Interactions of the bacteriome, virome, and immune system in the nose.

Emerging evidence suggests that the nasal microbiome may influence host susceptibility to initial development and severity of respiratory viral infections. While not as extensively studied as the microbiota of the alimentary tract, it is now clearly established that the microbial composition of this niche is influenced by medical, social and pharmacological influences, predisposing some sub-populations to respiratory infections. The resulting specific microbial profiles may explain variance in susceptibility to viral infection. This review summaries the evolution and constituents of the commensal nasal microbiome; the bacterial-virus, bacterial-host and interbacterial interactions which potentiate disease; and considers the effects of interventions such as vaccination and probiotics.