Wolbachia suppresses cell fusing agent virus in mosquito cells

The genus Flavivirus contains a large number of positive-sense ssRNA viruses. While some are transmitted by mosquitoes or other arthropods and are pathogenic to humans and animals (e. g. dengue and Zika viruses), some are insect-specific and do not replicate in vertebrate cells. These are known as insect-specific flaviviruses (ISFs). Cell fusing agent virus (CFAV) was the first described ISF, which was detected in an Aedes aegypti cell line, Aag2. Here, we investigated the effect of Wolbachia, a widespread endosymbiont of many insect species, that is known to block replication of several pathogenic flaviviruses, on CFAV. Our results demonstrated that, in mosquito cells, Wolbachia vastly suppresses replication of CFAV, with significantly less CFAV viral interfering small RNAs produced in the cells. However, removal of Wolbachia with tetracycline led to increased CFAV replication. These results suggest that Wolbachia is also able to suppress an ISF.