The Fusion Glycoproteins of Human Respiratory Syncytial Virus of Subgroups A and B: Sequence Conservation Provides a Structural Basis for Antigenic Relatedness

Two major antigenic subgroups (A and B) have been described for human respiratory syncytial virus. The complete nucleotide sequence was determined for the fusion (F) mRNA of the subgroup B strain 18537 and the amino acid sequence of the F protein deduced, for comparison with the previously described sequences for the A2 strain of subgroup A. The F proteins (excluding the cleaved signal peptide) were 91% identical between the subgroups, consistent with the previously described high degree of antigenic relatedness. The greatest divergence occurred within the F2 subunit immediately preceding the cleavage activation site.