Drosophila Immunity

Ever wonder how your body prevents your cuts from getting infected or how it fights off that cold virus? Well, the answer, at least in part, is the innate immune system. Your innate immune system is responsible for detecting intruders and fighting them off, regardless of what kind of intruder it is. One of the things that differentiates us from insects is that we have another layer of immunity called adaptive immunity, which remembers previous intruders and caters a response that is specific to each one. Because insects lack adaptive immunity, a layer of complication is removed and it is much easier to study their immunity. Luckily for us, innate immunity in insects such as Drosophila and innate immunity in humans is almost identical, which is why we can use Drosophila as a model organism.

Drosophila immunity conisists of two protein cascade pathways, which both culminate in the expression of antimicrobial peptides. One of the pathways, called the Imd pathway, is reponsible for fighting off gram negative bacterial infection. The other pathway, the Toll pathway, is responsible for fighting off gram positve bacteria and fungi. Below is an image of the Drosophila immune pathways taken from the Deveal et al paper I have linked in my first post. The diagram beautifully illustrates the complexity and elegance of the immune pathways. To this point, even though much of the pathways has been deduced, their complete functions remain to be seen. This field is just coming into its own.