Objective To study the concentration of neurotrophins( including NGF, BDNF, NT3 and NT4) in the lung of SD rats infected by respiratory syncytial virus( RSV) , and to explore the relationship between the concentration of the neurotrophins, airway hyperresponsiveness and airway neural plasticity.Methods Twenty SD newborn rats were randomly divided into a control group and a RSV-infected group with ten rats in each group. The RSV-infected group were infected with 5 ×104 TCID50/0. 1 mL RSV each week. After 8 weeks, the bronchial responsiveness of the SD rats was assessed. The bronchial inflammation was assessed by HE staining with left lung. Synaptophysin and neurofilament expressions in the lung of SD rats were assayed by the immunohistochemistry staining. In situ hybridization was used to detect the RSV RNA in the lung. The concentration of neurotrophins in the lung of SD rats were detected by ELISA. Results The RSV-infected group showed elevated airway hyperresponsiveness and more inflammatory cells infiltrated in the lung; In situ hybridization showed positive signal of RSV RNA in lung interstitium of the RSV-infected rats. Synaptophysin and neurofilame levels in the airway were increased in the RSV-infected group. Supernatant levels of NGF and BDNF were significantly increased compared with the control group ( P lt;0. 05) . The NT3 and NT4 levels had no significant difference in all groups. The expressions of NGF and BDNF were positively related to the expressions of synaptophysin( r1 = 0. 892, r2 = 0. 995, P lt; 0. 05) and neurofilament( r1 = 0. 949, r2 =0. 936, P lt;0. 05) , also positively related to the airway hyperresponsiveness ( r1 =0. 929, r2 = 0. 910, P lt; 0. 05) . Conclusion RSV infection results in increased expressions of NGF and BDNF in the lung, which are correlated to the change of airway neural plasticity and airway hyperresponsiveness.