Immunological differences between the envelope glycoproteins of two strains of human respiratory syncytial virus.

The envelope glycoproteins of two distinct strains of respiratory syncytial virus (RSV) (Long and 18537 strains) were purified by affinity chromatography and characterized by immunological methods. The fusion (F) proteins from the two strains were similar in molecular weight by gel electrophoresis and were very closely related immunologically. Rabbit antisera to either F protein reacted with near equivalent titres with the heterologous F protein by Western blot, enzyme-linked immunoassay (EIA), neutralization and fusion inhibition assays. In contrast to the similarity of the F proteins, the attachment proteins (G) differed significantly. The 18537 G protein had a molecular weight of 78K compared to 84K for the Long G protein. Rabbit antisera to the G proteins clearly reacted preferentially with the homologous protein, although some cross-reactivity was noted by Western blot and EIA. Anti-G serum neutralized the homologous strain of RSV in the presence or absence of complement to much higher titre than the heterologous virus strain. The implications for vaccine development are discussed.