The human respiratory syncytial virus (RSV) is often associated with airway obstruction and is suspected to induce bronchial hyperreactivity. Interactions of viral proteins with cellular components may be responsible for epithelial damage leading to bronchial hyperreactivity. In this study, we describe the localization of the 14.7-kD nonstructural protein 2 (NS2) in RSV-infected cells. The detection of NS2 was performed using antipeptide antibodies elicited against amino acids 109-123 of the predicted sequence of the NS2 protein. By using recombinant NS2, we could clearly demonstrate the specificity of the antipeptide antibodies. With this defined tool, NS2 could be first detected in infected HEp-2 cells at 10 h p.i. subsequently to the detection of N protein. In double-staining experiments, colocalization of NS2, P protein and N protein was demonstrated. The antipeptide antibodies recognized the NS2 protein in the sediment of RSV-infected HEp-2 cells lysed with RIPA buffer at 48 h p.i. The results agree with the reported interaction of RSV with cytoskeletal intermediate filaments. These interactions may implicate essential cellular functions suspected to induce bronchial hyperreactivity.