Comparative Susceptibility of Mosquito Populations in North Queensland, Australia to Oral Infection with Dengue Virus

Dengue fever is the most common arboviral disease worldwide. It is caused by dengue viruses (DENV) and the mosquito Aedes aegypti is its primary vector. One of the most powerful determinants of a mosquito's ability to transmit DENV is the length of the extrinsic incubation period (EIP), the time it takes for a virus to be transmitted by a mosquito after consuming an infected blood meal. Here, we repeatedly measured DENV load in the saliva of individual mosquitoes over their lifetime and used this in combination with a breeding design to determine the extent to which EIP might respond to the evolutionary forces of drift and selection. We demonstrated that genetic variation among mosquitoes contributes significantly to transmission potential and length of EIP. We reveal that shorter EIP is genetically correlated with reduced mosquito lifespan, highlighting negative life-history consequences for virus-infected mosquitoes. This work highlights the capacity for local genetic variation in mosquito populations to evolve and to dramatically affect the nature of human outbreaks. It also provides the impetus for isolating mosquito genes that determine EIP. More broadly, our dual experimental approach offers new opportunities for studying the evolutionary potential of transmission traits in other vector/pathogen systems.

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“…; Ye et al. ). Viral load is expressed as DENV copy number per tissue using absolute quantification.…”

Section: Methodsmentioning

confidence: 98%

Evolutionary potential of the extrinsic incubation period of dengue virus inAedes aegypti

Chenoweth

Carrasco

et al. 2016

Evolution

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“…This strain was selected because it caused one of the largest dengue outbreaks in Australia [43] and because it has been demonstrated to infect both w Mel and Wildtype mosquitoes at a high rate [44]. Passage 6 of DENV 3 (PFU 10 6 ) was propagated using the protocol by Ye et al ., [45] and stored in single use aliquots of 1mL at -80°C. The virus was mixed with defibrinated sheep’s blood in the ratio 1:1 and fed through a membrane feeder to three to five day old mosquitoes.…”

Section: Methodsmentioning

confidence: 99%

Wolbachia-Based Dengue Virus Inhibition Is Not Tissue-Specific in Aedes aegypti

Amuzu

McGraw

2016

PLoS Negl Trop Dis

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BackgroundDengue fever, caused by the dengue virus (DENV), is now the most common arbovirus transmitted disease globally. One novel approach to control DENV is to use the endosymbiotic bacterium, Wolbachia pipientis, to limit DENV replication inside the primary mosquito vector, Aedes aegypti. Wolbachia that is naturally present in a range of insects reduces the capacity for viruses, bacteria, parasites and fungi to replicate inside insects. Wolbachia’s mode of action is not well understood but may involve components of immune activation or competition with pathogens for limited host resources. The strength of Wolbachia-based anti DENV effects appear to correlate with bacterial density in the whole insect and in cell culture. Here we aimed to determine whether particular tissues, especially those with high Wolbachia densities or immune activity, play a greater role in mediating the anti DENV effect.Methodology/findingsAe. aegypti mosquito lines with and without Wolbachia (Wildtype) were orally fed DENV 3 and their viral loads subsequently measured over two time points post infection in the midgut, head, salivary glands, Malpighian tubules, fat body and carcass. We did not find correlations between Wolbachia densities and DENV loads in any tissue, nor with DENV loads in salivary glands, the endpoint of infection. This is in contrast with strong positive correlations between DENV loads in a range of tissues and salivary gland loads for Wildtype mosquitoes. Lastly, there was no evidence of a heightened role for tissues with known immune function including the fat body and the Malpighian tubules in Wolbachia’s limitation of DENV.Conclusion/significanceWe conclude that the efficacy of DENV blocking in Wolbachia infected mosquitoes is not reliant on any particular tissue. This work therefore suggests that the mechanism of Wolbachia-based antiviral effects is either systemic or acts locally via processes that are fundamental to diverse cell types. We further conclude that the relationship between DENV blocking and Wolbachia density is not linear in mosquito tissues

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“…Thus, the events occurring during the first 3–4 days post-infected blood meal are critical to determining whether a given female becomes competent to transmit virus in a future blood meal. However, evidence does exist indicating that successful virus replication in the midgut and subsequent dissemination to other tissues including the salivary glands and saliva is dependent to some extent on virus titer in the initial blood meal [35,86,87,88]. Thus, virus dissemination to low titers, as evidenced by assessment of leg or head tissues, may not result in successful dissemination to salivary glands and saliva.…”

Section: A Aegypti and Denv Interaction Post-blood Feeding On Infmentioning

confidence: 99%

Genome Investigations of Vector Competence in Aedes aegypti to Inform Novel Arbovirus Disease Control Approaches

Severson

Behura

2016

Insects

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Dengue (DENV), yellow fever, chikungunya, and Zika virus transmission to humans by a mosquito host is confounded by both intrinsic and extrinsic variables. Besides virulence factors of the individual arboviruses, likelihood of virus transmission is subject to variability in the genome of the primary mosquito vector, Aedes aegypti. The “vectorial capacity” of A. aegypti varies depending upon its density, biting rate, and survival rate, as well as its intrinsic ability to acquire, host and transmit a given arbovirus. This intrinsic ability is known as “vector competence”. Based on whole transcriptome analysis, several genes and pathways have been predicated to have an association with a susceptible or refractory response in A. aegypti to DENV infection. However, the functional genomics of vector competence of A. aegypti is not well understood, primarily due to lack of integrative approaches in genomic or transcriptomic studies. In this review, we focus on the present status of genomics studies of DENV vector competence in A. aegypti as limited information is available relative to the other arboviruses. We propose future areas of research needed to facilitate the integration of vector and virus genomics and environmental factors to work towards better understanding of vector competence and vectorial capacity in natural conditions.

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Comparative Susceptibility of Mosquito Populations in North Queensland, Australia to Oral Infection with Dengue Virus

Cited by 33 publications

References 40 publications

Evolutionary potential of the extrinsic incubation period of dengue virus inAedes aegypti

Evolutionary potential of the extrinsic incubation period of dengue virus inAedes aegypti

Wolbachia-Based Dengue Virus Inhibition Is Not Tissue-Specific in Aedes aegypti

Genome Investigations of Vector Competence in Aedes aegypti to Inform Novel Arbovirus Disease Control Approaches

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