Microbiology: a backup for bacteria.

Abstract

The finding that intestinal viruses can substitute for intestinal bacteria to promote the health of their mammalian hosts raises the possibility that viruses in the gut may be beneficial in some circumstances. See Letter p.94 It is widely accepted that commensal bacteria in the human intestine have important physiological and health effects. This paper focuses on the much less studied relationship between eukaryotic viruses and mammalian hosts, and suggests that viral members of the gut microbiota can enter symbiotic relationships providing a beneficial effect similar to that provided by the bacteria colonizing our intestines. Ken Cadwell et al. demonstrate that persistent infection of mice with various strains of enteric murine norovirus (MNV) can reverse abnormalities in intestinal morphology and lymphoid cells. Additionally, MNV infection overcomes the deleterious effects of antibiotic treatment in models of infectious or chemical intestinal injury.