Abstract: The gut inhabits numerous microorganisms including bacteria, fungi and viruses, which maintains a relationship of dynamic equilibrium and displays a vital role in keeping healthy via coevolution with host. Previous studies about intestinal microorganisms mainly focused on the gut microbiota. In recent years, metagenomic analysis has shown that the intestine harbors various DNA viruses and RNA viruses, including eukaryotic viruses and phages. There is evidence that enteric viruses can mediate immunity through multiple ways. On the one hand, gut viruses can activate pattern recognition receptors (PRRs) to mediate the development and homeostasis of the intestinal immune system directly. On the other hand, it can regulate the composition of commensal microbiota to impact on intestinal immune homeostasis indirectly. In addition, dysbiosis of intestinal resident viruses are often associated with Crohn′s disease, Ulcerative Colitis, Colorectal Cancer and Type 2 Diabetes and its mechanism are still unclear . Thus, intestinal resident viruses play important roles in maintaining immune homeostasis and health. In this review, we summarized recently findings concerning the effect of intestinal resident viruses on immune homeostasis.

Key words: eukaryotic viruses, phages, immune homeostasis