Authors

Discussion

Wolbachia, an intracellular alpha-proteobacterium, is the most prevalent symbiont of animals on the planet, infecting more than half of terrestrial arthropods and a small proportion of parasitic nematodes. Notably, it is very common in arthropods of medical and veterinary importance, including biting Diptera, lice, bedbugs, fleas and mites, as well as approximately half of filarial nematode species. Wolbachia can induce detrimental reproductive phenotypes, such as cytoplasmic incompatibility and male killing, whereas in a minority of hosts it appears to be mutualistic. Its remarkable ability to block pathogen transmission in transinfected insect vectors has stimulated an explosion of basic and applied research on Wolbachia, especially the parasitic strains of the A and B clades, but the wider diversity of this highly plastic symbiont remains neglected. Here, I explore the genomic features of some newly characterised clades from filarial nematodes, fleas and bedbugs and reveal how they threaten to raise more questions than answers. I also consider how technical advances are allowing transcriptional regulation in Wolbachia to be explored in unprecedented detail and depth, and present new findings on the dynamic transcriptome of two Wolbachia strains in use for vector-borne disease control as they are exposed to stressors in vitro. Finally, our culture and genome sequencing of a putatively mutualistic Wolbachia from cat fleas provides exciting opportunities to dissect the regulation of vitamin biosynthesis under a variety of conditions.