Density dependent enhancement effect ofWolbachiaand the host RNAi response to a densovirus inAedescells

The endosymbiotic bacteriumWolbachia pipientishas been shown to restrict a range of RNA viruses inDrosophila melanogasterand transinfected dengue mosquito,Aedes aegypti. Here, we show thatWolbachiainfection enhances replication of Aedes albopictus densovirus (AalDNV-1), a single stranded DNA virus, inAedescell lines in a density-dependent manner. Analysis of previously produced small RNAs of Aag2 cells showed thatWolbachia-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 U1bias 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 byWolbachia. Further, we report the generation of vpiRNAs in a DNA virus-host interaction for the first time.