Respiratory syncytial virus infection alters the gut immune response to commensal bacteria

Respiratory Syncytial Virus (RSV), characterized by inflammation of the bronchioles, is a major cause of hospitalizations among infants and older adults. Early-life gut dysbiosis, an imbalance of microbiota, has been linked with elevated risk of lung infections later in life. However, our understanding of the impact of respiratory infections on the gut and its long-term consequences is limited. We hypothesize that RSV infection in mice increases gut inflammation. To test this, we intranasally infected mice with RSV, collected blood and stool samples over the course of the infection, and analyzed immune cells in the lung and colon. We saw an increase in immune cells and cytokine production in both lung and colon of infected mice. We further found an increase in antibodies binding to commensal bacteria in the intestinal lumen, which was more prominent in the colon than in the small intestines, suggesting a tissue specific difference in response to RSV. Lastly, we saw gut microbiome changes in response to RSV, such as reduced Muribaculaceae and elevated Alistipes. Together, these data suggest that respiratory infections may disrupt homeostasis beyond the lung, and respiratory virus-induced changes to the gut could influence the risk of subsequent enteric infections or chronic conditions such as inflammatory bowel disease. A better understanding of how RSV influences the gut could help to identify patients at risk for these conditions as well as potential therapeutic targets.