Respiratory syncytial (RS) virus is a major cause of lower respiratory tract infections among infants and children in both developing and developed countries. No vaccine is available for the prevention of these infections and therapeutic options are limited. Reinfections with RS virus are the norm and occur throughout life. We are investigating antigenic and genetic diversity among RS viruses to assess the extent to which such diversity may influence vaccine efficacy. The molecular epidemiology of RS viruses is being studied in developing and developed countries and among normal and immunocompromised host populations. Immune escape variants of RS virus are being selected in the laboratory and characterized so as to define the capacity of the virus to evade immune responses.
