Primary respiratory syncytial virus infection: pathology, immune response, and evaluation of vaccine challenge strains in a new mouse model.

Respiratory syncytial virus (RSV) is the primary cause of lower respiratory tract illness in young children. Vaccine development has been hampered by the experience of the formalin-inactivated vaccine tested in the 1960's. Currently, several vaccine candidates are under development and immune response to these candidate vaccines must be evaluated closely. We introduce a novel low-dose murine model of RSV infection and a new pathologic scoring system for the resultant pulmonary disease. We have also developed new sensitive methods for measuring cytokine expression. We then used this new model to test vaccine challenge strains of RSV in order to determine their pathogenicity.