Effect of Wolbachia wAlbB on a positive-sense RNA negev-like virus: a novel virus persistently infecting Aedes albopictus mosquitoes and cells

The Aedes aegypti mosquito is the primary vector of several medically important arboviruses. The endosymbiotic bacterium, Wolbachia pipientis, has emerged as a means of blocking transmission of arboviruses such as dengue and Zika viruses. One Wolbachia strain that has shown potential in field trials is wAlbB, a naturally occurring Wolbachia strain of the Asian tiger mosquito Aedes albopictus. When transinfected into Ae. aegypti, wAlbB exhibits strong virus inhibition. In addition to modulating arboviruses, Wolbachia also modulates some insect-specific viruses. Here, we explored the effect of Wolbachia on the virome of the Ae. albopictus cell line Aa23 naturally infected with wAlbB and also a stably transinfected recipient Ae. aegypti cell line (Aag2.wAlbB). RNA sequencing and bioinformatic analysis on both cell lines revealed an 11 kb genome of a single-stranded positive-sense RNA negev-like virus related to the recently proposed negevirus taxon. We denoted this novel virus as Aedes albopictus negev-like virus (AalNLV). Tetracycline clearance of Wolbachia from Aa23 cells did not significantly affect AalNLV levels, while in Aag2.wAlbB cells, a significant increase in virus genome RNA copies was observed. We further investigated the inhibitory effect of wAlbB on AalNLV and another positive-sense RNA virus, cell fusing agent virus, which is present in Aag2 cells and known to be suppressed by Wolbachia. wAlbB suppressed both viruses, with the effect on AalNLV being more striking. The findings from this study further supplement our understanding of the complex interaction between Wolbachia, host and virome.