Role of viral infections, atopy and antiviral immunity in the etiology of wheezing exacerbations among children and young adults.

BACKGROUND: At least 101 serotypes of rhinoviruses have been identified. Rhinoviruses have often been associated with trivial upper respiratory infections but more recent evidence suggests that they play a significant role in the pathogenesis of asthma exacerbations.
METHODS: The impact of rhinoviruses as a cause of respiratory morbidity in infancy and the role of rhinoviruses in causing asthma exacerbations in the children and adult population is discussed. Past and current experimental and epidemiologic evidence was assessed to suggest a causal role rather than just an association. Mechanism of susceptibility to virus infection in asthmatics were discussed, as were data indicating important interactions between allergic sensitization and rhinovirus infections in risk of asthma exacerbations.
RESULTS: Asthmatic individuals have increased severity and duration of lower airway symptoms and greater declines in lung function upon infection with rhinovirus, suggesting greater susceptibility to rhinovirus infection because of impaired antiviral immunity. Early virus-induced apoptosis, which aborts virus replication, was impaired in asthmatics. Treating allergic airway inflammation may reduce the frequency and severity of symptoms triggered by rhinoviruses.
CONCLUSIONS: The evidence in children and young adults suggests that atopy and allergic inflammation in the airways may be critical determinants of an adverse response to rhinovirus. Increased awareness of the spectrum of age groups that are affected by rhinoviruses is needed to encourage the development of new treatments and strategies that may be helpful in reducing the frequency and severity of symptoms triggered by rhinoviruses.