About the Authors: Xi Liu Affiliation: Cornell Institute for Host Microbe Interactions and Disease, Department of Entomology, Cornell University, Ithaca, New York, United States of America Jeffrey J. Hodgson Affiliations Cornell Institute for Host Microbe Interactions and Disease, Department of Entomology, Cornell University, Ithaca, New York, United States of America, Boyce Thompson Institute, Cornell University, Ithaca, New York, United States of America Nicolas Buchon * E-mail: nicolas.buchon@cornell.edu Affiliation: Cornell Institute for Host Microbe Interactions and Disease, Department of Entomology, Cornell University, Ithaca, New York, United States of America ORCID http://orcid.org/0000-0003-3636-8387Citation: Liu X, Hodgson JJ, Buchon N (2017) Drosophila as a model for homeostatic, antibacterial, and antiviral mechanisms in the gut. The fly GI tract is composed of self-renewing digestive and absorptive tissues and shares several properties with the mammalian counterparts, the stomach, small intestine, and colon. ...in mammals, ISCs self-renew and differentiate into intermediate cell types the transit amplifying cells, which proliferate and further differentiate into ECs or secretory cells (EEs, Goblet cells, and Tuft cells), and dedicated Paneth cell progenitors that mature into Paneth cells (Fig 1B). (B) Similarly, the mammalian intestinal epithelium is composed of progenitor and Paneth cells residing at the base of crypts and absorptive cells (ECs) and secretory cells (EE and Goblet cells) that progress towards the apex of the villus. Germ-free and derivative gnotobiotic flies (i.e., reassociated with one or more bacteria) provide a less complex approach for in-depth analyses of the impact individual microbes have on gut and/or whole fly homeostasis. Gut microbes...