Bacteriophage WO Can Mediate Horizontal Gene Transfer in Endosymbiotic Wolbachia Genomes

Phage- mediated horizontal gene transfer(HGT) is common in free-living bacteria, and many transferred genescan play a significant role in their new bacterial hosts. However, there are few reports concerning phage- mediatedHGT in endosymbionts (obligate intracellular bacteria within animal or plant hosts), such as Wolbachia. The Wolbachia-infecting temperate phage WO can actively shift among Wolbachiagenomes and has the potential to mediateHGT between Wolbachiastrains. In the present study, we extend previous findings by validating that the phage WO can mediatetransfer of non-phage genes. To do so, we utilized bioinformatic, phylogenetic, and molecular analyses based on all sequenced Wolbachiaand phage WO genomes. Our results show that the phage WO can mediateHGT between Wolbachiastrains, regardless of whether the transferred genesoriginate from Wolbachiaor other unrelated bacteria.