Differential Regulation of Immune Signaling and Survival Response in Drosophila melanogaster Larvae upon Steinernema carpocapsae Nematode Infection.

is an excellent model to dissect the molecular components and pathways of the innate anti-pathogen immune response. The nematode parasite and its mutualistic bacterium form a complex that is highly pathogenic to insects, including . We have used symbiotic (carrying ) and axenic (lacking ) nematodes to probe the regulation of genes belonging to different immune signaling pathways in larvae and assess the survival response of certain mutants to these pathogens. We found that both types of upregulate (Toll), but not (Imd); whereas axenic strongly upregulate (Jnk), (Jak/Stat), (TGFβ, Activin), and (TGFβ, BMP). We further found that inactivation of and confers a survival advantage to larvae infected with axenic , whereas mutating promotes the survival of larvae infected with symbiotic nematodes.