Natural Polymorphisms and Resistance-Associated Mutations in the Fusion Protein of Respiratory Syncytial Virus (RSV): Effects on RSV Susceptibility to Palivizumab

Specific mutations in respiratory syncytial virus (RSV) fusion protein can cause palivizumab resistance. We assessed the incidence of sequence polymorphisms andpalivizumab resistance in clinical RSV isolates collected from immunoprophylaxisnaive subjects. Polymorphismswere identified at low frequency, and only polymorphicmutations in antigenic site A (,1%of all polymorphisms) conferred palivizumab resistance.