colorimetria/métodos , Entomologia/métodos , Técnicas de Diagnóstico Molecular/métodos , Mosquitos Vetores/classificação , Mosquitos Vetores/crescimento & desenvolvimento , Técnicas de Amplificação de Ácido Nucleico/métodos , Aedes/genética , Animais , DNA Espaçador Ribossômico/genética , Feminino , Mosquitos Vetores/genética , Sensibilidade e Especificidade
15.
Emerg Microbes Infect ; 9(1): 348-365, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32041484

RESUMO

The release of modified mosquitoes to suppress/replace vectors constitutes a promising tool for vector control and disease prevention. Evidence regarding these innovative modification techniques is scarce and disperse. This work conducted a systematic review, gathering and analysing research articles from PubMed and Biblioteca Virtual em Saúde databases whose results report efficacy and non-target effects of using modified insects for disease prevention, until 2016. More than 1500 publications were screened and 349 were analysed. Only 12/3.4% articles reported field-based evidence and 41/11.7% covered modification strategies' post-release efficacy. Variability in the effective results (90/25.7%) questioned its reproducibility in different settings. We also found publications reporting reversal outcomes 38/10.9%, (e.g. post-release increase of vector population). Ecological effects were also reported, such as horizontal transfer events (54/15.5%), and worsening pathogenesis induced by natural wolbachia (10/2.9%). Present work revealed promising outcomes of modifying strategies. However, it also revealed a need for field-based evidence mainly regarding epidemiologic and long-term impact. It pointed out some eventual irreversible and important effects that must not be ignored when considering open-field releases, and that may constitute constraints to generate the missing field evidence. Present work constitutes a baseline of knowledge, offering also a methodological approach that may facilitate future updates.


Assuntos
Animais Geneticamente Modificados , Controle de Mosquitos/métodos , Mosquitos Vetores/genética , Animais , Transferência Genética Horizontal , Mosquitos Vetores/microbiologia , Wolbachia
16.
Mem Inst Oswaldo Cruz ; 115: e190390, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32049099

RESUMO

The mosquito Culex pipiens s.s. L. occurs as two bioforms that differ in physiology and behaviour affecting virus transmission cycles. To assess the occurrence of Cx. pipiens bioforms in the southernmost limit of its distribution, specimens were collected aboveground in southern Buenos Aires Province and east Patagonia, Argentina. Ten larvae and 25 adults were individually processed and identified by polymerase chain reaction (PCR) amplification of Ace-2 and CQ11 loci. Culex quinquefasciatus Say (one larva, two adults), Cx. pipiens f. molestus (one larva, one adult) and one adult of hybrid origin were identified in Buenos Aires Province; only Cx. pipiens f. molestus was recorded in Patagonia (eight larvae, 21 adults). The potential absence of bioform pipiens and its implications in arbovirus enzootic cycles is discussed.


Assuntos
Culex/fisiologia , Mosquitos Vetores/fisiologia , Distribuição Animal , Animais , Argentina , Culex/genética , Culex/virologia , Encefalite de St. Louis/transmissão , Mosquitos Vetores/genética , Mosquitos Vetores/virologia , Reação em Cadeia da Polimerase , Estações do Ano
18.
Parasitol Res ; 119(4): 1201-1208, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32036440

RESUMO

Knowledge of vector species composition and monitoring their change over time is critical to evaluate malaria transmission and assess control interventions. This is especially important in countries such as Botswana, where malaria transmission is subjected to fluctuations due to climate variability. Another important aspect that impacts vector populations is the insecticide resistance. In order to assess species composition and the presence of mutations associated with insecticide resistance, Anopheles specimens from larval samplings and indoor pyrethrum spray sheet collections were analysed. A total of 349 Anopheles were screened by morphology and PCR as belonging to the An. gambiae complex and An. funestus group. Specimens were subsequently analysed for human blood meal and Plasmodium index. Finally, knock-down resistance polymorphisms were assessed. Anopheles arabiensis accounted for the majority of specimens collected through larval (96.7%) and pyrethrum spray sheet collection (87.4%) across all sampling sites, and this species was the only one found positive for human blood and for P. falciparum. Other Anopheles species were collected in small numbers by pyrethrum spray catches, namely An. quadriannulatus, An. longipalpis type C and An. parensis. The authors speculate on changing climate patterns and their possible impact on species composition. The kdr assay revealed that Anopheles mosquitoes were homozygous wild type for both L1014F (kdr-w) and L1014S (kdr-e) mutations. These results highlight the unique vectorial role of An. arabiensis in Botswana and indicated that even with prolonged use of pyrethroids and DDT, the mosquito population has not developed kdr mutations, despite some in vivo evidence of insecticide resistance.


Assuntos
Anopheles/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Piretrinas/farmacologia , Animais , Botsuana , Feminino , Humanos , Resistência a Inseticidas/genética , Larva/efeitos dos fármacos , Malária/transmissão , Mosquitos Vetores/efeitos dos fármacos , Mosquitos Vetores/genética , Mutação , Reação em Cadeia da Polimerase
19.
Proc Natl Acad Sci U S A ; 117(7): 3711-3717, 2020 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-32015105

RESUMO

Mosquito-borne helminth infections are responsible for a significant worldwide disease burden in both humans and animals. Accordingly, development of novel strategies to reduce disease transmission by targeting these pathogens in the vector are of paramount importance. We found that a strain of Aedes aegypti that is refractory to infection by Dirofilaria immitis, the agent of canine heartworm disease, mounts a stronger immune response during infection than does a susceptible strain. Moreover, activation of the Toll immune signaling pathway in the susceptible strain arrests larval development of the parasite, thereby decreasing the number of transmission-stage larvae. Notably, this strategy also blocks transmission-stage Brugia malayi, an agent of human lymphatic filariasis. Our data show that mosquito immunity can play a pivotal role in restricting filarial nematode development and suggest that genetically engineering mosquitoes with enhanced immunity will help reduce pathogen transmission.


Assuntos
Aedes/imunologia , Aedes/parasitologia , Dirofilaria immitis/crescimento & desenvolvimento , Mosquitos Vetores/imunologia , Mosquitos Vetores/parasitologia , Aedes/genética , Animais , Proteínas de Insetos/genética , Proteínas de Insetos/imunologia , Larva/crescimento & desenvolvimento , Mosquitos Vetores/genética
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