The small hydrophobic protein of human respiratory syncytial virus: comparison between antigenic subgroups A and B

The nucleotide and amino acid sequences of the mRNA and predicted polypeptide of the integral membrane small hydrophobic (SH) protein of human respiratory syncytial virus strain 18537 (a prototype strain of antigenic subgroup B) were determined from cloned cDNA. At the nucleotide and amino acid levels there was 78% and 76% identity, respectively, with the previously described SH mRNA and protein of strain A2 (a prototype strain of subgroup A). Most of the amino acid substitutions occurred in the predicted ectodomain (50% identity). The pattern of posttranslational processing of the strain 18537 SH protein was very similar to that of strain A2, yielding a nonglycosylated form and two glycosylated forms. Analysis of released virions of strain A2 by immunoprecipitation with SH-specific antibodies suggested that the major non-glycosylated species and one of the glycosylated species are virion structural components.