Transcriptional response of Wolbachia-transinfected Aedes aegypti mosquito cells to dengue virus at early stages of infection

Abstract

Mosquito-borne flaviviruses are responsible for viral infections and represent a considerable public health burden. Aedes aegypti is the principal vector of dengue virus (DENV), therefore understanding the intrinsic virus-host interactions is vital, particularly in the presence of the endosymbiont Wolbachia, which blocks virus replication in mosquitoes. Here, we examined the transcriptional response of Wolbachia-transinfected Ae. aegypti Aag2 cells to DENV infection. We identified differentially expressed immune genes that play a key role in the activation of anti-viral defence such as the Toll and immune deficiency pathways. Further, genes encoding cytosine and N⁶-adenosine methyltransferases and SUMOylation, involved in post-transcriptional modifications, an antioxidant enzyme, and heat-shock response were up-regulated at the early stages of DENV infection and are reported here for the first time. Additionally, several long non-coding RNAs were among the differentially regulated genes. Our results provide insight into Wolbachia-transinfected Ae. aegypti's initial virus recognition and transcriptional response to DENV infection.

Keywords: Aedes aegypti; Wolbachia; dengue virus; differential gene expression; transcriptome.

Fig. 1.

Differentially expressed protein-coding genes (DEGs) and long non-coding RNAs (lncRNAs) in response to DENV infection in Wolbachia -transinfected Aag2 cells. The bars represent the number of (a) DEGs and (b) lncRNAs identified using a fold-change of ≥2.0 and an adjusted P value of <0.05. The up-regulated DEGs and lncRNAs are shown in blue and the down-regulated DEGs and lncRNAs are shown in red. (c) Venn diagram showing DEGs in DENV-infected versus uninfected Wolbachia -transinfected Aag2 cells. A total of 453 overlapping DEGs at more than one time point were found. Each coloured circle represents a sample collection time point.

Fig. 2.

RT-qPCR validation of the differentially expressed genes (DEGs). The bar graphs represent the RNA-Seq normalized gene reads as counts per million and RT-qPCR relative expression results of the DEGs in DENV-infected Wolbachia -transinfected Aag2 cells at time points 1, 6, and 24 hpi. The error bars represent mean normalized expression (MNE) from the three biological replicates.

Fig. 3.

Gene Ontology (GO) analysis of differentially expressed genes (DEGs) in response to DENV infection in Wolbachia -transinfected Aag2 cells. The bar graphs represent the top 20 most abundant gene ontology terms for each category of biological process, molecular function, and cellular components at time points 1, 6, and 24 hpi. The x-axis shows the fold change enrichment and significance of each GO term, and the y-axis the GO term category names.