The Drosophila immunity handbook

Animals possess efficient mechanisms for detecting and neutralizing infection. The application of Drosophila genetics to the study of these mechanisms has generated insights into insect immunity and uncovered general principles of animal host defense. These studies have shown that Drosophila has multiple defense “modules” that can be deployed in a coordinated response against distinct pathogens. These include physical barriers such as epithelia and chitin, production of reactive oxygen species, antimicrobial factors, blood clotting, the melanization reaction, and complex cellular responses. These responses are accompanied by metabolic reprogramming to fuel the immune system and effectively combat pathogens. Recent studies have highlighted additional mechanisms that contribute to host defense, such as symbiont mediated immunity, disease tolerance mechanisms, and behavioral immunity. These studies reveal broader roles of the immune system beyond infection, notably in disease pathologies such as neurodegeneration or cancer. This remarkable animal model has given us a better understanding of the multiple roles of the immune system at the organismal level. Although it is difficult to summarize the sheer number of studies published in Drosophila immunity in recent years, here we aim to provide an overview of recent research trends, challenges, and discoveries in immunity through the lens of Drosophila. We hope that this overview will introduce scientists to the sophisticated fly immune system, draw interest to exciting recent findings in the field, and push new horizons of research by contextualizing existing research and highlighting exciting avenues to explore.