The encapsulation response is not affected in the Relish mutants. When larvae of E20 or E38 are infested with the parasitoid wasp, Leptopilina boulardi , a majority of them show an efficient encapsulation response, and very few adult wasps emerge from the infested animals. For comparison, two strains, S strain 22 and R strain 940, which have been selected for susceptibility and resistance to Leptopilina , respectively, were examined. In contrast to the Relish mutants, the S strain 22 has a much reduced response against the parasite. It should also be noted that the activation of the phenoloxidase system is normal in the Relish mutants.
IkappaB proteins have central roles in regulation of inflammation and innate immunity in mammals.
Homologs of these proteins also play an important role in regulation of the Drosophila immune response. Strong evidence is found for adaptive protein evolution in D. simulans , but not in D. melanogaster. The adaptive evolution appears to be restricted to the IkappaB domain. A history of directional selection on amino acid variation in D. simulans has been convincingly established. One potentially relevant finding is that there is strong evidence for adaptive evolution in the IkappaB domain, yet no evidence for adaptive protein evolution in the NF-kappaB domain.