Establishing Drosophila melanogaster as a model for mechanistic study of immune priming

Unlike vertebrates, invertebrates lack a lymphocyte-based adaptive immune system. There is no known mechanism by which the invertebrate innate immune system can acquire immunological memory against a pathogen. Yet, numerous studies have shown that when invertebrate organisms are exposed to a pathogen, they can acquire immunity against that pathogen such that they are able to mount an enhanced, and often very specific and/or long-lasting, immune response upon subsequent exposure. This phenomenon, known as “immune priming”, has been observed in a wide diversity of invertebrate organisms against numerous types of pathogens. The immunological community is encumbered by conflicting evidence surrounding immune priming. Despite efforts to understand how invertebrates acquire immunity, no single mechanism has been directly confirmed, and suggested mechanisms may not be translatable between species. Drosophila melanogaster is a well-established model organism that offers a multitude of readily available genetic tools and methods for studying innate immunity. This work utilizes D. melanogaster to investigate immune priming, as well as the specificity of acquired protection against systemic bacterial infections over time. This work contributes to scientific understanding about the mechanistic basis of immune priming. In the future, we might leverage these mechanisms to our advantage by artificially boosting immune defenses of organisms beneficial to human society, such as livestock, crop plants, and pollinators.