Transgenic expression of cif genes from Wolbachia strain wAlbB recapitulates cytoplasmic incompatibility in Aedes aegypti.

Abstract

The endosymbiotic bacteria Wolbachia can invade insect populations by modifying host reproduction through cytoplasmic incompatibility (CI), an effect that results in embryonic lethality when Wolbachia-carrying males mate with Wolbachia-free females. Here we describe a transgenic system for recreating CI in the major arbovirus vector Aedes aegypti using CI factor (cif) genes from wAlbB, a Wolbachia strain currently being deployed to reduce dengue transmission. CI-like sterility was induced when cifA and cifB were co-expressed in testes; this sterility could be rescued by maternal cifA expression, thereby reproducing the pattern of Wolbachia-induced CI. Expression of cifB alone was associated with extensive DNA damage and disrupted spermatogenesis. The strength of rescue by maternal cifA expression was dependent on the comparative levels of cifA/cifB expression in males. These findings are consistent with CifB acting as a toxin and CifA as an antitoxin, with CifA attenuating CifB toxicity in both the male germline and in developing embryos.