Symbiosis Comes of Age at the 10th Biennial Meeting of Wolbachia Researchers

Wolbachia pipientis is an alphaproteobacterial obligate intracellular microbe and arguably the most successful infection on our planet, colonizing 40% to 60% of insect species. Wolbachia spp. are also present in most, but not all, filarial nematodes, where they are obligate mutualists and are the targets for antifilarial drug discovery. Although Wolbachia spp. are related to important human pathogens, they do not infect mammals but instead are well known for their reproductive manipulations of insect populations, inducing the following phenotypes: male killing, feminization, parthenogenesis induction, and cytoplasmic incompatibility (CI). The most common of these, CI, results in a sperm-egg incompatibility and increases the relative fecundity of infected females in a population. In the last decade, Wolbachia spp. have also been shown to provide a benefit to insects, where the infection can inhibit RNA virus replication within the host. Wolbachia spp. cannot be cultivated outside host cells, and no genetic tools are available in the symbiont, limiting approaches available for their study. This means that many questions fundamental to our understanding of Wolbachia basic biology remained unknown for decades. The 10th biennial international Wolbachia conference, Wolbachia Evolution, Ecology, Genomics and Cell Biology: A Chronicle of the Most Ubiquitous Symbiont, was held on 17 to 22 June 2018 in Salem, MA. In this review, we highlight the new science presented at the meeting, link it to prior efforts to answer these questions across the Wolbachia genus, and present the importance of these findings to the field of symbiosis. The topics covered in this review are based on the presentations at the conference.