Antigens specific to respiratory syncytial virus are produced on the surface of cells by: (1) culturing in vitro cells derived from a human or animal mucosa, (2) inoculating the cultured cells with respiratory syncytial virus, and (3) selecting virally infected cells from the culture. The resulting cells or the viral antigen(s) when partially or completely isolated from the cells have immunological and diagnostic uses in respect of infection by respiratory syncytial virus and may be used to isolate viral antibodies. A specific cell strain NM7 produced by this method from bovine nasal mucosal cells has respiratory syncytial virus antigens on its surface and its corresponding, uninfected cell strain NM5 can be infected similarly.