Effect of Faecalibacterium duncaniae on the composition of the gut microbiota during influenza infection

Influenza still poses serious medical and economic issues worldwide, and preventive strategies that limit infection incidence and disease severity would be invaluable. A growing body of literature data suggests that manipulation of the gut microbiota can usefully influence influenza outcomes. Indeed, host immune responses to respiratory viruses are closely linked to the microbiome and metabolism via the gut-lung axis. Faecalibacterium duncaniae is a canonical, butyrate-producing species endowed with anti-inflammatory properties and has been used clinically in the treatment of gut diseases. In view of butyrate functions in influenza, we hypothesized that F. duncaniae can prophylactically protect against this disease in a mouse model. In the present study, we demonstrate that F. duncaniae partially protects against influenza by limiting weight loss, viral load and lung/gut inflammation. The protective effects were associated with a distinct shift in gut microbial composition in F. duncaniae-treated IAV-infected mice compared to vehicle-treated IAV-infected mice and with the recovery in short chain fatty acid levels (which fall markedly during infection).