Drosophila immunity: paths and patterns

Flies respond to infection with both humoral and cellular immune defenses, including a powerful set of inducible peptide antibiotics as well as actively proliferating and differentiating blood cells. The system that activates these responses is related to that of the innate immune defense in humans. A key role in Drosophila immunity is played by the recently discovered peptidoglycan recognition proteins. These pattern recognition molecules relay signals via two main signaling pathways. The imd/Relish pathway is responsible for the main part of the humoral response. The Toll/Dif pathway activates the blood cells and induces the antifungal peptide Drosomycin.