scholarly journals High temperature cycles result in maternal transmission and dengue infection differences between Wolbachia strains in Aedes aegypti

2020 ◽  
Author(s):  
Maria Vittoria Mancini ◽  
Thomas H. Ant ◽  
Christie S. Herd ◽  
Daniel D. Gingell ◽  
Shivan M. Murdochy ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Aedes Aegypti ◽  
Virus Transmission ◽  
Temperature Cycle ◽  
Larval Rearing ◽  
Mosquito Vector ◽  
Maternal Transmission ◽  
Rearing Temperature ◽  
Dengue Control ◽  
The Impact

AbstractEnvironmental factors play a crucial role in the population dynamics of arthropod endosymbionts, and therefore in the deployment of Wolbachia symbionts for the control of dengue arboviruses. The potential of Wolbachia to invade, persist and block virus transmission depends in part on its intracellular density. Several recent studies have highlighted the importance of larval rearing temperature in modulating Wolbachia densities in adults, suggesting that elevated temperatures can severely impact some strains, while having little effect on others. The effect of a replicated tropical heat cycle on Wolbachia density and levels of virus blocking was assessed using Aedes aegypti lines carrying strains wMel and wAlbB, two Wolbachia strains currently used for dengue control. Impacts on intracellular density, maternal transmission fidelity and dengue inhibition capacity were observed for wMel. In contrast wAlbB-carrying Ae. aegypti maintained a relatively constant intracellular density at high temperatures and conserved its capacity to inhibit dengue. Following larval heat treatment, wMel showed a degree of density recovery in aging adults, although this was compromised by elevated air temperatures. When choosing the Wolbachia strain to be used in a dengue control programme it is important to consider the effects of environmental temperatures on invasiveness and virus inhibition.Author summaryIn the past decades, dengue incidence has dramatically increased all over the world. An emerging dengue control strategy utilizes Ae. aegypti mosquitoes artificially transinfected with the bacterial symbiont Wolbachia, with the ultimate aim of replacing wild mosquito populations. Wolbachia is transmitted from mother to offspring and is able to interfere with virus transmission within the mosquito vector. However, the rearing temperature of mosquito larvae is known to impact on some Wolbachia strains. In this study, we compared the effects of a temperature cycle mimicking natural breeding sites in tropical climates on two Wolbachia strains, currently used for open field trials. We observed that the strain wMel was susceptible to high larval rearing temperatures, while the strain wAlbB resulted to be more stable. These results underlines the importance of understanding the impact of environmental factors on released mosquitoes, in order to ensure the most efficient strategy for dengue control.

scholarly journals Establishment of Wolbachia strain wAlbB in Malaysian populations of Aedes aegypti for dengue control

2019 ◽  
Author(s):  
W. A. Nazni ◽  
A. A. Hoffmann ◽  
A. Noor Afizah ◽  
Y. L. Cheong ◽  
M. V. Mancini ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Virus Transmission ◽  
Larval Rearing ◽  
Kuala Lumpur ◽  
Novel Approach ◽  
Dengue Transmission ◽  
Vector Mosquito ◽  
Primary Vector ◽  
Dengue Control ◽  
Very High

AbstractDengue has enormous health impacts globally. A novel approach to decrease dengue incidence involves the introduction of Wolbachia endosymbionts that block dengue virus transmission into populations of the primary vector mosquito, Aedes aegypti. The wMel Wolbachia strain has previously been trialed in open releases of Ae. aegypti; however the wAlbB strain has been shown to maintain higher density than wMel at high larval rearing temperatures. Releases of Ae. aegypti mosquitoes carrying wAlbB were carried out in 6 diverse sites in greater Kuala Lumpur, Malaysia, with high endemic dengue transmission. The strain was successfully established and maintained at very high population frequency at some sites, or persisted with additional releases following fluctuations at other sites. Based on passive case monitoring, reduced human dengue incidence was observed in the release sites when compared to control sites. The wAlbB strain of Wolbachia provides a promising option as a tool for dengue control, particularly in very hot climates.

scholarly journals Sequential Infection of Aedes aegypti Mosquitoes with Chikungunya Virus and Zika Virus Enhances Early Zika Virus Transmission

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 177 ◽  
Author(s):  
Tereza Magalhaes ◽  
Alexis Robison ◽  
Michael Young ◽  
William Black ◽  
Brian Foy ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Blood Meal ◽  
Zika Virus ◽  
Chikungunya Virus ◽  
Vector Competence ◽  
Virus Transmission ◽  
Mosquito Vector ◽  
Molecular Aspects ◽  
Virus Interactions ◽  
Sequential Infection

In urban settings, chikungunya, Zika, and dengue viruses are transmitted by Aedes aegypti mosquitoes. Since these viruses co-circulate in several regions, coinfection in humans and vectors may occur, and human coinfections have been frequently reported. Yet, little is known about the molecular aspects of virus interactions within hosts and how they contribute to arbovirus transmission dynamics. We have previously shown that Aedes aegypti exposed to chikungunya and Zika viruses in the same blood meal can become coinfected and transmit both viruses simultaneously. However, mosquitoes may also become coinfected by multiple, sequential feeds on single infected hosts. Therefore, we tested whether sequential infection with chikungunya and Zika viruses impacts mosquito vector competence. We exposed Ae. aegypti mosquitoes first to one virus and 7 days later to the other virus and compared infection, dissemination, and transmission rates between sequentially and single infected groups. We found that coinfection rates were high after sequential exposure and that mosquitoes were able to co-transmit both viruses. Surprisingly, chikungunya virus coinfection enhanced Zika virus transmission 7 days after the second blood meal. Our data demonstrate heterologous arbovirus synergism within mosquitoes, by unknown mechanisms, leading to enhancement of transmission under certain conditions.

scholarly journals Laboratory colonization by Dirofilaria immitis alters the microbiome of female Aedes aegypti mosquitoes

2020 ◽  
Author(s):  
Abdulsalam Adegoke ◽  
Erik Neff ◽  
Amie Geary ◽  
Montana Ciara Husser ◽  
Kevin Wilson ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Dirofilaria Immitis ◽  
Mosquito Species ◽  
Bacterial Species ◽  
Klebsiella Oxytoca ◽  
Variable Region ◽  
Blood Feeding ◽  
Mosquito Vector ◽  
Filarial Nematodes ◽  
The Impact

Abstract Background: The ability of blood feeding arthropods to successfully acquire and transmit pathogens of medical and veterinary importance has been shown to be interfered with, or enhanced by, the arthropod’s native microbiome. Mosquitoes transmit viruses, protozoan and filarial nematodes, the majority of which contribute to the 17% of infectious disease cases worldwide. Dirofilaria immitis , a mosquito transmitted by filarial nematodes of dogs and cats, is vectored by several mosquito species including Aedes aegypti . Methods: In this study, we investigated the impact of D. immitis colonization on the microbiome of laboratory reared female A. aegypti . Metagenomic analysis of the V3-V4 variable region of the microbial 16SRNA was used for identification of the microbial differences down to species level. Results We generated a total of 1068 OTUs representing 16 phyla, 181 genera and 271 bacterial species. Overall, in order of abundance, Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes were the most represented phylum with D. immitis infected mosquitoes having more of Proteobacteria (71%) than uninfected mosquitoes (56.9%). An interesting finding in this study is the detection of Klebsiella oxytoca in relatively similar abundance in infected and uninfected mosquitoes, suggesting a possible endosymbiotic relationship, and has been previously shown to indirectly compete for nutrients with fungi on domestic housefly eggs and larva. While D. immitis colonization has no effect on the overall species richness, we identified significant differences in the composition of selected bacteria genus and phylum between the two groups. We also reported distinct compositional and phylogenetic differences in the individual bacteria species when commonly identified bacteria were compared. Conclusions In conclusion, this is the first study to the best of our knowledge to understand the impact of a filarial infection on the microbiome of its mosquito vector. Further studies are required to identify bacteria species that could play an important role in the mosquito biology. While the microbiome composition of A. aegypti mosquito have been previously reported, our study shows that in an effort to establish itself, a filarial nematode modifies and alters the overall microbial diversity within its mosquito host.

scholarly journals Transcriptomic analysis and molecular docking reveal genes involved in the response of Aedes aegypti larvae to an essential oil extracted from Eucalyptus

2021 ◽  
Vol 15 (7) ◽  
pp. e0009587
Author(s):  
Ivana Sierra ◽  
Jose Manuel Latorre-Estivalis ◽  
Lucila Traverso ◽  
Paula V. Gonzalez ◽  
Ariel Aptekmann ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Essential Oil ◽  
Aedes Aegypti ◽  
Vector Control ◽  
Gene Families ◽  
Control Group ◽  
Mosquito Vector ◽  
Rna Seq ◽  
Chemosensory Proteins ◽  
The Impact

Background Aedes aegypti (L.) is an urban mosquito, vector of several arboviruses that cause severe diseases in hundreds of million people each year. The resistance to synthetic insecticides developed by Ae. aegypti populations worldwide has contributed to failures in vector control campaigns, increasing the impact of arbovirus diseases. In this context, plant-derived essential oils with larvicidal activity could be an attractive alternative for vector control. However, the mode of action and the detoxificant response of mosquitoes to plant derived compounds have not been established, impairing the optimization of their use. Methods and findings Here we compare gene expression in Ae. aegypti larvae after 14 hrs of exposure to Eucalyptus camaldulensis essential oil with a control group exposed to vehicle (acetone) for the same lapse, by using RNA-Seq. We found differentially expressed genes encoding for cuticle proteins, fatty-acid synthesis, membrane transporters and detoxificant related gene families (i.e. heat shock proteins, cytochromes P450, glutathione transferases, UDP-glycosyltransferases and ABC transporters). Finally, our RNA-Seq and molecular docking results provide evidence pointing to a central involvement of chemosensory proteins in the detoxificant response in mosquitoes. Conclusions and significance Our work contributes to the understanding of the physiological response of Ae. aegypti larvae to an intoxication with a natural toxic distilled from Eucalyptus leafs. The results suggest an involvement of most of the gene families associated to detoxification of xenobiotics in insects. Noteworthy, this work provides important information regarding the implication of chemosensory proteins in the detoxification of a natural larvicide. Understanding the mode of detoxification of Eucalyptus distilled compounds could contribute to their implementation as a tool in mosquito control.

scholarly journals Laboratory colonization by Dirofilaria immitis alters the microbiome of female Aedes aegypti mosquitoes

2020 ◽  
Author(s):  
Abdulsalam Adegoke ◽  
Erik Neff ◽  
Amie Geary ◽  
Montana Ciara Husser ◽  
Kevin Wilson ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Dirofilaria Immitis ◽  
Mosquito Species ◽  
Bacterial Species ◽  
Klebsiella Oxytoca ◽  
Variable Region ◽  
Blood Feeding ◽  
Mosquito Vector ◽  
Filarial Nematodes ◽  
The Impact

Abstract Background: The ability of blood-feeding arthropods to successfully acquire and transmit pathogens of medical and veterinary importance has been shown to be interfered with, or enhanced by, the arthropod’s native microbiome. Mosquitoes transmit viruses, protozoan and filarial nematodes, the majority of which contribute to the 17% of infectious disease cases worldwide. Dirofilaria immitis, a mosquito-transmitted filarial nematodes of dogs and cats, is vectored by several mosquito species including Aedes aegypti.Methods: In this study, we investigated the impact of D. immitis colonization on the microbiome of laboratory reared female Ae. aegypti. Metagenomic analysis of the V3-V4 variable region of the microbial 16S RNA gene was used for identification of the microbial differences down to species level.Results: We generated a total of 1068 OTUs representing 16 phyla, 181 genera and 271 bacterial species. Overall, in order of abundance, Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes were the most represented phylum with D. immitis-infected mosquitoes having more of Proteobacteria (71%) than uninfected mosquitoes (56.9%). An interesting finding in this study is the detection of Klebsiella oxytoca in relatively similar abundance in infected and uninfected mosquitoes, suggesting a possible endosymbiotic relationship, and has been previously shown to indirectly compete for nutrients with fungi on domestic housefly eggs and larvae. While D. immitis colonization has no effect on the overall species richness, we identified significant differences in the composition of selected bacterial genera and phyla between the two groups. We also reported distinct compositional and phylogenetic differences in the individual bacterial species when commonly identified bacteria were compared.Conclusions: In conclusion, this is the first study to the best of our knowledge, this is the first study to understand the impact of a filarial infection on the microbiome of its mosquito vector. Further studies are required to identify bacteria species that could play an important role in the mosquito biology. While the microbiome composition of Ae. aegypti mosquito have been previously reported, our study shows that in an effort to establish itself, a filarial nematode modifies and alters the overall microbial diversity within its mosquito host.

Dengue and the introduction of mosquito-transmitted viruses into Australia

2016 ◽  
Vol 37 (4) ◽  
pp. 167
Author(s):  
Andrew F van den Hurk
Keyword(s):  
Aedes Aegypti ◽  
Dengue Virus ◽  
Virus Transmission ◽  
Current Situation ◽  
Mosquito Vector ◽  
And Control

Dengue virus outbreaks involving 100s of cases periodically occur in north Queensland, the area of Australia where the primary mosquito vector, Aedes aegypti, occurs. This article summarises the ecology, history, current situation and control of dengue virus transmission in Australia and examines the threat posed by newly emergent arboviruses, such as Zika and chikungunya viruses.

scholarly journals Voltage-sensitive sodium channel (Vssc) mutations associated with pyrethroid insecticide resistance in Aedes aegypti (L.) from Jeddah, Kingdom of Saudi Arabia - baseline information for a Wolbachia release program

2021 ◽  
Author(s):  
Nancy M Endersby-Harshman ◽  
AboElgasim Ali ◽  
Basim Alhumrani ◽  
Mohammed Abdullah Alkuriji ◽  
Mohammed B. Al- Fageeh ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Aedes Aegypti ◽  
Insecticide Resistance ◽  
Sodium Channel ◽  
Dominant Role ◽  
Public Health Problem ◽  
Type I ◽  
Mosquito Vector ◽  
Genotype Frequencies ◽  
The Impact

Background: Dengue suppression often relies on control of the mosquito vector, Aedes aegypti, through applications of insecticides of which the pyrethroid group has played a dominant role. Insecticide resistance is prevalent in Ae. aegypti around the world and the resulting reduction of insecticide efficacy is likely to exacerbate the impact of dengue. Dengue has been a public health problem in Saudi Arabia, particularly in Jeddah, since its discovery there in the 1990s and insecticide use for vector control is widespread throughout the city. An alternative approach to insecticide use, based on blocking dengue transmission in mosquitoes by the endosymbiont Wolbachia, is being trialled in Jeddah following the success of this approach in Australia and Malaysia. Knowledge of insecticide resistance status of mosquito populations in Jeddah is a prerequisite for establishing a Wolbachia-based dengue control program as releases of Wolbachia mosquitoes succeed when resistance status of the release population is similar to that of the wild population. Methods: WHO resistance bioassays of mosquitoes with deltamethrin, permethrin and DDT were used in conjunction with TaqMan® SNP Genotyping Assays to characterise mutation profiles of Ae. aegypti from Jeddah. Results: Screening of the voltage sensitive sodium channel (Vssc), the pyrethroid target-site, revealed mutations at codons 989, 1016 and 1534 in Ae. aegypti from two districts of Jeddah. The triple mutant homozygote (1016G/1534C/989P) was confirmed from Al Safa and Al Rawabi. Bioassays with pyrethroids (Type I and II) and DDT showed that mosquitoes were resistant to each of these compounds based on WHO definitions. An association between Vssc mutations and resistance was established for the Type II pyrethroid, deltamethrin, with one genotype (989P/1016G/1534F) conferring a survival advantage over two others (989S/1016V/1534C and the triple heterozygote). An indication of synergism of Type I pyrethroid activity with piperonyl butoxide suggests that detoxification by cytochrome P450s accounts for some of the pyrethroid resistance response in Ae. aegypti populations from Jeddah. Conclusions: The results provide a baseline for monitoring and management of resistance as well as knowledge of Vssc genotype frequencies required in Wolbachia release populations to ensure homogeneity with the target field population.

scholarly journals Environmental Factors Contribute to the Transmissibility of COVID-19: Evidence from an Improved SEIR Model

2021 ◽  
Author(s):  
Jie Li ◽  
Kun Jia ◽  
Wenwu Zhao ◽  
Bo Yuan ◽  
Yanxu Liu
Keyword(s):  
Environmental Factors ◽  
Pearson Correlation ◽  
Time Lag ◽  
Virus Transmission ◽  
Ecological Factors ◽  
Population Mobility ◽  
Seir Model ◽  
Factors Affecting ◽  
Distributed Lag ◽  
The Impact

Abstract COVID-19 is ravaging Brazil, and its spread shows spatial heterogeneity. Changes in the environment have been implicated as potential factors involved in COVID-19 transmission. However, considerable research efforts have not elucidated the risk of environmental factors on COVID-19 transmission from the perspective of infectious disease dynamics. The aim of this study is to model the influence of the environment on COVID-19 transmission and to analyze how the socio-ecological factors affecting the probability of virus transmission in 10 states dramatically shifted during the early stages of the epidemic in Brazil. First, this study used a Pearson correlation to analyze the interconnection between COVID-19 morbidity and socio-ecological factors, and identified factors with significant correlations as the dominant factors affecting COVID-19 transmission. Then, the time-lag effect of dominant factors on the morbidity of COVID-19 was investigated by constructing a distributed lag nonlinear model, and the results were considered to be an improvement over the SEIR model. Lastly, a machine learning method was introduced to explore the nonlinear relationship between the environmental propagation probability and socio-ecological factors. By analyzing the impact of environmental factors on virus transmission, it can be found that population mobility directly caused by human activities had a greater impact on virus transmission than temperature and humidity. The heterogeneity of meteorological factors can be accounted for by the diverse climate patterns in Brazil. The improved SEIR model was adopted to explore the interconnection of COVID-19 transmission and the environment, which revealed a new strategy to probe the causal links between them.

scholarly journals Detecting the impact of temperature on transmission of Zika, dengue and chikungunya using mechanistic models

2016 ◽  
Author(s):  
Erin A. Mordecai ◽  
Jeremy M. Cohen ◽  
Michelle V. Evans ◽  
Prithvi Gudapati ◽  
Leah R. Johnson ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Mechanistic Model ◽  
The United States ◽  
Human Case ◽  
Mosquito Vector ◽  
Temperature Dependent ◽  
Model Predictions ◽  
Incidence Risk ◽  
The Impact ◽  
Case Data

AbstractRecent epidemics of Zika, dengue, and chikungunya have heightened the need to understand the seasonal and geographic range of transmission by Aedes aegypti and Ae. albopictus mosquitoes. We use mechanistic transmission models to derive predictions for how the probability and magnitude of transmission for Zika, chikungunya, and dengue change with mean temperature, and we show that these predictions are well matched by human case data. Across all three viruses, models and human case data both show that transmission occurs between 18-34°C with maximal transmission occurring in a range from 26-29°C. Controlling for population size and two socioeconomic factors, temperature-dependent transmission based on our mechanistic model is an important predictor of human transmission occurrence and incidence. Risk maps indicate that tropical and subtropical regions are suitable for extended seasonal or year-round transmission, but transmission in temperate areas is limited to at most three months per year even if vectors are present. Such brief transmission windows limit the likelihood of major epidemics following disease introduction in temperate zones.Author SummaryUnderstanding the drivers of recent Zika, dengue, and chikungunya epidemics is a major public health priority. Temperature may play an important role because it affects mosquito transmission, affecting mosquito development, survival, reproduction, and biting rates as well as the rate at which they acquire and transmit viruses. Here, we measure the impact of temperature on transmission by two of the most common mosquito vector species for these viruses, Aedes aegypti and Ae. albopictus. We integrate data from several laboratory experiments into a mathematical model of temperature-dependent transmission, and find that transmission peaks at 26-29°C and can occur between 18-34°C. Statistically comparing model predictions with recent observed human cases of dengue, chikungunya, and Zika across the Americas suggests an important role for temperature, and supports model predictions. Using the model, we predict that most of the tropics and subtropics are suitable for transmission in many or all months of the year, but that temperate areas like most of the United States are only suitable for transmission for a few months during the summer (even if the mosquito vector is present).

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