Abstract
The mosquito Aedes aegypti (L.) is vector of several arboviruses including dengue, yellow fever, chikungunya, and more recently zika. Previous transcriptomic studies have been performed to elucidate altered pathways in response to viral infection. However, the intrinsic coupling between alimentation and infection were unappreciated in these studies. Feeding is required for the initial mosquito contact with the virus and these events are highly dependent. Addressing this relationship, we reinterrogated datasets of virus-infected mosquitoes with two different diet schemes (fed and unfed mosquitoes), evaluating the metabolic cross-talk during both processes. We constructed coexpression networks with the differentially expressed genes of these comparison: virus-infected versus blood-fed mosquitoes and virus-infected versus unfed mosquitoes. Our analysis identified one module with 110 genes that correlated with infection status (representing ~0.7% of the A. aegypti genome). Furthermore, we performed a machine-learning approach and summarized the infection status using only four genes (AAEL012128, AAEL014210, AAEL002477, and AAEL005350). While three of the four genes were annotated as hypothetical proteins, AAEL012128 gene is a membrane amino acid transporter correlated with viral envelope binding. This gene alone is able to discriminate all infected samples and thus should have a key role to discriminate viral infection in the A. aegypti mosquito. Moreover, validation using external datasets found this gene as differentially expressed in four transcriptomic experiments. Therefore, these genes may serve as a proxy of viral infection in the mosquito and the others 106 identified genes provides a framework to future studies.
Highlights
The mosquito Aedes aegypti (L.) is the main vector of dengue virus (DENV), West Nile virus (WNV), and Yellow fever virus (YFV), present worldwide (Mackenzie et al, 2004; Lorenzo et al, 2014); more than 2.5 billion people in over 100 countries are at risk of contracting dengue alone (World Health Organization, 2015), while yellow fever remains endemic in tropical regions of Africa and South America (Bae et al, 2005)
After we identified the global differences between the expression profiles in infected groups (DENV, YFV, and WNV) in comparison with feeding status (BF and N-BF), we performed Principal Component Analysis (PCA) to verify whether these significant differentially expressed genes (DEGs) could discriminate infected, uninfected and N-BF mosquitoes (Figure 3)
In order to independently validate the role of AAEL012128, gene identified as summarizing the infection status in our combined study, we identified two datasets related to DENV infection and verified the expression of this gene
Summary
The mosquito Aedes aegypti (L.) is the main vector of dengue virus (DENV), West Nile virus (WNV), and Yellow fever virus (YFV), present worldwide (Mackenzie et al, 2004; Lorenzo et al, 2014); more than 2.5 billion people in over 100 countries are at risk of contracting dengue alone (World Health Organization, 2015), while yellow fever remains endemic in tropical regions of Africa and South America (Bae et al, 2005). In 2007, the A. aegypti complete genome was released (Nene et al, 2007) and vector-specific databases were developed, such as Vector Base (Giraldo-Calderon et al, 2015). This allowed expression assays addressing viral infection (Colpitts et al, 2011), enabling new insights about the A. aegypti gene regulation and transcriptional processes (Dissanayake et al, 2010; Colpitts et al, 2011). Female mosquitoes acquire blood that is necessary for egg development and may subsequently become infected with pathogens Both infection and blood feeding processes induce changes in gene expression levels. The intrinsic physiological crosstalk between these process are linked and a joint analysis is required to assess patterns of infection possibly unappreciated in previous studies, due to the difficulty of separating the gene expression patterns that arise from feeding on blood from that resultant of the infection process due to host–pathogen interactions
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