Beyond the gut bacterial microbiota: The gut virome

Columpsi, Paola; Sacchi, Paolo; Zuccaro, Valentina; Cima, Serena; Sarda, Cristina; Mariani, Marcello; Gori, Andrea; Bruno, Raffaele

The gastrointestinal tract is colonized with a highly different population of bacterial, viral, ad fungal species; viruses are reported to be dominant. The composition of gut virome is closely related to dietary habits and surrounding environment. Host and their intestinal microbes live in a dynamic equilibrium and viruses stimulate a low degree of immune responses without causing symptoms (host tolerance). However, intestinal phages could lead to a rupture of eubiosis and may contribute to the shift from health to disease in humans and animals. Viral nucleic acids and other products of lysis of bacteria serve as pathogen‐associated molecular patterns (PAMPs) and could trigger specific inflammatory modulations. At the same time, phages could elicit innate antiviral immune responses. Toll‐like receptors (TLRs) operated as innate antiviral immune sensors and their activation triggers signaling cascades that lead to inflammatory response. J. Med. Virol. 88:1467–1472, 2016. © 2016 Wiley Periodicals, Inc.