Intracellular Interactions between Arboviruses and Wolbachia in Aedes aegypti

Aedes aegypti is inherently susceptible to arboviruses. The geographical expansion of this vector host species has led to the persistence of Dengue, Zika and Chikungunya human infections. These viruses take advantage of the mosquito’s cell to create an environment conducive for their growth. Arboviral infection triggers transcriptomic and protein dysregulation in Ae. aegypti and in effect, host antiviral mechanisms are compromised. Currently, there are no existing vaccines able to protect human hosts from these infections and thus, vector control strategies such as Wolbachia mass release program is regarded as a viable option. Considerable evidence demonstrates how the presence of Wolbachia interferes with arboviruses by decreasing cellular components vital for the pathogen and strengthening antiviral host responses. However, variation in the magnitude of Wolbachia’s viral inhibition that is neither due to strain nor density has been observed. Furthermore, the cellular mechanisms involved in the endosymbiont’s pathogen-blocking differs among hosts. This prompts the need to explore the cellular interactions between Ae. aegypti-arboviruses-Wolbachia and how these interactions overall affect the mosquito’s cell. Understanding what happens at the cellular and molecular level will provide evidence on the sustainability of Wolbachia vector control.

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Intracellular Interactions Between Arboviruses and Wolbachia in Aedes aegypti

Frontiers in Cellular and Infection Microbiology ◽

10.3389/fcimb.2021.690087 ◽

2021 ◽

Vol 11 ◽

Author(s):

Jerica Isabel L. Reyes ◽

Yasutsugu Suzuki ◽

Thaddeus Carvajal ◽

Maria Nilda M. Muñoz ◽

Kozo Watanabe

Keyword(s):

Aedes Aegypti ◽

Vector Control ◽

Host Species ◽

Control Strategies ◽

Cytoskeletal Proteins ◽

Cellular Interactions ◽

Cellular Mechanisms ◽

Cellular Regeneration ◽

Release Program ◽

Human Infections

Aedes aegypti is inherently susceptible to arboviruses. The geographical expansion of this vector host species has led to the persistence of Dengue, Zika, and Chikungunya human infections. These viruses take advantage of the mosquito’s cell to create an environment conducive for their growth. Arboviral infection triggers transcriptomic and protein dysregulation in Ae. aegypti and in effect, host antiviral mechanisms are compromised. Currently, there are no existing vaccines able to protect human hosts from these infections and thus, vector control strategies such as Wolbachia mass release program is regarded as a viable option. Considerable evidence demonstrates how the presence of Wolbachia interferes with arboviruses by decreasing host cytoskeletal proteins and lipids essential for arboviral infection. Also, Wolbachia strengthens host immunity, cellular regeneration and causes the expression of microRNAs which could potentially be involved in virus inhibition. However, variation in the magnitude of Wolbachia’s pathogen blocking effect that is not due to the endosymbiont’s density has been recently reported. Furthermore, the cellular mechanisms involved in this phenotype differs depending on Wolbachia strain and host species. This prompts the need to explore the cellular interactions between Ae. aegypti-arboviruses-Wolbachia and how different Wolbachia strains overall affect the mosquito’s cell. Understanding what happens at the cellular and molecular level will provide evidence on the sustainability of Wolbachia vector control.

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Predicting Aedes aegypti infestation using landscape and thermal features

Scientific Reports ◽

10.1038/s41598-020-78755-8 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Camila Lorenz ◽

Marcia C. Castro ◽

Patricia M. P. Trindade ◽

Maurício L. Nogueira ◽

Mariana de Oliveira Lage ◽

...

Keyword(s):

Remote Sensing ◽

Aedes Aegypti ◽

Vector Control ◽

Land Surface ◽

Urban Areas ◽

Negative Binomial ◽

Control Strategies ◽

Winter Season ◽

Landsat 8 ◽

Thermal Features

AbstractIdentifying Aedes aegypti breeding hotspots in urban areas is crucial for the design of effective vector control strategies. Remote sensing techniques offer valuable tools for mapping habitat suitability. In this study, we evaluated the association between urban landscape, thermal features, and mosquito infestations. Entomological surveys were conducted between 2016 and 2019 in Vila Toninho, a neighborhood of São José do Rio Preto, São Paulo, Brazil, in which the numbers of adult female Ae. aegypti were recorded monthly and grouped by season for three years. We used data from 2016 to 2018 to build the model and data from summer of 2019 to validate it. WorldView-3 satellite images were used to extract land cover classes, and land surface temperature data were obtained using the Landsat-8 Thermal Infrared Sensor (TIRS). A multilevel negative binomial model was fitted to the data, which showed that the winter season has the greatest influence on decreases in mosquito abundance. Green areas and pavements were negatively associated, and a higher cover of asbestos roofs and exposed soil was positively associated with the presence of adult females. These features are related to socio-economic factors but also provide favorable breeding conditions for mosquitos. The application of remote sensing technologies has significant potential for optimizing vector control strategies, future mosquito suppression, and outbreak prediction.

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Workshop for priority-setting in Aedes aegypti control interventions in Latin America and the Caribbean: a policy dialogue

Cadernos de Saúde Pública ◽

10.1590/0102-311x00092918 ◽

2019 ◽

Vol 35 (4) ◽

Author(s):

Agustin Ciapponi ◽

Ariel Bardach ◽

Andrea Alcaraz ◽

María Belizán ◽

Daniel Jones ◽

...

Keyword(s):

Latin America ◽

Aedes Aegypti ◽

Vector Control ◽

Priority Setting ◽

Mosquito Control ◽

Control Strategies ◽

Policy Dialogue ◽

Regional Research ◽

Deliberative Process ◽

The Caribbean

This article presents the results of a dialogue between decision-makers and experts in Latin America and the Caribbean on priority-setting for interventions and studies on Aedes aegypti control. The article is part of a project that included a systematic review of mosquito control strategies and a qualitative study with key informants from the region. Using a collective deliberative process assisted by the results of the above-mentioned projects, a list of priorities was developed by consensus for the implementation of vector control strategies and the development of key regional research lines. It was agreed that the best strategy is integrated vector management, divided into: (a) chemical control; (b) biological control; (c) environmental management; (d) community participation; and (e) integrated surveillance. The workshop highlighted the crucial role of government leadership and inter-sector coordination between government agencies and civil society stakeholders. The proposed priorities for research lines were: Ae. aegypti vector competence and associated factors; community components of interventions; incorporation of technology into vector control and monitoring; most efficient modalities of integrated surveillance; entomological indicators with the best predictive capacity; and resistance to insecticides. The policy dialogue methodology allowed validating and enriching the results of other levels of research, besides establishing priorities for regional research and control strategies.

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Phenotypic and haplotypic profiles of insecticide resistance in populations of Aedes aegypti larvae (Diptera: Culicidae) from central Lao PDR

Tropical Medicine and Health ◽

10.1186/s41182-021-00321-3 ◽

2021 ◽

Vol 49 (1) ◽

Author(s):

Takaki Shimono ◽

Seiji Kanda ◽

Pheophet Lamaningao ◽

Yuki Murakami ◽

Andrew Waleluma Darcy ◽

...

Keyword(s):

Aedes Aegypti ◽

Insecticide Resistance ◽

Vector Control ◽

Pyrethroid Resistance ◽

Control Strategies ◽

Lao Pdr ◽

Resistance Mechanisms ◽

Cytochrome P450 Monooxygenases ◽

Bacillus Thuringiensis Israelensis ◽

Vector Management

Abstract Background Aedes aegypti, which is widely distributed in the Lao People’s Democratic Republic (PDR), is the primary vector of arboviral diseases. Chemical insecticides have been intensively used to eliminate mosquito-borne diseases, resulting in the development of insecticide resistance. However, little is known about the insecticide resistance of mosquito populations in Lao PDR and the mechanisms responsible for it, which have important implications for vector management programs. Here, we examined the phenotypic and haplotypic profiles of insecticide resistance in populations of Ae. aegypti larvae from central Lao PDR. Methods Ae. aegypti larvae were collected from four sites in Lao PDR, and their susceptibility to temephos, deltamethrin, permethrin, and Bacillus thuringiensis israelensis (Bti) was tested using larval bioassays. Synergistic tests were also conducted to evaluate the activity of insecticide-metabolizing enzymes in the larvae. Deltamethrin-resistant and Deltamethrin-susceptible larvae were then genotyped for knockdown resistance (kdr) mutations to determine the associations between each genotype and resistance. Results Ae. aegypti larvae from central Lao PDR were considered to be “resistant” (<98% mortality) to organophosphates and pyrethroids. The bio-insecticide Bti remains effective against such larvae. The resistance mechanisms of Ae. aegypti larvae were found to vary among populations, especially for pyrethroid resistance. Kdr mutations were significantly associated with deltamethrin resistance in Ae. aegypti from the Xaythany population. In contrast, synergist assays with piperonyl butoxide suggested that cytochrome P450 monooxygenases played an important role in the resistance seen in the Khounkham and Thakhek populations. Conclusion This study obtained information that will aid the design and implementation of insecticide-based vector management of Ae. aegypti in central Lao PDR. Ae. aegypti larvae from central Lao PDR were highly susceptible to Bti, while they were resistant to temephos at a diagnostic dose of 0.0286 mg/L. Given the limited number of insecticides that are approved for vector control, it is important to alternate between temephos and other larvicides, such as Bti and pyriproxyfen. The differences in pyrethroid resistance mechanisms seen among the Ae. aegypti populations highlight the need to tailor vector-control strategies to each region to increase the success of dengue control in Lao PDR.

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Spatial pattern evolution of Aedes aegypti breeding sites in an Argentinean city without a dengue vector control programme

Geospatial health ◽

10.4081/gh.2016.471 ◽

2016 ◽

Vol 11 (3) ◽

Cited By ~ 8

Author(s):

Manuel O. Espinosa ◽

Francisco Polop ◽

Camilo H. Rotela ◽

Marcelo Abril ◽

Carlos M. Scavuzzo

Keyword(s):

Aedes Aegypti ◽

Vector Control ◽

Urban Areas ◽

Control Strategies ◽

Dengue Vector ◽

Risk Area ◽

Niche Model ◽

Temporal Behaviour ◽

Breeding Sites ◽

Time Dynamics

The main objective of this study was to obtain and analyse the space-time dynamics of Aedes aegypti breeding sites in Clorinda City, Formosa Province, Argentina coupled with landscape analysis using the maximum entropy approach in order to generate a dengue vector niche model. In urban areas, without vector control activities, 12 entomologic (larval) samplings were performed during three years (October 2011 to October 2014). The entomologic surveillance area represented 16,511 houses. Predictive models for Aedes distribution were developed using vector breeding abundance data, density analysis, clustering and geoprocessing techniques coupled with Earth observation satellite data. The spatial analysis showed a vector spatial distribution pattern with clusters of high density in the central region of Clorinda with a well-defined high-risk area in the western part of the city. It also showed a differential temporal behaviour among different areas, which could have implications for risk models and control strategies at the urban scale. The niche model obtained for Ae. aegypti, based on only one year of field data, showed that 85.8% of the distribution of breeding sites is explained by the percentage of water supply (48.2%), urban distribution (33.2%), and the percentage of urban coverage (4.4%). The consequences for the development of control strategies are discussed with reference to the results obtained using distribution maps based on environmental variables.

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Two Haplotypes of Aedes aegypti Detected by ND4 Mitochondrial Marker in Three Regions of Ecuador

Insects ◽

10.3390/insects12030200 ◽

2021 ◽

Vol 12 (3) ◽

pp. 200

Author(s):

Patricio Ponce ◽

Sofía Muñoz-Tobar ◽

Andrés Carrazco-Montalvo ◽

Stephany D. Villota ◽

Josefina Coloma ◽

...

Keyword(s):

Genetic Structure ◽

Aedes Aegypti ◽

Vector Control ◽

Control Strategies ◽

Mitochondrial Gene ◽

Control Programs ◽

Key Factor ◽

Tropical Areas ◽

The One ◽

Haplotype 1

Aedes aegypti, also known as the yellow fever mosquito, is the main vector of several arboviruses. In Ecuador, dengue and chikungunya are the most prevalent mosquito-borne diseases. Hence, there is a need to understand the population dynamics and genetic structure of the vector in tropical areas for a better approach towards effective vector control programs. This study aimed to assess the genetic diversity of Ae. aegypti, through the analyses of the mitochondrial gene ND4, using a combination of phylogenetic and population genetic structure from 17 sites in Ecuador. Results showed two haplotypes in the Ecuadorian populations of Ae. aegypti. Haplotype 1 was closely related to Ae. aegypti reported from America, Asia, and West Africa. Haplotype 2 was only related to samples from America. The sampled vectors from the diverse localities showed low nucleotide diversity (π = 0–0.01685) and genetic differentiation (FST = 0.152). AMOVA analyses indicated that most of the variation (85–91%) occurred within populations, suggesting that geographical barriers have little effect on the genetic structure of Ecuadorian populations of Ae. aegypti. These results agree with the one main population (K = 1) detected by Structure. Vector genetic identity may be a key factor in the planning of vector control strategies.

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Insecticide resistance status and mechanisms in Aedes aegypti populations from Senegal

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0009393 ◽

2021 ◽

Vol 15 (5) ◽

pp. e0009393

Author(s):

Ndeye Marie Sene ◽

Konstantinos Mavridis ◽

El Hadji Ndiaye ◽

Cheikh Tidiane Diagne ◽

Alioune Gaye ◽

...

Keyword(s):

Aedes Aegypti ◽

Insecticide Resistance ◽

Vector Control ◽

Pyrethroid Resistance ◽

Control Strategies ◽

Resistance Mechanisms ◽

Northern Region ◽

Target Site ◽

Limited Information ◽

Resistance Mutations

Aedes aegypti is the main epidemic vector of arboviruses in Africa. In Senegal, control activities are mainly limited to mitigation of epidemics, with limited information available for Ae. aegypti populations. A better understanding of the current Ae. aegypti susceptibility status to various insecticides and relevant resistance mechanisms involved is needed for the implementation of effective vector control strategies. The present study focuses on the detection of insecticide resistance and reveals the related mechanisms in Ae. aegypti populations from Senegal. Bioassays were performed on Ae. aegypti adults from nine Senegalese localities (Matam, Louga, Barkedji, Ziguinchor, Mbour, Fatick, Dakar, Kédougou and Touba). Mosquitoes were exposed to four classes of insecticides using the standard WHO protocols. Resistance mechanisms were investigated by genotyping for pyrethroid target site resistance mutations (V1016G, V1016I, F1534C and S989P) and measuring gene expression levels of key detoxification genes (CYP6BB2, CYP9J26, CYP9J28, CYP9J32, CYP9M6, CCEae3a and GSTD4). All collected populations were resistant to DDT and carbamates except for the ones in Matam (Northern region). Resistance to permethrin was uniformly detected in mosquitoes from all areas. Except for Barkédji and Touba, all populations were characterized by a susceptibility to 0.75% Permethrin. Susceptibility to type II pyrethroids was detected only in the Southern regions (Kédougou and Ziguinchor). All mosquito populations were susceptible to 5% Malathion, but only Kédougou and Matam mosquitoes were susceptible to 0.8% Malathion. All populations were resistant to 0.05% Pirimiphos-methyl, whereas those from Louga, Mbour and Barkédji, also exhibited resistance to 1% Fenitrothion. None of the known target site pyrethroid resistance mutations was present in the mosquito samples included in the genotyping analysis (performed in > 1500 samples). In contrast, a remarkably high (20-70-fold) overexpression of major detoxification genes wasobserved, suggesting that insecticide resistance is mostly mediated through metabolic mechanisms. These data provide important evidence to support dengue vector control in Senegal.

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The Interplay between Campylobacter and the Caecal Microbial Community of Commercial Broiler Chickens over Time

Microorganisms ◽

10.3390/microorganisms9020221 ◽

2021 ◽

Vol 9 (2) ◽

pp. 221

Author(s):

Ilaria Patuzzi ◽

Massimiliano Orsini ◽

Veronica Cibin ◽

Sara Petrin ◽

Eleonora Mastrorilli ◽

...

Keyword(s):

Campylobacter Jejuni ◽

Broiler Chickens ◽

Control Strategies ◽

Chicken Meat ◽

Control Measures ◽

Microbial Network ◽

Gut Colonization ◽

Commercial Broiler ◽

Zoonotic Bacteria ◽

Human Infections

Campylobacter is the most frequent foodborne zoonotic bacteria worldwide, with chicken meat being overwhelmingly the most important reservoir for human infections. Control measures implemented at the farm level (i.e., biosecurity or vaccination), which have been successfully applied to limit other pathogens, such as Salmonella, have not been effective in reducing Campylobacter occurrence. Thus, new approaches are needed to fully understand the ecological interactions of Campylobacter with host animals to effectively comprehend its epidemiology. The objective of this study was to analyse longitudinally the gut microbiota composition of Campylobacter-infected and non-infected farms to identify any difference that could potentially be indicative of gut colonization by Campylobacter spp. Differences in the colonization rate and timing were observed at the farms that became positive for Campylobacter jejuni over the investigated time points, even though in positive tests, the occurrence of Campylobacter jejuni gut colonization was not observed before the second week of the life of the birds. Significant differences were observed in the abundances of specific bacterial taxa between the microbiota of individuals belonging to farms that became Campylobacter positive during the study and those who remained negative with particular reference to Bacteroidales and Clostridiales, respectively. Moreover, Campylobacter colonization dramatically influenced the microbiota richness, although to a different extent depending on the infection timing. Finally, a key role of Faecalibacterium and Lactobacillus genera on the Campylobacter microbial network was observed. Understanding the ecology of the Campylobacter interaction with host microbiota during infection could support novel approaches for broiler microbial barrier restoration. Therefore, evidence obtained through this study can be used to identify options to reduce the incidence of infection at a primary production level based on the targeted influence of the intestinal microbiota, thus helping develop new control strategies in order to mitigate the risk of human exposure to Campylobacter by chicken meat consumption.

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High insecticide resistance mediated by different mechanisms in Culex quinquefasciatus populations from the city of Yaoundé, Cameroon

Scientific Reports ◽

10.1038/s41598-021-86850-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Abdou Talipouo ◽

Konstantinos Mavridis ◽

Elysée Nchoutpouen ◽

Borel Djiappi-Tchamen ◽

Emmanouil Alexandros Fotakis ◽

...

Keyword(s):

Insecticide Resistance ◽

Vector Control ◽

High Resistance ◽

Culex Quinquefasciatus ◽

Control Strategies ◽

Cuticular Hydrocarbon ◽

Control Measures ◽

High Frequencies ◽

The City ◽

Integrated Vector Control

AbstractCulex mosquitoes particularly Culex quinquefasciatus are important arboviral and filariasis vectors, however despite this important epidemiological role, there is still a paucity of data on their bionomics. The present study was undertaken to assess the insecticide resistance status of Cx. quinquefasciatus populations from four districts of Yaoundé (Cameroon). All Culex quinquefasciatus populations except one displayed high resistance to bendiocarb and malathion with mortalities ranging from 0 to 89% while high resistance intensity against both permethrin and deltamethrin was recorded. Molecular analyses revealed high frequencies of the ACE-1 G119S mutation (ranging from 0 to 33%) and kdr L1014F allele (ranging from 55 to 74%) in all Cx. quinquefasciatus populations. Significant overexpression was detected for cytochrome P450s genes CYP6AA7 and CYP6Z10, as well as for Esterase A and Esterase B genes. The total cuticular hydrocarbon content, a proxy of cuticular resistance, was significantly increased (compared to the S-lab strain) in one population. The study confirms strong insecticide resistance mediated by different mechanisms in Cx. quinquefasciatus populations from the city of Yaoundé. The expansion of insecticide resistance in Culex populations could affect the effectiveness of current vector control measures and stress the need for the implementation of integrated vector control strategies in urban settings.

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