Viruses are part of a healthy microbiome

Traditionally, we seem to only think of “good bacteria” when considering the elements of a healthy microbiome. However, recent research provides evidence that viruses are also important for promoting gut health. Asymptomatic viruses that infect intraepithelial cells in the GI tract can initiate an immune response. The concept is similar to the live adenovirus vaccine that we discussed in class. Until recently, there has only been some evidence of viruses positive role in immune activation: For example, research on mice showed that a murine norovirus infection induced interferon release that stimulated immune cell development and even tissue regeneration. In a recently published paper, researchers treated wild-type mice with an antiviral for an extended period of time (6 weeks), and it specifically reduced the quantity of intraepithelial leukocytes (IELs). Next, by knocking out the RIG-I receptor - an important sensor of dsRNA - the authors were able to determine that commensal viruses contribute to immune defense through the RIG-I pathway. This research adds to our current conception of the microbiome and the positive synergistic relationship between our gut and our microscopic friends. 

~Avi Kaye

https://www.nature.com/articles/s41590-019-0530-y