Wolbachia manipulates insect spermatozoa with a nuclear toxin

Publication of the LBMC in the journal Current biology on February 7, 2022. CNRS-INSB communication on February 21, 2022. Wolbachia are widespread endosymbiotic bacteria that manipulate the reproduction of arthropods through a diversity of cellular mechanisms. In cytoplasmic incompatibility (CI), a sterility syndrome originally discovered in the mosquito Culex pipiens , uninfected eggs fertilized by sperm from infected males are selectively killed during embryo development following the abortive segregation of paternal chromosomes in the zygote. Despite the recent discovery of Wolbachia CI factor (cif) genes, the mechanism by which they control the fate of paternal chromosomes at fertilization remains unknown. Here, we have analyzed the cytological distribution and cellular impact of CidA and CidB, a pair of Cif proteins from the Culex -infecting Wolbachia strain w Pip. We show that expression of CidB in Drosophila S2R+ cells induces apoptosis unless CidA is co-expressed and associated with its partner.