Conservation of the respiratory syncytial virus SH gene

Respiratory syncytial virus (RSV) encodes a short (64 or 65 amino acids) hydrophobic (SH) protein whose function in viral replication and pathogenesis is not understood. We carried out molecular epidemiological studies of the SH gene during the 1998-1999 seasonal epidemic in New Haven, Connecticut. Strains circulating during the epidemic were related to viruses identified worldwide. The SH gene transcriptional control signals were conserved in 70 (98.6%) of 71 isolates that we sequenced. The deduced amino acid sequence of the SH protein was nearly identical to subgroup A and subgroup B reference strains that were isolated in 1961 and 1962, respectively. Twenty-six (96.3%) of 27 subgroup A strains contained 0 or 1 amino acid substitution, compared with that of the reference A2 strain. Most subgroup B isolates (38 [86.4%] of 44 strains) contained 0, 1, or 2 amino acid substitutions, compared with that of the reference B18537 strain.