It’s no secret that dog ownership can provide lots of fun, happiness, and good times for both you and your dog. But even better news for pet owners – researchers have discovered that children’s risk for developing allergies and asthma is reduced when they are exposed in early infancy to a dog in the household. The scientists also identified a specific bacterial species within the gut that is critical to protecting the airways against both allergens and viral respiratory infection.\nThe study, funded by the National Institute of Allergy and Infectious Diseases (NIAID), is published in the Proceedings of the National Academy of Sciences (PNAS) and involves a multi-disciplinary group of researchers from UCSF, the University of Michigan, Henry Ford Health System and Georgia Regents University.\nThe team conducted experiments with mice and found that exposing them to dust from homes where dogs live triggered changes in the community of microbes that live in an infant's gut and reduced immune system response to common allergens.\nAmong the bacterial species in the gut microbiome of these mice, the researchers homed in on one, Lactobacillus johnsonii. When they fed it alone to mice, they found it could prevent airway inflammation due to allergens or even respiratory syncytial virus (RSV) infection. Severe RSV infection in infancy is associated with elevated asthma risk.\nThese results also suggest that changes in the gut bacteria community (gut microbiome) can affect immune function elsewhere in the body, said study co-leader Susan Lynch, an associate professor in the gastroenterology division at UCSF.\nShe said that it might be possible to use species of beneficial gut bacteria to remodel people's gut microbiomes to prevent the development of allergies or asthma, and even treat existing cases.\n"Gut microbiome manipulation represents a promising new therapeutic strategy to protect individuals against both pulmonary infection and allergic airway disease," Lynch said.