Differential gene expression in Drosophila melanogaster and D. nigrosparsa infected with the same Wolbachia strain

Wolbachia, maternally inherited endosymbionts, infect nearly half of all arthropod species. Wolbachia manipulate their hosts to maximize their transmission, but they can also provide benefits such as nutrients and resistance to viruses for their hosts. The Wolbachia strain wMel was recently found to increase locomotor activities and possibly trigger cytoplasmic incompatibility in the fly Drosophila nigrosparsa. Here, we compared differential gene expression in Drosophila melanogaster (original host) and D. nigrosparsa (novel host), both uninfected and infected with wMel, using RNA sequencing to see if the two Drosophila species respond to the infection in the same or different ways. A total of 2164 orthologous genes were used. We found species-specific gene expression patterns. Significant changes shared by the fly species were confined to the expression of genes involved in heme binding and oxidation-reduction; the two host species differently changed the expression of genes when infected. Some of the genes were down-regulated in the infected D. nigrosparsa, which might indicate small positive effects of Wolbachia. We discuss our findings also in the light of how Wolbachia survive within both the native and the novel host.