Parry, R. | bioRxiv Science

bioRxiv2018

Density dependent enhancement effect of Wolbachia and the host RNAi response to a densovirus in Aedes cells

The endosymbiotic bacterium Wolbachia pipientis has been shown to restrict a range of RNA viruses in Drosophila melanogaster and transinfected dengue mosquito, Aedes aegypti. Here, we show that Wolbachia infection enhances replication of Aedes albopictus densovirus (AalDNV-1), a single stranded DNA virus, in Aedes cell lines in a density-dependent manner. Analysis of previously produced small RNAs of Aag2 cells showed that Wolbachia-infected cells produced greater proportions of viral derived short interfering RNAs as compared to uninfected cells. Additionally, we found production of viral derived PIWI-like RNAs (vpiRNA) produced in response to AalDNV-1 infection. Nuclear fractions of Aag2 cells produced a primary vpiRNA signature U1 bias whereas the typical \"ping-pong\" signature (U1 - A10) was evident in the cytoplasmic fraction. This is the first report of the density-dependent enhancement of DNA viruses by Wolbachia. Further, we report the generation of vpiRNAs in a DNA virus-host interaction for the first time.

microbiology↗

bioRxiv2018

Aedes anphevirus (AeAV): an insect-specific virus distributed worldwide in Aedes aegypti mosquitoes that has complex interplays with Wolbachia and dengue virus infection in cells

Insect specific viruses (ISVs) of the yellow fever mosquito Aedes aegypti have been demonstrated to modulate transmission of arboviruses such as dengue virus (DENV) and West Nile virus by the mosquito. The diversity and composition of the virome of Ae. aegypti, however, remains poorly understood. In this study, we characterised Aedes anphevirus (AeAV), a negative-sense RNA virus from the order Mononegavirales. AeAV identified from Aedes cell lines were infectious to both Ae. aegypti and Aedes albopictus cells, but not to three mammalian cell lines. To understand the incidence and genetic diversity of AeAV, we assembled 17 coding-complete and two partial genomes of AeAV from available RNA-Seq data. AeAV appears to transmit vertically and be present in laboratory colonies, wild-caught mosquitoes and cell lines worldwide. Phylogenetic analysis of AeAV strains indicates that as the Ae. aegypti mosquito has expanded into the Americas and Asia-Pacific, AeAV has evolved into monophyletic African, American and Asia-Pacific lineages. The endosymbiotic bacterium Wolbachia pipientis restricts positive-sense RNA viruses in Ae. aegypti. Re-analysis of a small RNA library of Ae. aegypti cells co-infected with AeAV and Wolbachia produces an abundant RNAi response consistent with persistent virus replication. We found Wolbachia enhances replication of AeAV when compared to a tetracycline cleared cell line, and AeAV modestly reduces DENV replication in vitro. The results from our study improve understanding of the diversity and evolution of the virome of Ae. aegypti and adds to previous evidence that shows Wolbachia does not restrict a range of negative strand RNA viruses.

microbiology↗