The intestinal mucosal surface in all vertebrates is exposed to enormous numbers of
microorganisms that include bacteria, archaea, fungi and viruses. Coexistence of the host
with the gut microbiota represents an active and mutually beneficial relationship that helps to
shape the mucosal and systemic immune systems of both mammals and teleosts (ray-finned
fish). Due to the potential for enteric microorganisms to invade intestinal tissue and induce
local and/or systemic inflammation, the mucosal immune system has developed a number of …