In this paper the authors assessed whether the level of innate immune priming induced by different Wolbachia strains in Aedes aegypti is correlated with the degree of protection conferred against bacterial pathogens. They showed that Wolbachia strains wMel and wMelPop‚ currently being tested for field release for dengue biocontrol‚ differ in their protective abilities. The wMelPop strain provides stronger‚ more broad-based protection than wMel‚ and this is likely explained by both the higher induction of immune gene expression and the strain-specific activation of particular genes.