A virus that controls reproduction

The obligate intracellular bacteria Wolbachia (pictured), which infects 40% of arthropods, can manipulate its host to ensure its maintenance in the population. An example is cytoplasmic incompatibility, which occurs when infected males mate with uninfected females, and causes embryonic lethality (mating with an infected female produces viable offspring). Two Wolbachia genes responsible for this phenotype have been identified, and they are viral (link to paper). A comparison of genome sequences of different Wolbachia strains that do or do not cause cytoplasmic incompatibility (CI) revealed two genes that were candidates for this phenotype. Both genes are transcribed in the testes of fruit flies, but at lower levels in older male flies which show decreased CI. When either gene was expressed in male transgenic fruit flies, there was no effect on hatch rates after mating with uninfected females. When both genes were expressed in male flies, mating with uninfected females led to substantially reduced hatch rates. This transgene-induced lethality was rescued when the flies were mated with Wolbachia-infected females. The two genes that together cause CI are called cytoplasmic incompatibility factor A and B (cifA, cifB). The cytological defects caused by these genes resemble those observed in Wolbachia-induced CI: most embryos do not divide more than two or three times. Remarkably (or perhaps not!), cifA and cifB are not Wolbachia genes, but are viral. Wolbachia are infected wi...
Source: virology blog - Category: Virology Authors: Tags: Basic virology Information arthropod bacteriophage cytoplasmic incompatibility lysogen prophage viral virus WO wolbachia Source Type: blogs