RNase HI contributes to virus blocking in the mosquito .

The endosymbiotic bacterium blocks replication of several arboviruses in transinfected mosquitoes. However, the mechanism of virus blocking remains poorly understood. Here, we characterized an gene from , which is rapidly induced in response to dengue virus (DENV) infection. Knocking down using antisense RNA in -transinfected mosquito cell lines and mosquitoes led to increased DENV replication. Furthermore, overexpression of RNase HI, in the absence of , led to reduced replication of a positive sense RNA virus, but had no effect on a negative sense RNA virus, a familiar scenario in -infected cells. Altogether, our results provide compelling evidence for the missing link between early -mediated virus blocking and degradation of viral RNA. These findings and the successful pioneered knockdown of genes using antisense RNA in cell line and mosquitoes enable new ways to manipulate and study the complex endosymbiont-host interactions.