Respiratory syncytial virus-Host interaction in the pathogenesis of bronchiolitis and its impact on respiratory morbidity in later life.

Respiratory syncytial virus (RSV) is the most common agent of severe airway disease in infants and young children. Large epidemiologic studies have demonstrated a clear relationship between RSV infection and subsequent recurrent wheezing and asthma into childhood, thought to be predominantly related to long-term changes in neuroimmune control of airway tone rather than to allergic sensitization. These changes appear to be governed by the severity of the first RSV infection in infancy which in term depends on viral characteristics and load, but perhaps as importantly, on the genetic susceptibility and on the constitutional characteristic of the host. A variety of viral and host factors and their interplay modify the efficiency of the response to infection, including viral replication and the magnitude of structural and functional damage to the respiratory structures, and ultimately the extent, severity, and duration of subsequent wheezing.