- A recessive mutation, immune deficiency (imd), defines two distinct control pathways in the Drosophila host defense. Lemaitre, B., Kromer-Metzger, E., Michaut, L., Nicolas, E., Meister, M., Georgel, P., Reichhart, J.M., Hoffmann, J.A. Proc. Natl. Acad. Sci. U.S.A. (1995)