Illumina Sequencing of different Wolbachia strains wPip infecting the Culex pipiens mosquitoes complex. Wolbachia endosymbiont of Culex pipiens strain:wPip

Maternally inherited Wolbachia are commonly found in arthropods and known to manipulate host reproduction to enhance their vertical spread in the host population. The most common strategy used by Wolbachia is called cytoplasmic incompatibility (CI) which cause a drastic reduction in the hatching rate of eggs. CI occurs when infected male mates with uninfected female or female infected with incompatible Wolbachia strains. In the Culex pipiens mosquitoes complex all the individuals are infected with Wolbachia wPip strain. Multi Locus Sequence Typing usually used to classify Wolbachia strains revealed no genetic diversity within wPip strain harbouring different CI patterns. To genetically differentiate these strains hyper variables markers such as repetitive element were needed. These markers revealed that wPip in a monophyletic group divided in five group : wPip_I to wPip_V. This highlight the genetic proximity of all wPip strains.Many crossing experiment between mosquitoes infected with Wolbachia from these five groups have revealed the highest diversity of CI patterns observed among all the arthropods in which Wolbachia induced CI. Even if CI was discovered decades ago, little is known about its genetic basis. Culex pipiens infected by Wolbachia genetically very close but habouring different CI patterns offers a perfect system for a comparative genomic study to find the genetic basis of CI. We thus sequenced Wolbachia strains harbouring different CI patterns to find variable genes between these strains.