The recombinant human RSV (strain RSS-2) consists of 519 amino acids and predicts a molecular mass of 57.8 kDa. The RSV F0 precursor protein is cleaved into the disulfide-linked F1 and F2 subunits. As a result of glycosylation, the apparent molecular mass of the F0 and F1 is approximately 79.6 kDa and 63.4 KDa in SDS-PAGE under non-reducing conditions, respectively.