ANTIGENIC HETEROGENEITY OF THE ATTACHMENT PROTEIN OF BOVINE RESPIRATORY SYNCYTIAL VIRUS

A panel of 23 monoclonal antibodies (MAbs) specific for the attachment (G) glycoprotein of bovine respiratory syncytial virus (BRS virus), recognizing seven antigenic areas on the G protein, was used to determine the antigenic heterogeneity among 19 BRS viruses isolated over a 20 year period from various parts of the world. The pattern of reactivity of the isolates, as determined by ELISA, identified two major subgroups of BRSV. This finding was confirmed by radioimmunoprecipitation of the G protein by the MAbs and was also demonstrated using polyclonal sera obtained from calves hyperimmunized with BRS virus strains from each subgroup. The subgroups could also be differentiated by differences in the apparent M(r) of the fusion (F) glycoprotein and its cleavage products. The apparent M(r)s of the F-0, F-1 and F-2 polypeptides were 73K, 46K and 17K for subgroup A strains and 77K, 46K and 23K for subgroup B strains. These studies provide evidence for two major lineages of BRS virus, similar to the situation with human RS virus.