Changes in Microbiome Correspond with Diminished Lung Pathophysiology Following Early-Life Respiratory Syncytial Virus Infection or Antibiotic Treatment: Microbiome Following RSV Infection.

Early-life respiratory syncytial virus (EL-RSV) infection has been implicated in long-term pulmonary disease in children. In these studies, neonatal BALB/c mice were infected at day 7 of life, leading to >35% losses in critical lung function, airway mucus metaplasia, and transcriptional hallmarks of mucus hypersecretion four weeks after RSV infection. While EL-RSV minimally reshaped the resident lung microbiota, it led to significant gut dysbiosis, including a long-term reduction of Proteobacteria that can be a source of protective metabolites related to barrier and immune function. Subsequent studies assessing whether a common infant antibiotic (ampicillin) could mitigate EL-RSV-induced lung alterations revealed further severe gut microbiome alterations and, on its own, later in life, recapitulated the full spectrum of RSV-associated alterations in lung function. Metagenomic inference showed that both RSV and ampicillin administered during early life reduced biosynthetic pathways for microbiome-derived metabolites, which are known to reinforce tight junctions, regulate inflammation, and preserve extracellular matrix elasticity. The shared loss of these metabolic programs provides a mechanistic bridge linking distinct early-life exposures to the microbiome changes and airway mechanical deficits later in life. Collectively, the data suggest that RSV and/or antibiotic-triggered gut dysbiosis is the primary insult that likely promotes improper lung maturation/repair through a metabolite-mediated mechanism and may suggest metabolite restoration as a strategy to promote proper developmental lung function.