Infection with respiratory syncytial virus alters peptidergic innervation in the lower airways of guinea-pigs

To probe the mechanisms by which respiratory syncytial virus (RSV) infection in early life forms an important risk factor for the development of chronic asthma, an airway hyper-responsiveness (AHR) animal model of guinea-pigs with persistent RSV infection was established by intranasal instillation of 2 x 10(5) plaque-forming units RSV. On days 0, 7, 28, 42 and 60 postinoculation, the RSV copy numbers, airway function and peptidergic innervation were measured in the peripheral airways. The results showed that the virus was persistent in the lungs. During persistent infection (days 42 and 60), the lung resistance and the total cells, neutrophils and eosinophils of infected guinea-pigs increased significantly; the airway showed signs of chronic inflammation; and the substance P- and calcitonin gene-related peptide-positive fibres increased, but vasoactive intestinal polypeptide-positive fibres decreased. These results suggest that persistent RSV infection can cause long-term chronic airway inflammation and persistent airway neural network abnormality, which may be related to the occurrence of AHR.