Ricerc@Sapienza

Acute bronchiolitis, the most common lower respiratory tract infection and the leading cause of hospitalization in infants less than 12 months of age. It is caused by respiratory viruses, in particular Respiratory Syncytial Virus (RSV), Rhinovirus (RV) and Metapneumovirus (MPV) are frequently involved. It is still unknown why some full-term previously healthy infants may present a severe form of bronchiolitis, but the active interaction among host and viral factors is pivotal to determining the severity of respiratory symptoms. Many viral factors (virus type, subtype and genotype and viral load) may be implicated in bronchiolitis pathogenesis. Bronchiolitis can be viewed as a disease of defective (enhanced or depressed) immunoregulation. Th1 polarization is correlated with the efficient eradication of viral infection, whereas Th2 leads to an inefficient viral elimination and to a more severe disease. We propose a large study on infants hospitalized for bronchiolitis with the aim of: (i) characterizing the clinical phenotypes of bronchiolitis; (ii) establishing association of viral factors with patients' clinical features and disease severity; (iii) giving insights into the immunopathogenesis of viral bronchiolitis. The ultimate goal is the identification of severe bronchiolitis determinants with the aim of improving early diagnosis and developing targeted therapies.