Aedes aegypti, better known as the yellow fever mosquito, is also the primary vector of Dengue virus, an important (re-)emerging pathogen that infects tens of millions of people in tropical areas of the world. The yellow fever mosquito shares with its distant relative, the malaria mosquito Anopheles gambiae, a strong preference for blood feeding on humans. As Dengue virus is primarily transmitted from human to mosquito to human, Ae. aegypi’s preference for human hosts is largely responsible for its importance as a vector of Dengue.
It is well established that Ae. aegypti host preference is largely regulated by its olfactory system. In addition, Ae. aegypti females only host seek during certain phases of their life cycle. For example, the response of female Ae. aegyti to hosts ceases for about 96 hours following a blood meal. We are currently examining if miRNAs are involved in regulating the olfactory system’s response to host-seeking.
As a first step in this study, we are characterizing the transcriptome of Ae. aegypti antennae prior to blood feeding, as well as 3, 24, 48 and 72 hours post blood feeding. We expect that the transcription or translation of genes involved in host seeking will be significantly reduced following blood feeding. We are primarily focussing on several gene families: the Odorant Binding Proteins, the Olfaction Receptors, and Ionotrophic Receptors. We are currently analyzing RNAseq data for three biological replicates for each of the five time points included in the study. This analyses required the dissection of the antennae of approximately 12,000 female Ae. aegypti. This data is currently being prepared for publication.
We are also examining the expression profiles of miRNAs in the same time points using a RNAseq approach. Our hypothesis is that miRNAs that play a role in suppressing the translation of olfaction gene mRNAs into proteins, will be up-regulated following host seeking. We have already identified a substantial number of previously unknown Ae. aegypti miRNAs expressed in Ae. aegypti antennae, and are in the process of completing the biological replicates. This is no trivial matter, as our miRNA analyses requires the dissection of the antennae of some 40,000 female Ae. aegypti.
Following bioinformatic analyses to identify miRNAs and their targets, the impact of candidate miRNAs on olfaction genes will be examined using an in vitro assay.
Partial funding for this work is provide by a Texas AgriLife Research Genomics and Bioinformatics Seed Grant