Project description:The dengue virus (DENV) cause frequent epidemics infecting ~390 million people annually in over 100 countries. There are no approved vaccines or antiviral drugs for treatment of infected patients. However, there is a novel approach to control transmission of DENV by the mosquito vectors, Aedes aegypti and Ae. albopictus, using Wolbachia symbiont. The wMelPop strain of Wolbachia suppresses DENV transmission and shortens the mosquito life span. However, the underlying mechanism is poorly understood. To clarify this mechanism, either naïve Ae. albopictus (C6/36) or wMelPop-C6/36 cells were infected with DENV2. Analysis of host transcript profiles by RNAseq revealed that the presence of wMelPop had profound effects on mosquito host cell transcription in response to DENV2 infection. The viral RNA evolved from wMelPop-C6/36 contained low frequency mutations (~25%) within the coding region of transmembrane domain-1 (TMD1) of E protein. Mutations with >97 % frequencies were distributed within other regions of E, NS5 RNA-dependent RNA polymerase (NS5POL) domain, the TMDs of NS2A, NS2B, and NS4B. Moreover, while DENV2-infected naïve C6/36 cells showed syncytia formation, DENV2-infected wMelPop-C6/36 cells did not. The Wolbachia-induced mutant DENV2 can readily infect and replicate in naïve C6/36 cells; whereas, in the mutant DENV2- infected BHK-21 or Vero cells, the virus replication was delayed. In LLC-MK2 cells, the mutant failed to produce plaques. Additionally, in BHK-21 cells, many mutations in the viral genome reverted to WT and compensatory mutations in NS3 gene appeared. Our results suggest that wMelPop impacts significantly the interactions of DENV2 with mosquito and mammalian host cells.
Project description:Wolbachia, an endosymbiotic bacterium, is being investigated as a vector control agent in several insect species. Along with the well known classical reproductive parasitism Wolbachia employs against its host to spread within the population, it is emerging that the bacteria can protect the host against pathogens and reduced pathogen transmission. Anopheles mosquitoes, which transmit malaria, have never been found to harbour Wolbachia in nature, and despite numerous transinfection attempts, no stable line has been developed. However recently, two strains of Wolbachia, wAlbB from Aedes albopictus, and wRi from Drosophila simulans were cultured in Anopheles gambiae Sua5B cells. These cell lines provides an amenable system to study Wolbachia-Anopheles interaction in the absence of a stable transinfected line. It has been proposed that the compromised vector competence of Wolbachia infected insects is due to an up regulation of the basal immune state. We therefore completed a genome wide expression profile of Wolbachia infected Anopheles, assessing both wAlbB and wRi infected cells in parallel against uninfected Sua5B cells. Two strains of Wolbachia, wRi from Drosophila simulans and wAlbB from Aedes albopictus were transfered into Anopheles gambiae Sua5B cells via the shell vial technique. After over 30 passages, these Wolbachia infected cells lines were then compared, in parallel, to the original uninfected Sua5B cells using Affymetrix microarrays.
Project description:Certain strains of the intracellular endosymbiont Wolbachia can strongly inhibit or block the transmission of viruses such as dengue by Aedes mosquitoes, and the mechanisms responsible are still not well understood. Direct infusion and liquid chromatography FT-ICR mass spectrometry based lipidomicse DIMS and LCMS analyses were conducted using Aedes albopictus Aa23 cells that were infected with the wMel and wMelPop strains of Wolbachia compared to uninfected cells. Substantial shifts in the cellular lipid profile were apparent in the presence of Wolbachia. Most significantly, sphingolipids were depleted across all classes, and some reduction in diacylglyerol fatty acids and phosphatidylcholines was also observed. These lipid classes have previously been shown to be selectively enriched in DENV-infected mosquito cells, suggesting that Wolbachia may produce a cellular lipid environment that is antagonistic to viral replication. The data improve understanding of the intracellular interactions between Wolbachia and mosquitoes.
Project description:We characterized the miRNA composition of the nucleus and the cytoplasm of uninfected cells and compared it with the one of cells infected with the endosymbiotic bacterium Wolbachia strain wMelPop-CLA. We found an overall increase of small RNAs between 18 and 28 nucleotides in both cellular compartments in Wolbachia-infected cells and identified specific miRNAs induced and/or suppressed by the Wolbachia infection. We discuss the mechanisms that the cell may use to shuttle miRNAs between the cytoplasm and the nucleus. In addition, we identified piRNAs that changed their abundance in response to Wolbachia infection. The miRNAs and piRNAs identified in this study provide promising leads for investigations into the host-endosymbiont interactions and for better understanding of how Wolbachia manipulates the host miRNA machinery in order to facilitate its persistent replication in infected cells. Examination of small RNA profile in cytoplasmic and nuclear fractions of Aag 2 and Pop cells (Aedes aegypti)
Project description:Wolbachia is a vertically transmitted intracellular bacteria that infect most than 60% of insect species. The strains wMelPop and wMel were introduced in the dengue virus vector Aedes aegypti, naturally not infected by Wolbachia. Recently, it was shown that those two strains inhibit dengue virus replication into their new host, A. aegypti (Moreira et al. 2009 and Walker et al. in preparation). The aim of this project is to look at the transcriptional response of Aedes aegypti to infection with wMel and wMelPop and try to find some genes or pathway potentially involved in the viral interference.Four laboratory lines of A. aegypti were used throughout this study. The PGYP1 and Mel2 lines were generated by transinfection with wMelPop and wMel strains respectively. PGYP1.tet and Mel2tet lines were treated with the antibiotic tetracycline and cured from Wolbachia infection (McMeniman et al., 2009 and Walker et al in preparation). The Mosquitoes were reared under standard laboratory conditions (26 ± 2 °C, 12:12 light/dark cycle, 75% relative humidity). Mosquito larvae were fed 0.1mg/larvae of TetraMin Tropical Tablets once a day. Adults were transferred to cages (measuring 30 x 30 x 30 cm) at emergence at 400 individuals per cage. Adults were supplied with a basic diet of 10% sucrose solution (Turley et al., 2009).
Project description:Wolbachia, an endosymbiotic bacterium, is being investigated as a vector control agent in several insect species. Along with the well known classical reproductive parasitism Wolbachia employs against its host to spread within the population, it is emerging that the bacteria can protect the host against pathogens and reduced pathogen transmission. Anopheles mosquitoes, which transmit malaria, have never been found to harbour Wolbachia in nature, and despite numerous transinfection attempts, no stable line has been developed. However recently, two strains of Wolbachia, wAlbB from Aedes albopictus, and wRi from Drosophila simulans were cultured in Anopheles gambiae Sua5B cells. These cell lines provides an amenable system to study Wolbachia-Anopheles interaction in the absence of a stable transinfected line. It has been proposed that the compromised vector competence of Wolbachia infected insects is due to an up regulation of the basal immune state. We therefore completed a genome wide expression profile of Wolbachia infected Anopheles, assessing both wAlbB and wRi infected cells in parallel against uninfected Sua5B cells.
Project description:Whole genome transcriptional profiling comparing Ae. aegypti infected with Wolbachia sp. wMelPop (PGYP1) to an uninfected Ae. aegypti control line (PGYP1.tet). The objective of the experiment was to identify genes that may be involved in the life shortening phenotype associated with wMelPop infection.
Project description:We characterized the miRNA composition of the nucleus and the cytoplasm of uninfected cells and compared it with the one of cells infected with the endosymbiotic bacterium Wolbachia strain wMelPop-CLA. We found an overall increase of small RNAs between 18 and 28 nucleotides in both cellular compartments in Wolbachia-infected cells and identified specific miRNAs induced and/or suppressed by the Wolbachia infection. We discuss the mechanisms that the cell may use to shuttle miRNAs between the cytoplasm and the nucleus. In addition, we identified piRNAs that changed their abundance in response to Wolbachia infection. The miRNAs and piRNAs identified in this study provide promising leads for investigations into the host-endosymbiont interactions and for better understanding of how Wolbachia manipulates the host miRNA machinery in order to facilitate its persistent replication in infected cells.